TRT and GLP-1 Medicines: The Definitive Guide

What is TRT with a GLP-1 medicine?

TRT with a GLP-1 medicine means taking prescribed testosterone and a GLP-1 weight or diabetes medicine at the same time. The two do different jobs. Testosterone replaces a hormone your body is not making enough of. A GLP-1 receptor agonist acts like GLP-1, a hormone the gut releases after meals: it reduces appetite and slows the emptying of the stomach, and these medicines are approved to treat type 2 diabetes and obesity. [25], [16], [26]

The GLP-1 medicines discussed alongside TRT include semaglutide (Ozempic, Wegovy, and the tablets Wegovy and Rybelsus), tirzepatide (Mounjaro, Zepbound), which also acts on a second gut-hormone receptor called GIP, and liraglutide (Saxenda, Victoza). Orforglipron (Foundayo), a daily GLP-1 pill, was approved in the US in April 2026. Retatrutide, often discussed alongside TRT online, is not approved anywhere. Checked September 2026. [16], [17], [27], [28], [29]

Men combine them for three main reasons: to lose weight hoping their own testosterone recovers (extra body fat lowers it), to lose weight while already on TRT, or because they were offered one instead of the other. Each medicine has been studied in thousands of people, but no randomized trial has tested them together, and the registered trials we found compare them rather than combine them. [30], [31], [32]

TRT and GLP-1 medicines: the key numbers

No guideline sets a number for combining the two medicines. What guidelines address is the order of steps when excess weight is behind low testosterone. Most put weight loss first; two pair lifestyle change with testosterone. This table shows what each body says, checked in September 2026.

[6], [25], [10], [7], [8], [9], [33], [21], [11], [34], [35], [36]

Most bodies (the Endocrine Society, EAU, EAA, the Brazilian societies and ESA) put weight loss first when excess weight is behind low testosterone; the AUA and BSSM pair lifestyle change with testosterone instead. None recommends testosterone as a treatment for weight or diabetes. They differ because they weigh different things. The weight-loss-first bodies treat weight-related low testosterone as functional: a problem that can reverse when its cause is treated, because weight loss raises a man's own testosterone. The BSSM points to a trial in which only men given testosterone during a diet kept their lean muscle and felt better, and argues that men with symptoms need relief now. The EAU adds that the rise from diet and exercise is small and that most lost weight comes back within a few years. [6], [7], [11]

Only the ICSM 2024 recommendations mention GLP-1 medicines. No guideline gives rules for taking a GLP-1 medicine with TRT, and the EAA is the only body that mentions stopping TRT after weight loss. [34], [8]

Why don't guidelines say more?

Because the combination is newer than most of the guidance: several of these documents date from 2018 to 2020, before the first studies of men taking both. Testosterone trials shaped them instead. In T4DM, testosterone injections given with a lifestyle program cut new diabetes at 2 years to 12% vs 21% on placebo, while in TRAVERSE, testosterone gel without a structured program did not significantly slow the move from prediabetes to diabetes. [10], [25], [8], [37], [38]

How do the units work?

Testosterone is reported in ng/dL in the US and in nmol/L in most other countries. One nmol/L equals 28.84 ng/dL, so a rise of 2.5 nmol/L is about 72 ng/dL. Estradiol is reported in pg/mL or pmol/L, and SHBG (the protein that carries testosterone in the blood) in nmol/L. The testosterone unit converter switches between units, and the TRT blood work guide explains when to draw each test.

How do GLP-1 medicines change testosterone?

Mostly by lifting the brake that extra body fat puts on your own testosterone production. That only works while your own production is running, which is why the picture changes once you are on TRT.

Why does extra weight lower testosterone?

Testosterone production is controlled by a chain of signals: the brain and pituitary gland send two hormones, LH and FSH, to the testes, which answer with testosterone and sperm. In men with obesity this chain often runs low, a pattern doctors call obesity-related or functional hypogonadism. Weight loss turns it back up: in a 2013 meta-analysis, weight loss raised testosterone, SHBG and the pituitary hormones, with bigger losses giving bigger rises. [30]

How much? In that meta-analysis of 24 studies, total testosterone rose about 2.9 nmol/L (about 83 ng/dL) with a low-calorie diet and 8.7 nmol/L (about 250 ng/dL) after weight-loss surgery. A long-term study found men's testosterone rose about 0.6% for each kilogram lost. [30], [44]

Guidelines put the gain from diet at different sizes. The Endocrine Society of Australia says a 10% weight loss raises testosterone by 2–3 nmol/L (about 58–87 ng/dL). The EAU calls the rise after a low-calorie diet and exercise small; it puts the gain at about 1–2 nmol/L (about 29–58 ng/dL) and notes that 60–86% of lost weight is regained within three years. Part of the gap is what each describes: the ESA figure assumes a 10% weight loss, while the EAU describes typical diet and exercise programs. [35], [7]

Total and free testosterone do not move equally. In the European Male Ageing Study (2,395 men followed for 4.4 years), weight loss raised total testosterone and SHBG together, and free testosterone changed significantly only in men whose weight changed by 15% or more. [45]

Is it the weight loss or the medicine?

Reviews disagree. A 2026 review of these medicines found rises of about 2.5–5.2 nmol/L and concluded they were largely explained by weight loss and better insulin resistance rather than a direct effect on the testes. A 2025 meta-analysis of 7 studies (680 men) also found the rise tracked weight loss. A 2026 meta-analysis of 8 studies (375 men) took the opposite view, judging the effect independent of weight loss and suggesting a direct action. [5], [46], [47]

Studies in lean, healthy men point toward weight loss doing most of the work. Four weeks of dulaglutide in normal-weight men with normal testosterone changed neither their hormones nor their sexual desire, and a single dose of exenatide in healthy volunteers caused only a brief, small dip in LH and testosterone two hours later. [48], [49]

What happens to SHBG and free testosterone?

