The short answer is different for men and women.
Current EU product information tells a woman who may become pregnant to stop semaglutide, meaning Ozempic or Wegovy, at least 2 months before a planned pregnancy. It tells her to stop tirzepatide, meaning Mounjaro, at least 1 month before a planned pregnancy.
Those washout periods are not instructions for a male partner who is trying to father a pregnancy. Current European Medicines Agency product information does not specify a preconception washout period for men taking Ozempic, Wegovy or Mounjaro.
That does not mean male fertility has been proved unaffected. It means the evidence and the question are different.
Short answer
For a man taking Ozempic, Wegovy or Mounjaro while trying to conceive with a partner who can become pregnant:
- current EU product information does not tell men to stop for 1 or 2 months before conception
- no increased birth-defect risk from paternal semaglutide or tirzepatide exposure has been established, but direct human pregnancy-outcome data on exposed fathers are very limited
- the effect of semaglutide or tirzepatide on human fertility is officially described as unknown
- small human studies, mainly involving semaglutide or liraglutide rather than tirzepatide, suggest that GLP-1-based treatment and sustained weight loss may improve some hormone or semen measures in men with obesity, type 2 diabetes or functional hypogonadism
- those studies do not prove that the medicines improve the chance of pregnancy or live birth
- do not stop diabetes treatment or change dose without a replacement plan from the clinician managing it
If you already have abnormal semen results, known infertility, very rapid weight loss, persistent vomiting or poor food intake, discuss the plan before continuing unchanged.
If you are the person who may become pregnant, read our separate guide to Ozempic, Wegovy, Mounjaro and pregnancy planning.
The common mistake: applying the pregnancy washout period to the man
Online advice often repeats the 2-month semaglutide washout or 1-month tirzepatide washout without stating who it applies to.
The EU pregnancy instructions concern the person who may become pregnant and whose medicine can directly expose the pregnancy through her bloodstream. A male partner does not share a blood connection with the pregnancy. In general, medicines in a father's bloodstream do not directly reach the fetus. Small amounts of some substances can enter semen, but paternal exposures are usually considered unlikely to increase pregnancy risk unless a specific medicine has evidence or instructions to the contrary.
For Ozempic, Wegovy and Mounjaro, current EMA product information contains no male contraception rule and no paternal washout interval.
Do not convert missing data into a made-up male washout period. If a fertility clinic gives you a specific instruction for an assisted-reproduction procedure, follow that clinic's protocol.
What current EU product information actually says about male fertility
Ozempic and Wegovy
Both contain semaglutide. Current EMA product information says the effect of semaglutide on fertility in humans is unknown. It also says semaglutide did not affect mating performance or male fertility in rat studies.
Rat data cannot prove safety or fertility benefit in men. They are reassuring preclinical information, not a human conception study.
Mounjaro
Mounjaro contains tirzepatide. Current EMA product information says its effect on fertility in humans is unknown. It says animal studies did not indicate direct harmful effects with respect to fertility.
Again, that is not the same as having large studies of men who conceived children while taking tirzepatide. Human semen and paternal pregnancy-outcome data for tirzepatide remain especially sparse.
Could these medicines affect sperm?
Possibly, but the direction is not established for every man.
Obesity, type 2 diabetes and functional hypogonadism can themselves be associated with lower testosterone and poorer semen parameters. Improving weight and metabolic health may therefore help some men. A medicine could also have effects that are not explained by weight loss alone. Current studies are too small and mixed to separate those pathways confidently.
The most direct semaglutide study is encouraging but small
Gregorič and colleagues reported a 24-week randomized open-label trial in 25 men with obesity, type 2 diabetes and functional hypogonadism. The men received semaglutide 1 mg weekly or testosterone replacement therapy.
In the semaglutide group, the median proportion of sperm with normal shape increased from 2% to 4%. Total testosterone and symptoms of hypogonadism also improved. Sperm concentration and total sperm number were better preserved than in the testosterone group.
This is useful evidence, but it has important limits:
- only 25 men were enrolled
- participants already had obesity, diabetes, hypogonadism and poor baseline semen parameters
- the trial was open-label
- it compared semaglutide with testosterone treatment, which can suppress sperm production
- it measured semen and hormone markers, not pregnancies, miscarriages, birth defects or live births
- the dose studied was semaglutide 1 mg weekly, not every possible Ozempic or Wegovy dose
Because testosterone treatment is itself potentially sperm-suppressive, the comparison is useful clinically but does not prove that semaglutide would outperform placebo or lifestyle treatment for fertility outcomes.
