Most men do not start Ozempic or Mounjaro because they are worried about testosterone. They start because their blood sugar is climbing, their weight has become difficult to manage, or both.
Then something unexpected sometimes happens. After losing weight, a man feels more energetic. His sex drive returns. Morning erections become more frequent. A blood test shows that his testosterone has increased. If he and his partner have been trying to conceive, he may begin wondering whether the medication could improve his sperm as well.
That question has recently moved from online forums into serious medical research.
Early studies suggest that GLP-1 medications may raise testosterone and improve certain measures of sperm health in some men—particularly those with obesity, type 2 diabetes, and obesity-related low testosterone. The findings are encouraging, but they are still preliminary. Ozempic and Mounjaro are not approved treatments for testosterone deficiency or male infertility, and researchers have not yet shown that taking either drug leads to more pregnancies or live births.
So, what do we actually know?
The short answer
Ozempic and Mounjaro may help increase testosterone when a man’s low levels are connected to obesity and poor metabolic health. Much of that benefit probably comes from losing excess fat, improving insulin sensitivity, and reducing the physical stress that obesity places on the hormonal system.
The fertility question is less certain.
A few small human studies involving semaglutide and other GLP-1 drugs have reported improvements in sperm morphology, sperm concentration, or total sperm count. These are meaningful findings, but they do not prove that the medications can treat infertility.
Based on the evidence available today:
- GLP-1 medications are likely to raise testosterone in some men with obesity-related low testosterone.
- They may improve selected sperm measurements, but the evidence remains limited.
- There is no solid proof yet that Ozempic or Mounjaro increases pregnancy or live-birth rates.
- Neither medication is FDA-approved for low testosterone or male infertility.
- Men with normal weight and normal testosterone should not expect a hormonal “boost.”
- The potential benefits are probably much smaller when infertility has a cause unrelated to obesity or diabetes.
The most realistic interpretation is that these drugs may help the reproductive system recover when metabolic illness has been holding it back. That is very different from calling them fertility drugs.
Why obesity can lower a man’s testosterone
Testosterone production depends on a conversation between the brain and the testicles.
The hypothalamus, a small region in the brain, releases a hormone that tells the pituitary gland to produce luteinizing hormone and follicle-stimulating hormone. These are usually called LH and FSH. LH tells the testicles to produce testosterone, while FSH helps support sperm production.
When everything is working normally, this system constantly adjusts itself. When testosterone is low, the brain sends stronger signals. When levels rise, the brain eases off.
Obesity can disrupt that conversation.
Fat tissue is not simply stored energy. It acts almost like an endocrine organ, releasing inflammatory chemicals and influencing hormone metabolism. It also contains aromatase, an enzyme that converts some testosterone into estradiol.
Men need estradiol too, but excess abdominal fat can increase this conversion. Higher estradiol and other metabolic changes may tell the brain that the body has enough sex hormone activity, reducing the signals that stimulate the testicles.
Insulin resistance adds another layer. Men with obesity and type 2 diabetes often have lower levels of sex hormone-binding globulin, or SHBG. This protein carries testosterone through the bloodstream. When SHBG falls, total testosterone may fall with it.
That does not always mean the testicles have permanently failed. Sometimes it means the hormonal system is being suppressed by poor metabolic health.
Poor sleep and obstructive sleep apnea can make the problem worse. So can inflammation, inactivity, certain medications, heavy alcohol use, and the loss of muscle that often accompanies long-term weight gain.
Picture a 40-year-old man who has gained 50 pounds over the past decade. He snores, wakes up tired, has developed prediabetes, and rarely exercises because his knees hurt. His libido is not what it used to be, and a blood test shows low testosterone.
It would be easy to blame age and start testosterone injections. But his testicles may still be capable of producing adequate testosterone. The signals reaching them have become weaker because his entire metabolic system is under strain.
Doctors often call this obesity-related functional hypogonadism. “Functional” means the suppression may be at least partly reversible.
Lose enough weight, improve insulin sensitivity, treat the sleep apnea, and reduce inflammation, and the body may begin producing more of its own testosterone.