SHBG often rises as weight falls, so total testosterone can rise more than free testosterone. In one liraglutide study, SHBG went from 14 to 36 nmol/L over 4 months. A 2026 review found free testosterone results inconsistent across studies, and a small 2025 meta-analysis found no significant change in free testosterone or SHBG. [50], [12], [51]

What changes once you are on TRT?

Testosterone from outside switches LH and FSH down, so the testes make little of their own. A GLP-1 medicine can only lift a signal that is still running, so on TRT your blood test mostly reflects your dose, when blood was drawn and your SHBG. That is our reading of the physiology, and the closest evidence fits it: in a records study of 11,931 matched men per group, presented at a 2026 urology meeting, testosterone levels did not differ between men on TRT alone and men who also took a GLP-1 medicine. No study has measured SHBG, free testosterone or estradiol in men taking both. [12], [4]

Estradiol, the main estrogen, is made partly from testosterone. In a 2-month tirzepatide pilot in men not on TRT, median estradiol fell from 33 to 11 pg/mL (about 121 to 40 pmol/L), against 33 to 40 pg/mL (about 121 to 147 pmol/L) in a group using testosterone gel; men chose their own treatment, so the groups are not directly comparable. See the estrogen on TRT guide. [52]

What does the research show?

Each medicine has been studied in thousands of people; the combination has not. For men taking both, there are four small or early studies and no randomized trial.

Do GLP-1 medicines raise testosterone in men not on TRT?

Yes, modestly, in men whose low testosterone is linked to their weight: across small, short studies, total testosterone rose by about 2.5–5.2 nmol/L (about 72–150 ng/dL). [5]

The pattern is consistent: the more weight lost and the lower testosterone starts, the bigger the rise. A 2026 network meta-analysis of 23 randomized trials (1,899 men) compared weight loss, GLP-1 medicines, testosterone and other options for obesity-related low testosterone and found no single strategy best on every outcome; testosterone raised hematocrit. [58]

One records study pointed the other way. Among 3,094 matched pairs of men aged 18–50 without diabetes, those prescribed semaglutide for weight loss had more new diagnoses of low testosterone (1.53% vs 0.80%) and erectile dysfunction (1.47% vs 0.32%). It counted diagnosis codes, not blood tests, and it cannot show that semaglutide caused either. [59]

What do studies of men taking both show?

Very little, and nothing randomized. We found four studies of men taking testosterone and a GLP-1 medicine together.

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Every study we found of men taking both medicines

Testosterone plus a GLP-1 medicine: design, size and what each study measured.

1. Giagulli 2015Records study (retrospective)

   43 on testosterone undecanoate + metformin; 26 added liraglutide · 2 years

   Blood sugar, weight, SHBG, testosterone, erectile function improved after adding liraglutide

2. Seminara 2026Pilot

   10 (5 per group) · 6 months

   Adding testosterone to tirzepatide: more fat loss; lean mass 66.1 vs 63.4 kg; erection score 23.2 vs 18.0

3. Mendias 2026Case series, one clinic, no comparison group

   93 aged 40–60 · 12 months

   Weight down about 21–23 kg; lean body mass down 4.0–6.1 kg; estimated muscle up 1.6–3.7 kg (bioimpedance); hematocrit not reported

4. NEAUA 2026Records study, conference abstract

   11,931 per group · not stated

   Testosterone levels no different; erectile dysfunction less common (hazard ratio 0.880)

Randomized trials of the combination: none found (checked Sep 2026)

None randomly assigned men to the combination, so these results show links, not proof that the pair caused them.

• Liraglutide added to testosterone (2015). In a records study of 43 men with obesity, type 2 diabetes and clearly low testosterone, all on testosterone undecanoate injections and metformin, the 26 who responded poorly added liraglutide in the second year and improved their blood sugar, weight, SHBG, testosterone and erectile function. Men got the add-on because they were doing poorly, and some had low testosterone for reasons other than weight. [1]
• Testosterone added to tirzepatide (2026). In a pilot of 10 men who were slow to respond to tirzepatide, the 5 who added testosterone undecanoate injections for 6 months lost more fat, had more lean mass (66.1 vs 63.4 kg) and better erection scores (23.2 vs 18.0) than the 5 who did not. How men were assigned is unclear. [2]
• Tirzepatide, testosterone and coaching (2026). At one clinic, 93 men aged 40–60 took tirzepatide with testosterone cypionate (100 mg a week or less) and lifestyle coaching. Over 12 months they lost about 21 to 23 kg; lean body mass fell 4.0–6.1 kg, while estimated muscle rose 1.6–3.7 kg and grip strength 5.7–7.1 kg. There was no comparison group, muscle was estimated by bioimpedance, and hematocrit was measured but not reported. The authors say the design cannot credit any single part. [3]
• Records study (2026 conference abstract). In a US health-records database, 11,931 men with obesity and low testosterone on TRT alone were matched with 11,931 who also took a GLP-1 medicine. Testosterone levels did not differ (average 420 vs 431 ng/dL, about 14.6 vs 14.9 nmol/L); erectile dysfunction was less common with a GLP-1 medicine added (hazard ratio 0.88; the abstract gives no absolute rates); low libido, infertility and ejaculation problems did not differ. It is a conference abstract and has not been published as a full paper. [4]

The authors of the 2026 meta-analysis of 8 studies wrote that "a combination of TRT and GLP1-RAs can be considered in selected cases", an opinion, not a guideline. The registered trials we found compare semaglutide with testosterone or test GLP-1 medicines for male fertility; none tests the two together. [47], [31], [32]

Do GLP-1 medicines cost muscle, and can testosterone protect it?

Some, yes: roughly a quarter to a third of the weight lost is lean mass, similar to other ways of losing weight. Whether testosterone protects muscle during GLP-1 weight loss has not been properly tested. Lean mass on a DXA body scan is everything that is not fat or bone, including water and organs, so a fall in lean mass is not the same as a fall in strength.