The result should not be translated into "semaglutide boosts male fertility." It suggests no obvious semen-harm signal in this small selected group and a possible improvement in sperm morphology.
Weight loss itself may matter
Andersen and colleagues studied 56 men with obesity. After an 8-week low-calorie diet, average weight loss was 16.5 kg. Sperm concentration increased 1.49-fold and total sperm count increased 1.41-fold. Improvements were maintained over the following year in men who maintained weight loss. The maintenance strategies included exercise, liraglutide 3 mg, both, or placebo; this was not a semaglutide or tirzepatide trial.
This supports a broader point: sustained metabolic improvement may help semen quality in some men with obesity. It does not isolate a direct fertility effect of semaglutide or tirzepatide, and it did not show that GLP-1 treatment increases pregnancy or live-birth rates.
A 2026 systematic review of 10 studies involving 639 men found that GLP-1 receptor agonists were associated with higher total testosterone and possible improvements in semen measures mainly among men with obesity, diabetes or functional hypogonadism. The authors still judged the evidence insufficient for firm conclusions and called for larger, longer controlled studies.
Could the father's use harm the baby?
There is no established evidence that a father's use of semaglutide or tirzepatide increases the risk of birth defects.
However, the honest wording is not "proved safe." Direct studies following pregnancies fathered by men using these medicines are lacking. Existing evidence mainly addresses animal fertility, male hormones, semen measures and the general biology of paternal exposure.
For most medicines, paternal exposure is less concerning for fetal drug exposure than maternal use because the father's bloodstream does not supply the pregnancy. The main plausible paternal question is whether a medicine changes fertility or sperm, not whether his weekly injection directly reaches the fetus.
This is why the 1-month or 2-month washout instruction for the person who may become pregnant should not automatically be imposed on the man.
When a man should request an individual review
Arrange a medication review, and involve a fertility clinician where relevant, if:
- you already have an abnormal semen analysis or diagnosed infertility
- you and your partner are planning IVF, ICSI or another assisted-reproduction procedure
- you have testicular disease, previous chemotherapy, pelvic surgery or another established fertility risk
- you are also using testosterone or anabolic steroids
- nausea, vomiting or appetite suppression makes it difficult to eat adequately
- weight loss is very rapid or you feel weak, unwell or nutritionally depleted
- sexual function or libido has worsened
- you take Ozempic or Mounjaro for type 2 diabetes and are considering stopping
Do not replace a GLP-1 medicine with testosterone simply because testosterone is low when conception is a goal. External testosterone can suppress the hormonal signals needed for sperm production. This needs fertility-aware medical management.
A practical preconception plan for men
A sensible review should answer five questions:
- Why are you taking the medicine: type 2 diabetes, weight management or both?
- Is weight and glucose control improving without excessive nausea, vomiting or undernutrition?
- Is there an existing reason to suspect male-factor infertility?
- Is your partner already under fertility care or facing a time-sensitive fertility issue?
- Would changing treatment improve the overall plan, or would it destabilize diabetes and weight without evidence of reproductive benefit?
For most men without a fertility problem, current evidence does not support inventing a routine male washout period. For a man with infertility or an assisted-reproduction plan, individual review is more useful than generic internet advice.
Frequently asked questions
Does a man need to stop Ozempic or Wegovy 2 months before trying for a baby?
Current EU product information does not specify a 2-month preconception washout for men. The 2-month instruction applies to the patient who may become pregnant. Human data on male fertility and paternal pregnancy outcomes remain limited, so men with known infertility or fertility-treatment plans should seek individual advice.
Does a man need to stop Mounjaro 1 month before trying for a baby?
Current EU product information does not specify a 1-month paternal washout period. The 1-month instruction concerns the patient planning to become pregnant. Tirzepatide's effect on human fertility is unknown, and direct human male data are sparse.
Can semaglutide improve sperm count or testosterone?
Small studies in men with obesity, diabetes or functional hypogonadism report improvements in testosterone and some semen measures. This may partly reflect weight loss and improved metabolic health. It has not been proved to improve pregnancy or live-birth rates.
Can Mounjaro damage sperm?
There is not enough direct human evidence to say that tirzepatide improves or damages sperm. EMA product information reports no direct harmful fertility effect in animal studies, but human fertility is described as unknown.