That is where Ozempic and Mounjaro enter the story.
What these medications actually do
Ozempic contains semaglutide, a medication that activates the GLP-1 receptor. It is FDA-approved for adults with type 2 diabetes and for reducing certain cardiovascular and kidney risks in appropriate patients.
Wegovy contains the same active ingredient but is approved and dosed for chronic weight management and additional indications. People often use “Ozempic” as a casual name for all semaglutide treatment, although the brands are not medically interchangeable in every situation.
Mounjaro contains tirzepatide and is approved for type 2 diabetes. Zepbound also contains tirzepatide but is approved for chronic weight management and certain obesity-related conditions.
Semaglutide imitates part of the activity of GLP-1, a hormone released after eating. It helps the pancreas release insulin when glucose is elevated, reduces inappropriate glucagon secretion, slows stomach emptying, and affects appetite centers in the brain.
Tirzepatide works on both GLP-1 and GIP receptors. Because of this dual action, it is often described as a GIP/GLP-1 medication.
Neither drug was designed to increase testosterone. Their main jobs are controlling blood glucose and, depending on the product and indication, helping people lose weight.
But weight loss can change male hormones.
As abdominal fat decreases, the body may convert less testosterone into estradiol. Insulin sensitivity improves. SHBG may rise. Inflammation may settle down. Some men sleep better and become more physically active. Blood pressure, cholesterol, and glucose control may improve too.
All of that creates a healthier environment for testosterone production.
What the research says about testosterone
Several studies now suggest that GLP-1 medications can increase testosterone in men with obesity-related hormonal problems.
A recent systematic review found that GLP-1 receptor agonists were associated with higher total testosterone, especially in men with obesity, type 2 diabetes, or functional hypogonadism. The findings were generally positive, although the included studies were small and varied considerably in design. The review is available through PubMed.
Another meta-analysis found an increase in bioavailable testosterone but less certain results for free testosterone and SHBG. This matters because “testosterone” is not a single, simple measurement.
Total testosterone represents the testosterone circulating in different forms in the blood. Some is tightly bound to SHBG, some is loosely attached to albumin, and a small portion circulates freely. Obesity can change these carrier proteins, making laboratory results harder to interpret.
A man may see his total testosterone rise partly because weight loss restores SHBG. That is still a meaningful metabolic change, but it does not necessarily mean his testicles suddenly doubled their testosterone output.
One small clinical study followed men with obesity, type 2 diabetes, and functional hypogonadism who received semaglutide for 24 weeks. Testosterone levels and symptoms of hypogonadism improved. The men also experienced changes in body composition and sperm morphology. The study was published in Diabetes, Obesity and Metabolism.
Research involving liraglutide, an older GLP-1 medication, has reported similar patterns. In men with obesity-related low testosterone, treatment was associated with increases in total testosterone, LH, and FSH.
The rise in LH and FSH is particularly interesting. These are the signals the brain and pituitary gland use to stimulate the testicles. Their improvement suggests that weight loss treatment may help restore the body’s own reproductive hormone system rather than merely increasing a number on a laboratory report.
At the Endocrine Society’s 2026 annual meeting, researchers presented a review of five randomized clinical trials examining GLP-1 medications, reproductive hormones, and semen quality. They concluded that these drugs did not appear to suppress the male hormonal axis and might improve testosterone and sperm parameters in men with obesity-related hypogonadism.
They also offered an essential warning: the evidence remains limited and inconsistent. The trials used different medications, included different types of patients, and measured different outcomes. Larger studies are still needed. The Endocrine Society summarized the research.
In plain language, the hormonal signal looks promising. It is not yet strong enough to treat Ozempic or Mounjaro as testosterone medications.
Is the drug raising testosterone, or is the weight loss doing it?
Probably both are possible, but weight loss appears to explain much of the effect.
Scientists already knew that losing excess weight could raise testosterone long before semaglutide became famous. Lifestyle changes and bariatric surgery have both produced hormonal improvements in men with obesity.
The larger the weight loss, the greater the potential recovery tends to be.