• Tirzepatide. In a SURMOUNT-1 body-scan substudy of 160 adults (73% women), about three quarters of the weight lost over 72 weeks was fat and one quarter lean (74% and 26%), the same split as on placebo (75% and 25%); tirzepatide simply caused far more weight loss (21.3% vs 5.3%). In men, 73% of the loss was fat. MRI scans in another tirzepatide trial showed thigh muscle shrinking in line with the weight lost. [13], [60]
• Semaglutide. In STEP 1 (140 adults, 76% women), lean mass fell 9.7% while fat mass fell 19.3%, reported as a conference abstract. [61]
• Pooled trials. A 2026 meta-analysis of 20 trials (15,782 people) found lean mass made up 35.2% of the weight lost on semaglutide, 25.4% on tirzepatide and 26.8% on liraglutide, against 26.2% with lifestyle change and 17.5% with lifestyle change plus resistance training. [62]

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How much of the weight lost was lean mass

Share of weight lost that was lean mass, by treatment (meta-analysis of 20 randomized trials, 15,782 people).

Bars run from 0% to 40% of the weight lost.

Semaglutide

35.2% of weight lost was lean mass

Liraglutide

26.8% of weight lost was lean mass

Lifestyle change

26.2% of weight lost was lean mass

Tirzepatide

25.4% of weight lost was lean mass

Lifestyle change + resistance training

17.5% of weight lost was lean mass

Lean mass includes water and organs as well as muscle. Bars are pooled averages; ranges are not shown.

What testosterone did during other kinds of weight loss:

• On a very low energy diet, testosterone injections gave 2.9 kg more fat loss and 3.4 kg less lean-mass loss than placebo over 56 weeks, an advantage that was gone 82 weeks after they stopped. [14], [15]
• In T4DM, with every man in a lifestyle program, fat mass fell 4.6 kg on testosterone vs 1.9 kg on placebo over 2 years, and skeletal muscle rose 0.4 kg vs fell 1.3 kg. [63]
• In older men in an intensive lifestyle program, testosterone limited the loss of lean mass and thigh muscle but did not improve strength or physical function, and it added no metabolic benefit. [64], [65]

None of these trials used a GLP-1 medicine. Resistance training has better support (see protecting muscle), and the TRT, muscle and fat loss guide covers training on TRT.

What about erections, libido and fertility?

The erection data point both ways and are almost all observational. On the positive side, adding a GLP-1 medicine to metformin raised erection scores 2.26 points over a year in men with diabetes and erectile dysfunction. Tirzepatide was linked with less erectile dysfunction than injectable semaglutide (relative risk 0.67; the abstract gives no absolute rates). And on TRT, adding a GLP-1 medicine went with less erectile dysfunction in the conference records study. [66], [67], [4]

On the negative side, the semaglutide records study above found more new erectile dysfunction. In men with type 2 diabetes, GLP-1 starters were diagnosed with erectile dysfunction at 35.2 vs 28.0 per 1,000 person-years compared with starters of another diabetes medicine (hazard ratio 1.26), but the link weakened and was no longer significant after a check for hidden bias. Side-effect reports also gave a signal for semaglutide. A 2026 meta-analysis reporting better erection scores gives search dates that had not yet happened, so treat it with caution. [59], [68], [69], [70]

Libido has almost no data. Dulaglutide did not change sexual desire in healthy men, and low libido was no more common with a GLP-1 medicine added to TRT in the records study. In TRAVERSE, testosterone raised desire in men with low libido but did not improve erections. See the TRT and sexual health guide. [48], [4], [71]

Fertility differs sharply between the two medicines. Testosterone therapy suppresses sperm production, so the AUA says it should not be prescribed to men trying to conceive. GLP-1 medicines did not suppress sperm in small studies: sperm shape improved on semaglutide while testosterone injections lowered sperm concentration, sperm motility rose from 14% to 34% on liraglutide in a nonrandomized study, and sperm-count gains from dieting held in men who kept the weight off with exercise or liraglutide. The EU labels say the effect on human fertility is unknown, and no study has counted pregnancies or births. See TRT and fertility. [10], [54], [50], [72], [39], [40]

Is it safe to take TRT and a GLP-1 medicine together?

Nobody knows for certain, because no study has tested the safety of the combination. Each medicine has a well-studied safety record on its own, no label lists an interaction between them, and their known risks overlap in a few specific places. [16], [17], [27], [73]

Where do the risks overlap?

• Heart rate and rhythm. GLP-1 labels report resting heart rate rising 1 to 4 beats per minute on Wegovy, 2 to 3 on Ozempic and Saxenda, 1 to 3 on Zepbound and 2 to 4 on Mounjaro; in the SURPASS-CVOT trial, tirzepatide raised average heart rate by up to 6 beats per minute. In its phase 2 trial, retatrutide raised heart rate in a dose-dependent way, peaking at 24 weeks (see the retatrutide guide). [74] In TRAVERSE, testosterone gel increased atrial fibrillation and other rhythm problems (see below). No study has measured heart rate or rhythm on both. [16], [19], [27], [17], [26], [40], [18]
• Kidneys. GLP-1 labels warn that vomiting, diarrhea and dehydration can injure the kidneys and advise checking kidney function when these side effects are severe. Testosterone gel increased acute kidney injury in TRAVERSE (see below). [16], [40], [18]
• Blood sugar. Testosterone labels say testosterone may lower blood sugar in people with diabetes, so doses of insulin or other diabetes medicines may need lowering. GLP-1 labels warn that low blood sugar (hypoglycemia) is more likely when they are combined with insulin or a sulfonylurea. [41], [42], [18], [19], [26]
• Red blood cells. Testosterone raises hematocrit; GLP-1 medicines have not been shown to lower it (see Does a GLP-1 medicine lower hematocrit?). The diabetes medicines that add to the rise are SGLT2 inhibitors, covered below. [37], [20], [75]
• Sleep apnea. This overlap can work in your favor. Zepbound is approved to treat moderate to severe obstructive sleep apnea with obesity; at 52 weeks, breathing pauses fell by 25.3 vs 5.3 events an hour in people not using a breathing machine. Testosterone can make apnea worse for a while: injections worsened nighttime oxygen drops at 7 weeks (not at 18) in obese men with severe apnea, and new apnea diagnoses were more common on testosterone during T4DM (3.0% vs 0.4%). [76], [77], [78], [79]
• Tiredness and mood. Fatigue is a listed GLP-1 side effect (see tiredness). In pooled liraglutide trials, depression (2.1 vs 2.1 events per 100 person-years) and anxiety (1.9 vs 1.7) were no more common than on placebo. [80]

What did TRAVERSE and the GLP-1 heart trials show?

