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Can Mounjaro Affect Fertility? Safety Profile Explained

Published on: June 03, 2026

Many UK patients ask can Mounjaro affect fertility UK before starting treatment. Mounjaro (tirzepatide) is not known to directly impair fertility, but weight loss itself can influence reproductive hormones and menstrual cycles. At Cured Pharmacy, our UK prescribers assess your complete medical history, including family planning intentions, during your free online consultation to ensure safe, informed treatment.

Does Mounjaro Directly Affect Fertility?

Mounjaro (tirzepatide) has not been shown to directly impair fertility in human studies. The medication works by activating GIP and GLP-1 receptors to regulate blood sugar and appetite, mechanisms that do not target reproductive organs or hormone production [1]. However, animal reproduction studies identified potential foetal risks, which is why tirzepatide is contraindicated during pregnancy in the UK.

What many patients experience is an indirect effect: significant weight loss can normalise ovulation in women with polycystic ovary syndrome (PCOS) or irregular cycles, potentially increasing fertility [2]. Conversely, rapid weight reduction may temporarily disrupt menstrual patterns in some individuals. Your UK prescriber will discuss these nuances based on your baseline BMI and reproductive health history.

Mounjaro and Pregnancy: What UK Guidelines Say

The MHRA advises discontinuing Mounjaro at least two months before a planned pregnancy due to its long half-life and potential foetal risk identified in animal studies [3]. If you become pregnant whilst taking tirzepatide, stop treatment immediately and inform your prescriber. There is insufficient human data to confirm safety during pregnancy, so a precautionary approach is essential.

Women of childbearing potential must use effective contraception throughout Mounjaro treatment and for at least two months after the final dose [3]. This requirement is clearly documented in the UK Summary of Product Characteristics and forms part of the clinical assessment at Cured Pharmacy.

Planning Pregnancy on Mounjaro

If you are planning to conceive, discuss a structured discontinuation plan with your UK prescriber. The two-month washout period allows tirzepatide to clear your system and gives you time to stabilise your weight through diet and lifestyle adjustments. Your prescriber may recommend transitioning to non-pharmacological weight management strategies during this window to maintain your progress.

Can Mounjaro Affect Fertility in Men?

Current evidence does not suggest tirzepatide impairs male fertility. The SURPASS clinical trial programme included male participants without reports of reproductive dysfunction [1]. However, obesity itself is associated with reduced testosterone levels, lower sperm quality, and erectile dysfunction in men.

Weight loss achieved through Mounjaro may improve these parameters. In clinical trials, patients on tirzepatide experienced average body weight reductions of up to 22.5% over 72 weeks, which can positively influence metabolic and hormonal profiles [1]. Men planning to father children can typically continue Mounjaro, but should discuss individual circumstances with their UK prescriber during the online consultation.

Contraception Requirements on Mounjaro

All women of childbearing age prescribed Mounjaro in the UK must use reliable contraception. Acceptable methods include combined oral contraceptives, intrauterine devices (IUDs), implants, or barrier methods combined with spermicide [3]. Your prescriber will confirm your contraceptive plan before approving treatment.

It is important to note that tirzepatide slows gastric emptying, which may theoretically reduce absorption of oral contraceptives, though this has not been conclusively demonstrated in clinical trials [4]. If you use oral contraceptives, consider discussing additional barrier methods or switching to a non-oral method with your GP or sexual health clinic.

Weight Loss, Hormones, and Reproductive Health

Significant weight loss can alter reproductive hormone levels, particularly in women with PCOS or hypothalamic amenorrhoea. As body fat decreases, oestrogen production from adipose tissue declines, which may temporarily disrupt menstrual regularity. Conversely, women with PCOS often see improved ovulation and cycle regularity as insulin resistance improves [2].

These changes underscore why contraception is essential even if you have previously struggled with fertility. Weight loss on Mounjaro may restore ovulatory cycles, increasing the chance of unplanned pregnancy if contraception is not used consistently.

Monitoring Menstrual Changes

Track your menstrual cycle throughout Mounjaro treatment. Report any significant changes—such as absent periods for three consecutive cycles or unusually heavy bleeding—to your prescriber. These may indicate hormonal shifts requiring further evaluation or dose adjustment.

Starting Mounjaro Safely at Cured Pharmacy

At Cured Pharmacy, all Mounjaro prescriptions begin with a free online consultation completed in under three minutes. Our UK-registered prescribers assess your medical history, current medications, family planning intentions, and contraception status to ensure tirzepatide is safe and appropriate for you. Mounjaro starts from £124.99, with transparent upfront pricing and discreet next-day delivery across the UK.

You will receive comprehensive guidance on injection technique, side effect management, and when to seek medical advice. Our superintendent pharmacist, Tarun Kumar (GPhC 2233073), oversees every prescription to ensure compliance with MHRA and GPhC standards. If you have questions about fertility or pregnancy planning, these can be addressed directly during your consultation or by contacting our clinical team on (+44) 116 4646009.

Alternative Weight Loss Treatments

If you are actively trying to conceive or cannot commit to reliable contraception, your prescriber may recommend alternative weight loss treatments. Options such as Orlistat work through a different mechanism (fat absorption inhibition) and do not carry the same pregnancy-related restrictions. Your UK prescriber will tailor recommendations to your individual circumstances and reproductive goals.

Scientific References

1. Jastreboff, A. M., et al. (2022). Tirzepatide Once Weekly for the Treatment of Obesity. New England Journal of Medicine, 387(3), 205–216. https://doi.org/10.1056/NEJMoa2206038 [accessed 13 August 2026]
2. Legro, R. S., et al. (2015). Effects of preconception lifestyle intervention in infertile women with obesity: The FIT-PLESE randomized controlled trial. Diabetes Care, 38(3), 356–363. https://doi.org/10.2337/dc14-2024 [accessed 13 August 2026]
3. Medicines and Healthcare products Regulatory Agency. (2023). Mounjaro 2.5 mg solution for injection in pre-filled pen: Summary of Product Characteristics. Electronic Medicines Compendium. Retrieved from https://www.medicines.org.uk/emc/product/14917 [accessed 13 August 2026]
4. Halberg, I. B., et al. (2019). Impact of oral semaglutide on the pharmacokinetics of lisinopril, warfarin, digoxin, and metformin in healthy subjects. Clinical Pharmacokinetics, 58(9), 1193–1203. https://doi.org/10.1007/s40262-019-00756-2 [accessed 13 August 2026]
5. NHS. (2026). Tirzepatide: a medicine to manage type 2 diabetes and treat obesity. https://www.nhs.uk/medicines/tirzepatide/ Accessed 13 August 2026.
6. NHS. (2026). Overweight and obesity in adults. https://www.nhs.uk/conditions/overweight-and-obesity/ Accessed 13 August 2026.
7. NHS England. (2026). Weight management injections. https://www.england.nhs.uk/ourwork/prevention/obesity/medicines-for-obesity/weight-management-injections/ Accessed 13 August 2026.

Information on this page is for educational purposes only and is not medical advice. All prescription treatments require clinical assessment by a UK-registered prescriber. Always consult a qualified healthcare professional before starting any new medication.