When abdominal fat decreases, aromatase activity may decline. Insulin sensitivity improves, inflammatory pressure drops, and SHBG may recover. Sleep apnea can become less severe. Men often become more active, which helps preserve muscle and supports better metabolic health.
GLP-1 medications make meaningful, sustained weight loss possible for people who previously struggled to achieve it. In that sense, the medication may be the tool that allows the hormonal recovery to happen.
Could there be a direct effect on the reproductive system?
Possibly. Researchers have identified GLP-1 receptors in male reproductive tissues and have explored direct effects on testicular cells and sperm in laboratory and animal studies. Proposed benefits include better cellular energy use and lower oxidative stress.
Human evidence for a direct effect is not strong enough to make firm claims. A man taking semaglutide may lose weight, improve his diabetes, become more active, sleep better, and change his diet at the same time. It is difficult to isolate one mechanism from all the others.
For now, it is safest to say that improved metabolic health is probably the main driver. A separate effect on reproductive tissue remains possible but unproven.
Can Ozempic improve sperm quality?
This is where the story becomes both exciting and easy to exaggerate.
In the 24-week semaglutide study, men experienced an improvement in sperm morphology—the percentage of sperm with a normal shape and structure.
Morphology matters because unusually shaped sperm may have greater difficulty moving efficiently or fertilizing an egg. But morphology is only one part of a semen analysis.
Doctors may also examine:
- Semen volume
- Sperm concentration
- Total sperm count
- Motility
- Progressive motility
- Vitality
A man can improve in one category without improving in another. Better morphology does not automatically mean that conception will occur.
The semaglutide study was also small and involved a very particular group: men with obesity, type 2 diabetes, and functional hypogonadism. Its results cannot automatically be applied to every man taking Ozempic.
Other studies involving liraglutide have reported improvements in sperm concentration and total sperm count. Research on weight loss more generally has also found that men who lose excess weight may improve certain semen parameters, particularly when they keep the weight off.
There are good biological reasons for this.
Obesity is associated with increased scrotal temperature, inflammation, oxidative stress, hormonal disruption, and poorer glucose control. These conditions may interfere with sperm development. Improving metabolic health could reduce some of that pressure.
Sperm do not develop overnight. The full process takes roughly two and a half to three months. Any genuine change in sperm quality would therefore be expected to appear gradually, not a week after the first injection.
Even then, a healthier semen analysis does not prove that a medication increases fertility in the real-world sense.
A couple’s chance of pregnancy depends on both partners, their ages, timing of intercourse, ovulation, fallopian tube health, sperm DNA quality, and many other factors. Researchers have not yet demonstrated that men taking semaglutide produce more pregnancies or live births.
The careful answer is that Ozempic may improve certain sperm measurements in metabolically unhealthy men. Calling it a proven male fertility treatment would be premature.
What about Mounjaro and sperm?
Direct human evidence for tirzepatide and male fertility is much thinner.
Mounjaro can produce substantial weight loss and significant improvements in glucose control. It may therefore help men whose testosterone and sperm health have been affected by obesity or diabetes. That idea makes biological sense, but much of it is still an inference.
Animal fertility studies submitted to the FDA found no harmful effects on sperm morphology, mating, fertility, or conception in male rats given tirzepatide at the tested doses. This is reassuring, but animal studies cannot tell us exactly what will happen in humans. The findings appear in the FDA prescribing information for tirzepatide.
There is currently no convincing evidence that prescribed Mounjaro damages male fertility. There is also no convincing evidence that it makes a man more fertile.
It may help indirectly by treating the conditions interfering with reproductive function. Until larger human studies measure sperm quality and pregnancy outcomes, stronger claims are not justified.
Higher testosterone does not always mean better fertility
This sounds contradictory, but it is one of the most important facts in male reproductive medicine.
The testicles need high local concentrations of testosterone to produce sperm. Yet taking testosterone from outside the body can sharply reduce sperm production.
When a man uses testosterone injections, gels, or pellets, the brain senses that enough hormone is present in the blood. It responds by reducing LH and FSH. Without those signals, the testicles produce less of their own testosterone, and sperm production may slow dramatically or stop.