No trial has tested heart safety for the combination, and the results of separate trials cannot simply be added together.

TRAVERSE is the largest trial of testosterone and heart safety: 5,204 men aged 45–80 with low testosterone and existing heart disease or high heart risk used a daily testosterone gel or a placebo gel. Heart attack, stroke or cardiovascular death occurred in 182 of 2,596 men on testosterone (7.0%) and 190 of 2,602 on placebo (7.3%) (hazard ratio 0.96), which met the trial's safety goal. Atrial fibrillation (3.5% vs 2.4%), other rhythm problems needing treatment (5.2% vs 3.3%), acute kidney injury (2.3% vs 1.5%) and pulmonary embolism (0.9% vs 0.5%) were more common on testosterone. In a substudy, clinical fractures were also more common: 91 of 2,601 men (3.50%) vs 64 of 2,603 (2.46%), hazard ratio 1.43. Its limits: it tested only a gel, men used it for an average of 21.7 months, and about 61% stopped their study gel early. [73], [18], [81]

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TRAVERSE: absolute results

Testosterone gel (2,596 men)Placebo gel (2,602 men)

Heart attack, stroke or heart death

Testosterone 7.0% vs placebo 7.3% (182 vs 190 men; hazard ratio 0.96, 95% CI 0.78–1.17; met the 1.5 safety margin)

Nonfatal rhythm problems needing treatment

Testosterone 5.2% vs placebo 3.3%

Atrial fibrillation

Testosterone 3.5% vs placebo 2.4%

Clinical fracture

Testosterone 3.5% vs placebo 2.5% (91 of 2,601 vs 64 of 2,603 in the full analysis set)

Acute kidney injury

Testosterone 2.3% vs placebo 1.5%

Venous clots (all)

Testosterone 1.7% vs placebo 1.2%

Pulmonary embolism

Testosterone 0.9% vs placebo 0.5%

About 5,200 men aged 45–80 at high heart risk; daily gel; mean treatment 21.7 months; about 61% stopped their study gel. Not a trial of injections.

The GLP-1 heart trials tested their own medicines. In SELECT, 17,604 people aged 45 or older with heart disease and a BMI of 27 or more, but no diabetes, took semaglutide or placebo: heart attack, stroke or cardiovascular death occurred in 6.5% vs 8.0% (hazard ratio 0.80). In SURPASS-CVOT, in people with type 2 diabetes, tirzepatide matched dulaglutide (12.2% vs 13.1%, hazard ratio 0.92), meeting its goal of not being worse but not proving it better. The TRT and heart health guide covers TRAVERSE in full. [82], [83]

Who should be especially cautious?

• Men who use insulin or a sulfonylurea, because both medicines can lower blood sugar. [41], [19]
• Men with a fast heart rate, atrial fibrillation or other rhythm problems, because GLP-1 medicines raise heart rate and testosterone raised atrial fibrillation in TRAVERSE. [16], [18]
• Men with kidney disease or who get dehydrated easily, especially while vomiting or diarrhea last. [16]
• Men taking oral testosterone, men with a high hematocrit and men taking an SGLT2 inhibitor. [42], [75]
• Men with untreated severe sleep apnea. The Endocrine Society and the VA advise against starting testosterone; Zepbound is an approved treatment for the apnea itself. [25], [21], [17]
• Men trying to conceive. Testosterone suppresses sperm production; the AUA advises against it, and the BSSM calls an active wish for children a main contraindication. [10], [11]
• Men using products from outside a pharmacy, whose content is unknown (see compounded and "research" products). [29]
• Men with the conditions GLP-1 labels warn about, which the semaglutide and tirzepatide guides cover.
• Drug-tested athletes. Testosterone is prohibited in sport at all times. [23]
• Under-18s. Testosterone for teenagers belongs only in specialist care.
• Women. This guide is written for men. Testosterone for women uses different doses and products; see testosterone therapy for women.

Which medicines interact?

• Testosterone and GLP-1 medicines. None of the current US labels for Wegovy, Ozempic, Zepbound, Mounjaro or Saxenda, nor the EU product information for Wegovy and Mounjaro, lists an interaction with testosterone. That means none has been identified, not that the pair has been tested. [16], [19], [17], [26], [27], [39], [40]
• Oral medicines, insulin and sulfonylureas. GLP-1 labels ask for care with oral medicines, which matters for oral testosterone, and warn about low blood sugar with insulin or a sulfonylurea. [16], [19], [26]
• Two GLP-1 medicines at once. The Saxenda label says not to combine it with any other GLP-1 receptor agonist; some men in forums take two at the same time. [27], [84]
• SGLT2 inhibitors (such as empagliflozin and dapagliflozin). These diabetes and heart medicines raise hematocrit: SGLT2 starters had hematocrit 1.50 points higher than GLP-1 starters, and in US veterans with diabetes, adding an SGLT2 inhibitor to testosterone gave about 2.5 times the odds of hematocrit above 54% within a year compared with testosterone alone (adjusted odds ratio 2.49). Across all 53,971 veterans in that study, 756 (1.4%) reached that level; the abstract does not give each group's rate. UK testosterone labels now warn about the combination, and an EU safety review in September 2025 recommended adding the warning to all testosterone products. [85], [75], [86], [87]

Bring a complete list of what you take, including supplements, to a pharmacist or prescriber. Checked September 2026.

