Mounjaro isn't specifically licensed or clinically trialled for PCOS — Eli Lilly has confirmed it hasn't sponsored any studies evaluating tirzepatide specifically in people with PCOS. However, Mounjaro is licensed for weight management (BMI 30+, or 27–30 with a weight-related condition) and for type 2 diabetes, and many women with PCOS meet these standard eligibility criteria, particularly given how closely PCOS is linked with insulin resistance and weight gain. Small independent studies and case series have reported promising results when tirzepatide is used off-label in women with PCOS, including meaningful weight loss and improved insulin resistance, but this remains a developing evidence base rather than an established, licensed use.
It's important to start with clarity here. Mounjaro is licensed in the UK for weight management in adults meeting standard BMI criteria, and separately for improving blood sugar control in type 2 diabetes — see our dedicated Mounjaro and type 2 diabetes guide for that specific evidence base. It is not licensed specifically for PCOS, and Eli Lilly has been explicit that it hasn't sponsored clinical trials evaluating tirzepatide's safety or efficacy specifically in people with PCOS. Participants with PCOS weren't excluded from Mounjaro's diabetes trials (the SURPASS programme), but they made up a very small proportion — between 0.1% and 1.3% of participants across the five core trials — and no dedicated subgroup analysis was carried out.
What this means in practice
If you have PCOS and are considering Mounjaro, your eligibility will be assessed against the standard weight-management or diabetes criteria — not a PCOS-specific pathway, because no such pathway currently exists. Many women with PCOS do qualify under these standard criteria, since PCOS is strongly associated with both excess weight and insulin resistance, but it's worth understanding that you're accessing Mounjaro through its licensed uses, with any PCOS-related benefit arising indirectly. If you do start treatment, the same standard Mounjaro dose schedule applies, regardless of PCOS.
PCOS is genuinely common, affecting an estimated 5 to 10% of women of reproductive age, making it the most common endocrine condition in this group, and insulin resistance is present in a substantial majority of cases — documented in clamp studies in around 75% of women with PCOS. This creates a genuinely difficult cycle: insulin resistance contributes to weight gain, and excess weight in turn worsens insulin resistance and other PCOS symptoms, including irregular periods and elevated androgen levels. Breaking this cycle through weight loss is one of the most consistently recommended first-line approaches for managing PCOS, particularly in women who are overweight or living with obesity.
While there's no large, dedicated randomised trial of tirzepatide specifically for PCOS yet, smaller independent studies have started to build a picture of how it may perform in this population, used off-label.
A Retrospective Study of Women With PCOS
One retrospective observational study of 56 women with PCOS and obesity, referred for menstrual problems, obesity and hypertension, found an average weight reduction of 9.54% after tirzepatide treatment. Insulin resistance, present in 80.4% of participants at baseline, fell to 50% after treatment — a substantial and clinically meaningful improvement. The most commonly reported side effects were heartburn (42.9%), nausea and vomiting (39.3%), and general weakness (33.9%), broadly consistent with tirzepatide's known side-effect profile in its licensed uses.
Why Researchers Are Interested in Tirzepatide Specifically
Tirzepatide's dual GIP and GLP-1 mechanism has drawn particular research interest for PCOS, partly because its dual action may reduce the intensity of gastrointestinal side effects compared with single-mechanism GLP-1 medicines — a genuine practical consideration, since poor tolerability is a recognised reason people stop GLP-1 treatment. Researchers have also noted that weight loss of just 5% or more is associated with measurable improvements in insulin resistance, ovulatory function and cardiometabolic risk markers in women with PCOS, a threshold well within what Mounjaro has demonstrated in its licensed weight-management trials.
Important
This remains an evolving evidence base built on smaller studies and off-label use, not the same standard of evidence behind Mounjaro's licensed indications. Discuss the current state of evidence honestly with your prescriber, and treat promising early results as encouraging rather than definitive.
- Weight loss, which is the primary mechanism through which most PCOS-related benefits are thought to occur
- Improved insulin sensitivity, potentially reducing the long-term risk of type 2 diabetes that's elevated in PCOS
- Some studies and case reports suggest improved menstrual regularity as weight and insulin resistance improve, though this isn't guaranteed or specifically studied at scale
- Potential improvements in androgen-related symptoms (such as acne or excess hair growth) as metabolic markers improve, though again, this is an indirect effect via weight loss rather than a targeted mechanism
It's worth being realistic that Mounjaro doesn't treat PCOS directly — it isn't a hormonal therapy targeting the condition's reproductive features. Any benefit is understood to work through weight loss and improved insulin sensitivity, which happen to be central drivers of PCOS symptoms for many women.
Metformin has long been the standard insulin-sensitising treatment for PCOS, and it remains well-established with decades of research behind it. However, metformin's effect on weight loss specifically is often described in the research literature as modest and inconsistent, which is part of why interest in GLP-1 and dual-mechanism medicines like tirzepatide has grown. Some smaller studies suggest tirzepatide may outperform metformin for both weight loss and insulin resistance improvement in women with PCOS and obesity, though metformin's much longer track record and lower cost remain genuine advantages worth weighing.
A Combined Approach Often Works BestFor most women managing PCOS alongside excess weight, the most evidence-backed and realistic approach combines several elements rather than relying on medication alone: dietary changes (particularly reducing refined carbohydrates, which can worsen insulin resistance), regular physical activity, and medication where clinically appropriate. Mounjaro, where eligible, may be a genuinely useful part of this picture, particularly given the meaningful weight loss shown in its licensed trials — see our dedicated nutrition guide for dietary principles that support insulin sensitivity alongside GLP-1 treatment — but it works best as one part of a broader approach rather than a standalone fix for PCOS.
Fertility Considerations Worth KnowingIf you're managing PCOS and considering pregnancy in the near future, this is an important conversation to have before starting Mounjaro, not after. Mounjaro isn't recommended during pregnancy, and because PCOS itself is linked with fertility challenges, some women may find that improved insulin sensitivity and weight loss actually increase the chance of becoming pregnant while on treatment — which is exactly why reliable contraception is worth discussing with your prescriber if pregnancy isn't your current goal. If you are actively trying to conceive, this is worth raising openly during your consultation so your prescriber can advise on the right approach and timing.
Discuss Your Full Health Picture With Our Team
Our GPhC-registered pharmacy team can talk through your eligibility for Mounjaro, including how PCOS and related insulin resistance fit into your overall assessment.
Start Your Free Online Consultation → Happy Pharmacy is a GPhC-registered pharmacy (No. 9012585) — Superintendent Pharmacist: Palvinder Deol — Rated 4.8★ Excellent on Trustpilot- Weight loss outcomes with tirzepatide in women with and without self-reported polycystic ovary syndrome. Journal of the Endocrine Society, 2026.
- Role of Tirzepatide in Obesity Management Among Women with Polycystic Ovary Syndrome. Retrospective observational study.
- Has Mounjaro® (tirzepatide) been studied in patients with polycystic ovary syndrome (PCOS)? Eli Lilly and Company, medical.lilly.com.
- The Potential Utility of Tirzepatide for the Management of Polycystic Ovary Syndrome. PMC, National Institutes of Health.
- NHS. Polycystic ovary syndrome (PCOS): overview, symptoms and treatment.
- Mounjaro® (tirzepatide) UK Summary of Product Characteristics.