A man can therefore have an excellent testosterone result on paper and very few sperm in his semen.
This is why testosterone replacement therapy is generally unsuitable for men actively trying to conceive unless a reproductive specialist is managing the situation.
GLP-1 medications appear to behave differently. Rather than replacing testosterone, they may reduce the metabolic conditions suppressing natural hormone production. The brain and testicles continue communicating, and LH and FSH are not switched off in the way they can be during testosterone therapy.
That makes these medications scientifically interesting for men with obesity-related low testosterone who want children.
It does not mean a man should replace testosterone with Ozempic without medical supervision. Stopping testosterone suddenly can cause fatigue, low mood, loss of libido, and other difficult symptoms. Recovery of sperm production can take months and occasionally longer.
A reproductive urologist or endocrinologist can investigate why testosterone is low and discuss options that better protect fertility. The correct treatment depends on the cause, not simply the testosterone number.
Could these drugs improve erections and libido?
They might, although the effect is usually indirect.
Obesity and type 2 diabetes are major risk factors for erectile dysfunction. They can damage blood vessels, impair nerve function, reduce nitric oxide activity, and contribute to low testosterone.
A man who loses 40 pounds and brings his glucose under better control may experience stronger erections because his circulation and metabolic health have improved. He may also feel more confident and comfortable during sex.
If his testosterone was genuinely low, a return toward a healthier range could improve sexual desire. Better sleep and increased energy may help too.
But Ozempic and Mounjaro are not erectile dysfunction medications. A man should not expect an injection intended for diabetes or obesity to work like sildenafil or tadalafil.
ED can also be an early warning sign of cardiovascular disease. Men whose erections remain unreliable should not assume that losing more weight is the only answer. A medical assessment may uncover high blood pressure, diabetes, abnormal cholesterol, medication effects, or another condition requiring treatment.
When erection quality remains the primary concern, established erectile dysfunction treatments can be discussed with a qualified healthcare professional.
Some patients actually notice lower sexual interest after starting a GLP-1 medication. Nausea, fatigue, extreme calorie restriction, dehydration, and rapid muscle loss can make sex less appealing. Changes in mood or relationship dynamics may also play a role.
A medication can improve testosterone while a man still feels too sick or underfed to enjoy sex. Hormones are only one part of the picture.
Which men are most likely to benefit?
The strongest case involves a man whose hormonal problems are closely linked to obesity.
He may have excess abdominal fat, insulin resistance, type 2 diabetes, sleep apnea, low energy, reduced libido, and repeatedly low morning testosterone. His LH and FSH may be low or inappropriately normal rather than strongly elevated.
This pattern suggests that the hormonal system is being suppressed rather than that the testicles have completely failed.
Meaningful weight loss may help restore function.
The same result should not be expected in every cause of low testosterone or infertility. Ozempic and Mounjaro cannot repair a blocked reproductive tract, a significant varicocele, chromosome abnormality, pituitary tumor, prior testicular injury, or damage caused by chemotherapy.
They are also unlikely to increase testosterone meaningfully in a lean, healthy man whose levels are already normal. Testosterone is a regulated hormone, not a performance score that should be pushed as high as possible.
Imagine two men with the same low total testosterone result.
The first has obesity, prediabetes, and severe sleep apnea. The second is lean but previously underwent testicular surgery and has very high FSH. Their laboratory numbers may look similar, but the cause is entirely different.
Treating metabolic disease might substantially help the first man. It would not be expected to reverse the second man’s testicular damage.
What the studies still cannot tell us
The most enthusiastic headlines make the research sound more settled than it is.
Most available trials have included relatively few men. Some lasted only 16 or 24 weeks. Many participants had several overlapping conditions, including obesity, diabetes, and low testosterone.
Different studies used different GLP-1 medications and measured different hormones or semen parameters. Some focused on testosterone; others looked at sperm count, morphology, or body composition.
Semen results naturally fluctuate as well. Fever, illness, stress, abstinence time, sample collection, and laboratory methods can all affect the result. One unusually good or bad analysis may not reflect a man’s usual fertility.