What about compounded and "research" GLP-1 medicines?

In the US, the shortage-era allowance for mass-compounded semaglutide and tirzepatide has ended: FDA declared the tirzepatide injection shortage resolved on 19 December 2024 and the semaglutide shortage on 21 February 2025, and compounded drugs are not FDA-approved. In February 2026 FDA announced action against non-approved GLP-1 drugs, and in April 2026 it proposed stopping outsourcing facilities from compounding semaglutide, tirzepatide and liraglutide from bulk ingredients, a proposal that is still pending. Checked September 2026. [88], [89], [90]

Retatrutide is not approved anywhere. FDA says it cannot be used in compounding and is not a component of any approved drug, and it has warned sellers of GLP-1 products falsely labeled "for research purposes" or "not for human consumption". Lilly has said it plans to submit retatrutide to the FDA in the first quarter of 2027. A product sold for research use only has not been tested for human use, which adds one more unknown to every lab result and side effect. [29], [91]

Is it legal, and is it allowed in sport?

Checked September 2026. Rules differ by country and change often.

• United States. Testosterone and its esters are Schedule III controlled substances, prescription only. GLP-1 medicines are prescription only; recent approvals include Wegovy tablets (December 2025), Wegovy HD (March 2026) and Foundayo (April 2026). [22], [92], [93], [28]
• United Kingdom. Testosterone is a Class C controlled drug. [94]
• Canada. Testosterone is a Schedule IV controlled substance. [95]
• Australia. Testosterone is a Schedule 4 prescription-only medicine. [96]
• European Union. Wegovy and Mounjaro are approved EU-wide. [39], [40]
• Sport. The World Anti-Doping Agency (WADA) prohibits testosterone at all times, and its 2027 list keeps the ban. An exemption for medical use is granted only for low testosterone with a clear medical cause, not for low testosterone linked to obesity. Semaglutide and tirzepatide are on WADA's Monitoring Program for 2026 and 2027, which means WADA tracks their use but does not ban them. Retatrutide is not named, but the list bans any substance with no current approval for human use, which by its wording covers retatrutide. [23], [97], [98], [99], [24]

What do guidelines say to do?

Guidelines describe the order of steps rather than how to combine the medicines. For a man whose low testosterone is weight-related and who has not started TRT, most favor treating the weight first and retesting, while the AUA and BSSM pair lifestyle change with testosterone (see the key numbers). For a man already on TRT who adds a GLP-1 medicine, no guideline changes the usual TRT monitoring. This table summarizes the other choices clinicians weigh; it is not a personal plan. [6], [7], [8], [10], [11]

[34], [25], [21], [9], [35], [10], [11]

Practical questions about taking both

Should you start a GLP-1 medicine or TRT first?

When excess weight is the likely cause of low testosterone, most guidelines put weight loss first, and a GLP-1 medicine is one way to get there. Testosterone may no longer be low after large weight loss, so starting TRT first can make it hard to know whether you still need it. TRT suppresses sperm production, while GLP-1 medicines did not in small studies. And starting one medicine at a time makes it easier to tell which one caused a change. [6], [7], [57], [10], [54]

Men with low testosterone from a testicular or pituitary problem are a different case: weight loss will not fix that. The Endocrine Society of Australia says testosterone that stays low despite successful weight loss should prompt a search for another cause. [35]

Will a GLP-1 medicine change your testosterone results on TRT?

Probably not much for injections and gels: in the large records study, testosterone levels did not differ between men on TRT alone and men who added a GLP-1 medicine. SHBG tends to rise as weight falls, so total and free testosterone may move differently, although nobody has measured this in men taking both. Oral testosterone is the exception, because its absorption depends on meals (see below). [4], [45]

Some men report much higher results after large weight loss on the same dose. In one forum account, total testosterone went from 1,265 to 2,678 ng/dL (about 44 to 93 nmol/L) over two years on TRT and tirzepatide, but the sample was drawn 36 to 40 hours after an injection and the cause was not established. Have blood drawn at the time your product's label or your guideline specifies, so results can be compared; the testosterone level visualizer shows how injection timing changes peaks and troughs. [102]

How long after weight loss should testosterone be rechecked?

No study sets a time. Testosterone rose within 2 months in the tirzepatide pilot, and the exenatide cohort measured it at 6 months. The VA says significant weight loss or gain may prompt earlier testosterone checks, and some forum posters wait until their weight has been stable for a few months. [52], [56], [21], [103]

For a man already on TRT, his own production can only be measured after stopping. In a pilot of severely obese men, the 12 who took testosterone during a diet were back to low testosterone within 24 weeks of stopping it. [100]

Can you stop TRT after losing weight?

Sometimes, but the evidence is thin, and nobody has studied it after GLP-1 weight loss. The EAA says "TRT withdrawal may be considered following weight reduction"; no other guideline addresses it. [8]

• In a pilot of 24 severely obese men on a diet with or without testosterone undecanoate for 54 weeks, stopping testosterone meant "a return back to hypogonadism within 6 months". Fat loss held, but lean-mass gains were lost. [100]
• In a case report, one man stopped testosterone after weight-loss surgery (he lost 53% of his weight) and later measured 15.8 nmol/L (about 456 ng/dL) without treatment. [101]
• About five years after T4DM, 6% of former testosterone users and 2.8% of former placebo users had restarted testosterone. [79]

Whether it works depends on why testosterone was low in the first place. The stopping TRT guide covers what happens when testosterone stops, and the obesity-related hypogonadism guide covers weight-related low testosterone.

How should oral testosterone be taken with a GLP-1 medicine?

With a meal, as its label says, and with a blood test after the GLP-1 medicine starts or its dose goes up. No study has tested the pair, so this comes from the two sets of labels.

