Does Mounjaro Affect Fertility — and What Should You Do Before Trying to Conceive?

What the current evidence actually tells us about tirzepatide and fertility

The honest answer is that robust human fertility data for tirzepatide does not yet exist. The SURMOUNT clinical programme involved thousands of adults, but participants were required to use effective contraception throughout, so direct data on conception rates was deliberately excluded. What researchers have from animal studies suggests potential embryo toxicity at high doses, which is why the precautionary guidance is so clear: stop treatment, allow a wash-out period, and speak to a clinician before trying to conceive.

For women, the more clinically significant picture is indirect. Conditions like polycystic ovary syndrome (PCOS) and obesity-related hormonal dysregulation are among the most common drivers of ovulatory difficulty, and meaningful weight loss can restore more regular cycles and improve ovulatory function, even before reaching a 'normal' BMI. Whether this reflects a direct mechanism of tirzepatide or simply the downstream effect of significant weight reduction is still being studied. Our page on how Mounjaro may affect fertility in women explores the hormonal picture in more detail.

For men, evidence is even thinner. There is no clinical data showing that tirzepatide impairs sperm quality, count or motility in humans. The question of Mounjaro and male fertility is genuinely an open one, animal reproductive toxicology data informs the caution, not confirmed human outcomes. If you are trying to conceive as a male partner, raise it with your prescriber; the guidance does not currently recommend stopping treatment in men, but the conversation is worth having. You can read more about the overall evidence on tirzepatide's effect on fertility in our dedicated resource.

The contraception question: why this matters more than most people realise

One thing the evidence is clear on: tirzepatide slows gastric emptying, which can reduce how well oral contraceptives are absorbed. The NHS England guidance on weight-management injections advises that women taking the pill should add a non-oral contraceptive method (condoms being the most practical) for the first four weeks of Mounjaro treatment and for four weeks after every dose increase.

This is not a small footnote. If you are using oral contraception specifically to avoid pregnancy while you lose weight, the timing of your dose increases matters. Many people plan starts around work schedules or commitments, but if you are titrating up to 5mg or 7.5mg, factor in a month of additional contraception at each step. A prescriber can help you plan this in a way that fits your actual life.

For women who are not using contraception because they believe they are unlikely to conceive, it is worth discussing this assumption explicitly. Weight loss can improve fertility unexpectedly, particularly in women with PCOS or irregular cycles who may previously have struggled to conceive. Our Mounjaro and fertility overview covers this scenario specifically.

If you are thinking about stopping Mounjaro to try for a baby

This is a decision that benefits from a proper conversation rather than an independent one. The MHRA advises a wash-out period before attempting conception; the exact recommended duration is stated in the Patient Information Leaflet and should be confirmed with your prescriber, because it may change as post-marketing data accumulates. Do not simply stop injections without guidance on timing, both the stopping process and what to do about ongoing weight management during a pregnancy attempt need planning.

Some women who have lost significant weight on tirzepatide find that their BMI, blood pressure or metabolic profile has improved enough to change the clinical picture around conception entirely. That is a meaningful outcome. Others may want to pause treatment, conceive, deliver, stop breastfeeding, and then return to treatment. All of these are routes a prescriber can help map out. There is also useful context on whether Mounjaro can help with fertility (specifically in cases of obesity-related ovulatory dysfunction) if that is the direction of your thinking.

If you are already taking Mounjaro and have questions about your current plan, our free consultation is the right starting point, a GPhC-registered prescriber reads your answers the same day and can advise on exactly this kind of situation.

What to bring to your prescriber (or GP) when this is your situation

Fertility-related queries are among the ones our prescribers take most seriously, because the stakes are real and the evidence is still developing. A useful conversation covers: your current contraception method and whether it is likely to remain effective alongside tirzepatide; your timeline for trying to conceive; any underlying conditions (PCOS, endometriosis, thyroid issues) that might interact with both weight loss and reproductive function; and your partner's situation if relevant.

If you are under active care with a fertility specialist or gynaecologist, share your Mounjaro prescription with them. This is not a situation to manage in silos. The NHS medicines information for tirzepatide covers the key contraindications and precautions in plain language; reading it alongside a specialist conversation is a reasonable starting point.

For a broader look at what treatment through a regulated UK pharmacy involves, our Mounjaro overview explains the licensed indication, the clinical assessment process, and how ongoing aftercare works. Check your eligibility through our free consultation, it takes a few minutes, and a prescriber reviews it properly the same day.