Most critically, we do not yet know whether the laboratory improvements lead to more natural conceptions, more successful fertility treatments, fewer miscarriages, or more live births.
Researchers also need to determine:
- Whether benefits continue during long-term treatment
- What happens after the medication is stopped
- Whether testosterone falls again after weight regain
- Whether semaglutide and tirzepatide have similar reproductive effects
- Whether the drugs help independently of weight loss
- Which patients are most likely to respond
- Whether very rapid weight loss has different effects from gradual weight loss
Until those questions are answered, the medications should be viewed as promising metabolic treatments with possible reproductive benefits—not established fertility therapies.
Can rapid weight loss cause problems of its own?
Losing excess fat generally improves male health, but doing it poorly can create new problems.
GLP-1 medications may reduce appetite so effectively that some patients struggle to eat enough protein or maintain a balanced diet. A man may lose weight quickly while also losing muscle, strength, and energy.
If he is surviving on coffee, crackers, and a protein bar because every proper meal makes him nauseated, the falling number on the scale is not the whole story.
Severe calorie restriction can itself interfere with reproductive hormones. Nutritional deficiencies may develop, especially when vomiting, diarrhea, or extremely limited food intake continues. Loss of muscle may also reduce some of the metabolic benefits the patient hoped to gain.
Resistance exercise and adequate nutrition can help preserve lean mass. Protein needs should be individualized, particularly for people with kidney disease or other medical conditions.
Persistent vomiting, severe abdominal pain, dehydration, or an inability to eat should be reported to the prescriber. These are not signs that a medication is “working better.”
There is no strong evidence that medically supervised weight loss with Ozempic or Mounjaro causes male infertility. The greater concern is poorly managed treatment, extreme restriction, or the use of questionable products purchased without proper medical care.
Safety should not disappear from the conversation
A possible testosterone benefit does not erase the established risks of these medications.
Common side effects include nausea, vomiting, diarrhea, constipation, abdominal discomfort, and reduced appetite. More serious problems may include pancreatitis, gallbladder disease, dehydration-related kidney injury, and severe gastrointestinal reactions.
Hypoglycemia can occur, particularly when semaglutide or tirzepatide is used with insulin or certain other diabetes medications.
Both medications carry boxed warnings related to thyroid C-cell tumors observed in rodents. They are generally contraindicated in people with a personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia syndrome type 2.
Treatment also requires extra care in patients with diabetic retinopathy, significant gastrointestinal disease, kidney problems, or a history of pancreatitis.
Another concern is the growing market for counterfeit, improperly compounded, or unapproved GLP-1 products. The FDA has received reports of dosing errors and has warned consumers about products sold online with unclear ingredients or misleading claims.
Compounded drugs are not reviewed through the same approval process for safety, effectiveness, and manufacturing quality as FDA-approved medications. The FDA explains its concerns about unapproved GLP-1 products.
Men worried about fertility should be especially cautious about combining GLP-1 drugs with anabolic steroids, testosterone boosters, “research peptides,” or unregulated supplements. The mixture can make symptoms and laboratory results extremely difficult to interpret.
Should men stop Ozempic or Mounjaro before trying for a baby?
There is currently no universal rule requiring every man to stop semaglutide or tirzepatide before conception.
Most warnings about pregnancy concern women taking these medications during pregnancy. Paternal exposure is different because a medication taken by the father does not expose an embryo in the same way as a drug circulating in a pregnant woman’s body.
Available evidence has not shown that men must routinely discontinue prescribed Ozempic or Mounjaro before trying to conceive. Human data are still limited, so the decision should be made individually.
Why is the man taking the drug? How well controlled is his diabetes? Has he experienced nutritional problems? Are his semen results abnormal? Would stopping treatment lead to rapid weight regain or worsening glucose control?
Poorly controlled diabetes can damage sexual and reproductive health. Stopping treatment without a medical plan may create more risk than continuing it.
A man preparing for conception should tell his prescriber and fertility specialist about every medication and supplement he uses. He should not stop diabetes medication, testosterone, or another hormonal treatment abruptly without guidance.