• Food matters for oral testosterone undecanoate. It is absorbed with dietary fat through the lymphatic system. Jatenzo taken with a 15 g fat breakfast gave 25% less testosterone than with a 30 g fat breakfast; Kyzatrex exposure was 37%, 87% and 94% higher with 16%, 33% and 45% fat breakfasts than fasting; and fasting cut Tlando's peak level by about 65% and total exposure by about 38%. [42], [18], [43]
• GLP-1 medicines slow the stomach. Their labels ask for closer monitoring of some oral medicines, most of all when starting and after each dose increase. This applies to medicines that need a certain blood level to work or that require clinical monitoring. Oral testosterone's dose is set by blood tests: drawn 6 hours after the morning dose for Jatenzo, 3–5 hours for Kyzatrex and 8–9 hours for Tlando. So it fits that description, although no label names it. [16], [17], [40], [42], [18], [43]
• If your GLP-1 medicine is a tablet. Wegovy tablets must be taken at least 30 minutes before food, drinks or other oral medicines, which clashes with taking oral testosterone at breakfast. Foundayo does not need to be taken on an empty stomach. No study sets a spacing between the two. [16], [28]

The oral testosterone guide covers each product in detail.

Does a GLP-1 medicine lower hematocrit on TRT?

No study shows that it does, and no study reports hematocrit in men taking both. On a GLP-1 medicine alone, hematocrit did not change significantly (45.1% to 45.7% over 6 months on semaglutide), and in the trial comparing semaglutide with testosterone injections it moved about 1 point in both groups. Some records studies found slightly lower hemoglobin or more anemia on GLP-1 medicines: in one, of 700 users with no comparison group, median hemoglobin fell 0.2 g/dL and 59 (8.4%) developed anemia. A 2026 review found the evidence not enough to show that the medicines cause it. The hematocrit on TRT guide covers what does lower hematocrit. [20], [54], [104], [105], [106]

Is it the GLP-1 medicine or low testosterone making you tired?

It can be either, or simply eating too little, and only a blood test can show whether testosterone is low. Fatigue is a listed GLP-1 side effect (Wegovy 11% vs 5% on placebo; Zepbound 5–7% vs 3%; Saxenda 7.5% vs 4.6%), and low energy is a common symptom of low testosterone. In forums, men describe exhaustion on a GLP-1 medicine while their measured testosterone was rising, and tiredness that faded after the first weeks of tirzepatide. No trial has tested TRT for tiredness on a GLP-1 medicine. [16], [17], [27], [25], [107], [108]

The same goes for sex drive: a drop in desire that starts with a GLP-1 medicine has not been studied, and in TRAVERSE, testosterone raised desire but not erections in men with low testosterone and low libido. [109], [71]

How can you protect muscle while losing weight?

Resistance training has the best evidence; protein is being tested. In pooled trials, lifestyle change with resistance training had the smallest lean share of weight lost (17.5%). In a trial after dieting, exercise plus liraglutide kept weight off best and cut body fat by 3.9 percentage points. A trial now under way is testing 1.6 g of protein per kilogram of body weight a day, resistance training or both on semaglutide and tirzepatide, with no results yet. [62], [110], [111]

Many men on a GLP-1 medicine struggle to eat enough protein because their appetite is so low (see what people report). The whey protein guide covers one common option.

What do men report when they combine TRT and a GLP-1 medicine?

Public forums are full of men combining testosterone with semaglutide, tirzepatide or, very often, retatrutide bought outside a pharmacy. The threads below are public Reddit discussions from September 2025 to September 2026, read with their replies; they show what people experience, not how often it happens. Accounts involving testosterone doses well above replacement (steroid cycles) are not TRT and are left out.

Which came first, and did it matter?

Men are often torn. One man with testosterone around 370 ng/dL (12.8 nmol/L) was advised by two clinicians to try a GLP-1 medicine before TRT, and most replies favored losing weight and retesting. [112] Another, at 296 ng/dL (10.3 nmol/L) with sleep apnea, was offered Zepbound and worried about fertility if he chose TRT instead. [113] A man weighing both agreed that trying one treatment at a time would make each easier to judge, and in another thread a reply described TRT as easier to tolerate after losing weight on tirzepatide. [114], [115]

Did weight loss raise testosterone on its own?

Sometimes. One man went from 289 to about 196 lb on Zepbound, and his repeatedly low total testosterone (216–237 ng/dL, 7.5–8.2 nmol/L) rose to 521 ng/dL (18.1 nmol/L) without TRT while his sleep apnea was also treated; one reply described a similar rise and another said testosterone stayed low despite major weight loss. [116] Men who had lost from 20 to more than 60 kg planned to retest once their weight settled, and wondered whether an ongoing calorie deficit was holding their result down. [103], [117] A rising number did not always mean feeling better: two men whose testosterone rose during GLP-1 weight loss still had fatigue, and one also low libido. [118], [107]

What happened when TRT started after a GLP-1 medicine?

Scale weight often went up first. One man lost 42 lb on retatrutide, then gained 7 lb and felt hungry all the time in his first two weeks of self-prescribed testosterone; replies pointed to early water retention. [119] Another's hunger and weight gain began to settle by about week 10. [120] Some started TRT because of what the weight loss cost them: one man's body scan suggested nearly 10 lb of the 35 lb he lost on retatrutide was muscle, as his libido, motivation and strength fell. [121]

What do the success stories look like?

The strongest accounts involve long efforts with many changes at once. One man with severe obesity, poorly controlled diabetes, very low testosterone and severe sleep apnea started Mounjaro and testosterone together after losing 20 lb on his own; about 9 months later he had gone from about 365 to 240 lb and his HbA1c from 11.6 to 5.6, with regular training. [122] Another went from 330 to 220 lb over nearly two years, losing the first 50 lb without medicines. [123] Nonresponse appears too: one man saw no weight change after six months of TRT, and another's weight loss stalled on both medicines when joint pain cut his training. [124], [125]

What happened to muscle and strength?