Can a father's Ozempic, Wegovy or Mounjaro exposure cause birth defects?
No increased birth-defect risk from paternal exposure has been established. Direct pregnancy-outcome studies in exposed fathers are lacking. General teratology guidance considers most paternal medicine exposures unlikely to increase pregnancy risk because the father's bloodstream does not directly expose the fetus.
The bottom line
Men and women should not be given the same preconception instruction automatically.
For the person who may become pregnant, current EU product information gives clear semaglutide and tirzepatide stop intervals. For men trying to father a pregnancy, it gives no routine washout period. Human male-fertility evidence is still limited. The available semaglutide and liraglutide data are more reassuring than alarming, but direct tirzepatide data in men trying to conceive remain very sparse.
Do not stop Ozempic, Wegovy or Mounjaro solely because your partner wants to become pregnant without first reviewing why you take it and what would replace it. If infertility, abnormal semen results or assisted reproduction are already part of the picture, involve the fertility clinician as well.
If you want a physician to review medication, weight maintenance, nutrition and metabolic health before conception, request a medication and weight-maintenance review at Élan Clinic.
Élan Clinic does not replace a fertility clinic, semen laboratory or reproductive-medicine specialist. This article provides general education and does not replace individual medical advice.
Sources and funding context
- European Medicines Agency. Ozempic: EPAR product information. Current EU regulatory product information, accessed 2026-07-20. Used for exact fertility, pregnancy and preclinical wording. Regulatory product information, not a journal study. https://www.ema.europa.eu/en/documents/product-information/ozempic-epar-product-information_en.pdf
- European Medicines Agency. Wegovy: EPAR product information. Current EU regulatory product information, accessed 2026-07-20. Used for exact fertility, pregnancy and preclinical wording. Regulatory product information, not a journal study. https://www.ema.europa.eu/en/documents/product-information/wegovy-epar-product-information_en.pdf
- European Medicines Agency. Mounjaro: EPAR product information. Current EU regulatory product information, accessed 2026-07-20. Used for exact fertility, pregnancy and preclinical wording. Regulatory product information, not a journal study. https://www.ema.europa.eu/en/documents/product-information/mounjaro-epar-product-information_en.pdf
- Gregorič N, Šikonja J, Janež A, Jensterle M. Semaglutide improved sperm morphology in obese men with type 2 diabetes mellitus and functional hypogonadism. Diabetes, Obesity and Metabolism. 2025;27(2):519-528. Randomized open-label trial, n=25, 24 weeks. DOI: 10.1111/dom.16042. PMID: 39511836. Supported by Slovenian Research Agency grants; pharmaceutical companies were not involved in funding or authorship. Several authors reported lecture, consulting or advisory relationships with pharmaceutical companies.
- Andersen E, Juhl CR, Kjøller ET, et al. Sperm count is increased by diet-induced weight loss and maintained by exercise or GLP-1 analogue treatment: a randomized controlled trial. Human Reproduction. 2022;37(7):1414-1422. Semen substudy, n=56. DOI: 10.1093/humrep/deac096. PMID: 35580859. Supported partly by Novo Nordisk Foundation grants; liraglutide and placebo pens were supplied by Novo Nordisk. Author conflicts are reported in the paper.
- Ghassab Deameh M, Ramez M, Rowaiee R, et al. Effects of glucagon-like peptide-1 receptor agonists on male reproductive hormones, semen parameters, and metabolic outcomes: a systematic review. Journal of Sexual Medicine. 2026;23(2):qdaf381. Ten studies, n=639 men. DOI: 10.1093/jsxmed/qdaf381. PMID: 41498523. The PubMed record did not list funding or a conflict-of-interest statement; the full article was not openly accessible in the sources checked.
- MotherToBaby. Semaglutide. Fact Sheet, NCBI Bookshelf. Used as supplementary teratology guidance on paternal exposure; its male-fertility section predates the 2025 semaglutide trial and should not be treated as a current systematic review. Accessed 2026-07-20. https://www.ncbi.nlm.nih.gov/books/NBK600385/
- MotherToBaby. Paternal Exposures. Fact Sheet, NCBI Bookshelf. Used for the general explanation of paternal bloodstream and semen exposure. Accessed 2026-07-20. https://www.ncbi.nlm.nih.gov/books/NBK582898/