What testing is useful?
A testosterone test cannot tell a man whether he is fertile.
A proper evaluation usually includes a reproductive history, medical history, physical examination, and semen analysis. Doctors may ask about previous pregnancies, childhood testicular problems, infections, surgery, cancer treatment, anabolic steroid use, smoking, alcohol, heat exposure, and sexual function.
When hormone testing is appropriate, it may include morning total testosterone, LH, FSH, prolactin, SHBG, and sometimes free testosterone or estradiol.
Low testosterone should usually be confirmed rather than diagnosed from a single afternoon blood test. Testosterone levels naturally change throughout the day and can temporarily fall during illness, poor sleep, or severe calorie restriction.
Semen analysis remains central when fertility is the concern. Because the results can vary, an abnormal test may need to be repeated.
A man already using Ozempic or Mounjaro could discuss whether baseline and follow-up testing would be useful. Randomly checking hormones every few weeks usually creates more confusion than clarity. Changes need to be interpreted alongside symptoms, weight loss, glucose control, medications, and reproductive goals.
What men can realistically expect
Ozempic or Mounjaro is not likely to produce an overnight testosterone surge.
If testosterone improves, the change will probably happen gradually as metabolic health improves. The same is true for sperm. Because sperm development takes months, any meaningful change in semen quality requires patience.
Some men may notice better energy, erections, or libido before their laboratory results change significantly. Those improvements may come from better sleep, more confidence, improved glucose control, or easier physical movement rather than testosterone alone.
Other men may lose substantial weight and still have low testosterone because obesity was not the only cause. Some will experience no reproductive improvement.
This is why individual stories online can be misleading. A man may credit Mounjaro when his partner becomes pregnant, but that does not prove the medication caused the pregnancy. Another may blame Ozempic for lower libido when he is eating too little, sleeping poorly, or experiencing relationship stress.
Personal experiences matter, but they cannot replace controlled research.
What to discuss with your doctor
A useful appointment goes beyond asking, “Will Ozempic boost my testosterone?”
Better questions include:
- Could my weight, diabetes, or sleep apnea be suppressing testosterone?
- Was my low result confirmed with a second morning test?
- Should LH, FSH, SHBG, or prolactin be checked?
- Do I need a semen analysis?
- How can I preserve muscle and nutrition while losing weight?
- When should my hormones or semen quality be reassessed?
- Could any of my medications be reducing fertility?
- Should I see a reproductive urologist?
- What should I do if gastrointestinal side effects prevent me from eating properly?
Men using testosterone or anabolic steroids need to tell the doctor. Hiding hormone use makes reproductive test results almost impossible to interpret correctly.
Couples are often advised to seek a fertility evaluation after 12 months of regular unprotected intercourse when the female partner is younger than 35, or after six months when she is 35 or older. Earlier testing may be appropriate when either partner already has a known risk factor.
The male evaluation should not be treated as an afterthought. A semen analysis is relatively simple, and male factors contribute to many cases of infertility.
Can Ozempic and Mounjaro really improve male fertility?
They may improve the conditions that allow normal male reproductive function.
Semaglutide has been associated with higher testosterone and better sperm morphology in a small study involving men with obesity, diabetes, and functional hypogonadism. Research involving liraglutide has reported improvements in testosterone and selected sperm measurements.
For Mounjaro, the argument is more indirect. Tirzepatide produces powerful metabolic changes, but direct human research on sperm quality and pregnancy outcomes remains limited.
The potential benefit appears greatest in men whose reproductive problems are linked to obesity and insulin resistance. By reducing abdominal fat and improving metabolic health, these medications may help the brain and testicles communicate more normally.
That is genuinely promising.
But higher testosterone is not the same as proven fertility, and improved sperm morphology is not the same as a successful pregnancy. Neither Ozempic nor Mounjaro is FDA-approved to treat low testosterone or male infertility.
For the right patient, a reproductive benefit may become one more positive consequence of treating obesity or diabetes. For everyone else, the claim remains ahead of the science.