Accounts split. A man on TRT for five years added retatrutide for four months, went from 111 to 99 kg, felt healthier and watched his main lifts fall substantially, with protein intake that varied on one meal a day. [126] Another lost 83 lb over 14 months on TRT and a GLP-1 medicine while lifting, and lost some strength and muscle. [127] Early scan changes are hard to read: replies noted that lean mass rising three weeks into TRT, or muscles feeling flat after fast early weight loss, often reflect water. [128], [129] Eating enough protein is the recurring struggle, with men relying on shakes and small protein-rich meals. [130], [131]

What side effects come up?

• Stomach. One man on TRT raised semaglutide to 0.75 mg and had severe bloating, nausea and repeated vomiting until he dropped back; another became nauseated whenever either injection was due, which disrupted his testosterone schedule. [132], [133]
• Heart rate. A woman described her partner's resting heart rate rising during retatrutide he managed himself, and replies in several threads report higher resting heart rates on retatrutide. [134], [135], [136]
• Mood. One man had detachment and panic attacks days after adding retatrutide to a new, underground testosterone source, which left the cause unclear; another said anhedonia (an inability to enjoy things) on a higher retatrutide dose went away after he lowered it. [137], [138]
• Libido. A man with long-standing low testosterone lost desire and erections after starting the lowest dose of Mounjaro, with his testosterone unchanged; a reply said tirzepatide dampened his desire and TRT raised it somewhat. [109]

Are serious problems reported?

Some posts describe worrying symptoms, but selected accounts cannot show how often they happen or what caused them. One man developed chest burning or pressure after raising his testosterone and retatrutide doses at the same time; his blood pressure rose from about 116/70 to about 135/85, an ECG was described as normal, and later blood work showed a hematocrit of 0.55. The cause was not established. [139] Chest pain or pressure needs prompt medical assessment, not a forum answer.

What do lab results on both medicines look like?

They are hard to read because several things usually change at once. One man's hematocrit went from 50.1% to 48.1% over two years of weight loss on TRT and tirzepatide while his testosterone roughly doubled (see above). [102] Another had hematocrit of 52% while taking two GLP-1 medicines at once; replies said their own hematocrit had not changed on GLP-1 medicines. [84] One man's testosterone jumped and estradiol fell after he added retatrutide, hCG and dutasteride and raised his dose in the same month; replies pointed to the hCG and dutasteride. [140] Replies about SHBG, and about whether retatrutide affects labs, disagreed. [141], [142]

What about products bought outside a pharmacy?

Many threads involve retatrutide or other GLP-1 medicines from unregulated sellers, with men asking whether they bought a fake product or were cheated by a supplier. When a product's content is unknown, no lab result or side effect can be pinned on it with confidence (see compounded and "research" products). [143], [144]

How can you judge a TRT and GLP-1 story?

Ask: Was the testosterone prescribed, and at a replacement dose? Was the GLP-1 an approved product from a pharmacy? What else changed at the same time: diet, training, alcohol, sleep apnea treatment, other drugs such as hCG? Was the change measured on a scale, a home device or a DXA scan, and could water explain it? Were blood tests drawn at the same point in the dosing schedule? How long had each medicine been taken? And what happened next?

These selected discussions show what people experience and the questions research has not answered. They are not a survey of all men taking both medicines, a success rate or a substitute for the studies above.

What should you track?

The usual monitoring for each medicine still applies, plus a few checks where they overlap. Use this summary to prepare questions for your prescriber; it is not a personal testing plan.

[25], [21], [16], [18], [19], [41], [13], [10]

Draw timing, hydration and weight change all move the numbers, so a trend of results drawn under similar conditions says more than any one test. The TRT blood work guide covers when to draw each test.

Common questions about TRT and GLP-1 medicines

Can you take TRT and Ozempic (or another GLP-1 medicine) at the same time?

Yes. Doctors do prescribe both (one US records database held nearly 12,000 men taking TRT and a GLP-1 medicine), and no label lists an interaction between them. But the combination has never been tested in a randomized trial, so its safety rests on each medicine's own record. Watch heart rate, kidney strain from vomiting or diarrhea, low blood sugar with insulin, and absorption of oral testosterone. [16], [19], [17], [4] See where the risks overlap.

Will semaglutide or tirzepatide raise my testosterone?

If you are not on TRT and your low testosterone is linked to your weight, probably a little: small studies found rises of about 2.5–5.2 nmol/L (72–150 ng/dL), bigger with more weight lost. If you are on TRT, your own production is switched down, so your result mostly reflects your testosterone dose; a large records study found no difference in testosterone between men on TRT alone and men who added a GLP-1 medicine. [5], [55], [4] See how they change testosterone.

Should I try a GLP-1 medicine before starting TRT?

If excess weight is the likely cause of your low testosterone, most guidelines favor weight loss first (the AUA and BSSM pair lifestyle change with testosterone), and a GLP-1 medicine is one way to get there. Retesting afterward shows whether testosterone is still low, and holding off on TRT protects sperm production. If low testosterone has another cause, weight loss will not fix it. [6], [7], [35], [10], [11] See which comes first.

Can I come off TRT after losing weight on a GLP-1 medicine?

Possibly, but it has not been studied after GLP-1 weight loss. The EAA says stopping may be considered after weight reduction. In a small pilot, 12 severely obese men on a diet plus testosterone were back to low testosterone within 6 months of stopping it; one man in a case report kept a normal level after weight-loss surgery. [8], [100], [101] See stopping after weight loss.

Does TRT prevent muscle loss on a GLP-1 medicine?

It has not been properly tested. In a diet trial without a GLP-1 medicine, testosterone reduced lean-mass loss by 3.4 kg over 56 weeks, but the benefit was gone after it stopped. With a GLP-1 medicine there is only a 10-man pilot and a 93-man clinic series without a comparison group. Resistance training has the best evidence. [14], [15], [2], [3], [62] See muscle and lean mass.

Is retatrutide safe to take with TRT?

Nobody knows. Retatrutide is not approved anywhere, it has never been studied with testosterone, and no human study has reported its effect on male hormones. FDA says it cannot be compounded and has warned sellers of products labeled for research use. Lilly plans to submit it to the FDA in 2027. [29], [91] See compounded and "research" products and the retatrutide guide.

Glossary

Plain explanations of the medical, lab and research terms used in this guide. Underlined terms in the text link here.

Atrial fibrillation

An irregular, often fast heart rhythm that starts in the heart's upper chambers. It raises the risk of stroke and was more common on testosterone gel in TRAVERSE.

Bioimpedance

A body-composition estimate made by passing a tiny electrical current through the body. It is quick but less precise than a DXA scan, and shifts in body water can change its muscle estimates.

Cohort study (records study)

A study that follows a group of people, or looks back at their records, without assigning treatments. It can show links but not prove that one thing caused another.

Compounding

When a pharmacy prepares a customized medicine from individual ingredients. Compounded medicines are not FDA-approved, and in the US the shortage-era allowance to mass-compound semaglutide and tirzepatide has ended.

Conference abstract

A short summary of a study presented at a medical meeting. It has usually not been fully peer reviewed, so it is weaker evidence than a published paper.

Controlled trial

A study that compares people who receive a treatment with a similar group who do not, often receiving a placebo instead. Randomly assigning people to each group makes the comparison fairer.

DXA scan

Dual-energy X-ray absorptiometry: a low-dose X-ray scan that splits the body into fat, bone and lean mass. It is the standard body-composition measure in trials.

Estradiol

The main form of estrogen. In men it is made mostly from testosterone, so it rises when testosterone rises.

Free testosterone

The small share of testosterone in the blood that is not bound to proteins and is available to tissues. It is measured or calculated from total testosterone, SHBG and albumin.

Functional hypogonadism

Low testosterone caused by something that can change, such as obesity, rather than by damage to the testes or pituitary gland. It may improve when the cause is treated.

GIP

Glucose-dependent insulinotropic polypeptide, a second gut hormone that helps control blood sugar. Tirzepatide acts on both the GIP and GLP-1 receptors.

GLP-1 receptor agonist (GLP-1 medicine)

A medicine that acts like GLP-1, a hormone the gut releases after meals. These medicines reduce appetite, slow stomach emptying and lower blood sugar. Examples are semaglutide, tirzepatide, liraglutide and orforglipron.

Hazard ratio

A measure comparing how often an event happens over time in two groups. A hazard ratio of 1 means no difference; 0.96 means about 4% lower in the first group.

Hematocrit

The share of the blood made up of red blood cells. Testosterone therapy can raise it, which is why it is checked.

Hypoglycemia

Blood sugar that is too low, causing shakiness, sweating, confusion or, if severe, fainting. It is mainly a risk for people taking insulin or a sulfonylurea.

Lean mass

Everything in the body that is not fat or bone, including muscle, organs and water. A fall in lean mass is not the same as a fall in muscle strength.

LH and FSH

Luteinizing hormone and follicle-stimulating hormone: the pituitary gland's two signals to the testicles, telling them to make testosterone and sperm. Testosterone therapy switches them down.

Meta-analysis and systematic review

A systematic review gathers all studies on a question in a planned way. A meta-analysis combines their results statistically. A network meta-analysis compares several treatments at once, even ones never tested head to head.

Obstructive sleep apnea

Repeated blocking of the airway during sleep, causing pauses in breathing and drops in oxygen. Loud snoring and daytime sleepiness are common signs.

Odds ratio

A measure comparing the odds of an outcome in two groups. An odds ratio of 2 means roughly twice the odds; 1 means no difference.

Placebo

A dummy treatment with no active ingredient, used as a comparison in studies.

Product label (prescribing information)

The official document approved by a medicines regulator for a product, describing its approved uses, doses, warnings and side effects. In the UK it is called the summary of product characteristics.

Relative risk

How much more or less likely an event is in one group than another. A relative risk of 0.67 means about a third less likely; 1 means no difference.

Research use only

A label on products sold for laboratory research. It does not mean a product is approved, tested for human use or legal to sell as a medicine.

SGLT2 inhibitor

A group of diabetes, heart and kidney medicines, such as empagliflozin (Jardiance) and dapagliflozin (Farxiga), that make the kidneys remove sugar in urine. They raise hematocrit on their own.

SHBG (sex hormone-binding globulin)

A blood protein that carries testosterone. Testosterone bound to it is not immediately available to tissues, so SHBG affects how much free testosterone there is. It tends to be low with obesity and to rise with weight loss.

TRT (testosterone replacement therapy)

Prescribed testosterone, by injection, gel or other forms, for men with low testosterone. It switches down the pituitary's LH and FSH signals.

WADA

The World Anti-Doping Agency, which publishes the list of substances banned in sport. Testosterone is prohibited at all times.

How this guide was researched

This guide is built from a thorough review of the sources cited throughout it: clinical guidelines and position statements, product labels from the US and the EU, published trials and studies, trial registries and regulatory documents. We also reviewed public online forums where men describe taking testosterone and GLP-1 medicines together.

The guide cites 144 sources, including 49 original studies in people, 12 clinical guidelines and position statements, 31 product labels and regulatory or anti-doping documents, and 39 public community discussions. Each type of source answers a different question. Guidelines and labels show what clinicians are told to do. Trials and studies show what was measured. Personal accounts show what individual people experienced. Every numbered citation links to its entry below, labeled by source type.

How this guide was made

Research and drafting were AI-assisted. Every cited source was checked against the original, and the guide was reviewed and edited by Doserly before publication. It has not had an independent clinical review, and Doserly does not currently have medical reviewers. Doserly makes a medication and health-tracking app and runs Doserly Academy, both of which are promoted in this guide. Read our editorial policy for how guides are researched, updated and corrected.

This guide is for educational purposes. It summarizes what the reviewed sources report so the research is easier to understand; it is not medical advice. For a deeper dive, or to check any point for yourself, go straight to the cited sources.

Explore the sources