Living with PCOS? It can feel like your body's working against you. Weight gain that won't budge, irregular periods, insulin resistance — sometimes it seems like everything's conspiring to make progress impossible.

A lot of women with PCOS have tried restrictive diets, intensive workouts, and all sorts of plans, only to see minimal results. That frustration is real.

Mounjaro (tirzepatide) may help women with PCOS by improving insulin resistance, one of the condition's root causes, whilst also supporting weight loss and potentially restoring more regular ovulation. It is not specifically licensed for PCOS in the UK, but its dual-action mechanism makes it a promising option to discuss with your GP or prescriber.

We've dug into how Mounjaro actually works for PCOS, what benefits you might see, and what you should know before considering it. While it's not specifically licensed for PCOS in the UK, it's one of a newer generation of weight loss medications that may help with better ovulation rates in women with obesity and PCOS.

Key takeaways

Mounjaro addresses insulin resistance, a core issue in PCOS that affects weight, hormones, and fertility

The medication may improve ovulation and menstrual regularity whilst supporting significant weight loss. In clinical trials, people taking tirzepatide at the highest dose lost an average of 22.5% of their body weight over 72 weeks

Combining Mounjaro with lifestyle changes gives you the best shot at managing PCOS symptoms long-term

Mounjaro is not licensed specifically for PCOS in the UK, but its effects on insulin resistance make it a promising option to discuss with your GP or prescriber

Understanding PCOS and its key challenges

PCOS disrupts how your body processes insulin and produces hormones. This leads to symptoms that affect fertility, appearance, and long-term health.

The condition is more than just ovarian cysts. It creates a cycle of metabolic and hormonal problems that can feel overwhelming.

An infographic showing the PCOS cycle: insulin resistance leads to high insulin, which drives excess androgens, causing weight gain, irregular periods, and other symptoms, which in turn worsen insulin resistance.

What is polycystic ovary syndrome?

Polycystic ovary syndrome is an endocrine disorder (a condition that affects how your body produces and responds to hormones). It affects somewhere between 6% and 20% of women during their reproductive years.

Despite what the name suggests, not everyone with PCOS actually has cysts on their ovaries.

Doctors usually diagnose PCOS using the Rotterdam criteria, the internationally recognised standard for diagnosis. You need at least two of three conditions: irregular or absent periods (called anovulation, meaning your ovaries aren't releasing eggs regularly), signs of high androgen levels like excess hair growth or acne, and polycystic ovaries on an ultrasound.

PCOS doesn't look the same for everyone. Some women mainly struggle with irregular periods and infertility. Others notice visible symptoms like hirsutism (excess facial or body hair), acne, or androgenic alopecia (hair loss on the scalp).

PCOS isn't just a reproductive issue. It affects how your whole body handles metabolism and hormones. You can read more about the condition on the NHS PCOS overview page.

Insulin resistance in PCOS

Between 50% and 70% of women with PCOS deal with insulin resistance. Their cells don't respond properly to insulin, the hormone that moves glucose from blood into cells for energy.

When cells ignore insulin, the pancreas pumps out even more. These high insulin levels set off a chain reaction in the body.

This state of chronically elevated insulin is known medically as hyperinsulinemia. It goes beyond simple insulin resistance: your body is actively producing far more insulin than it should, and those excess levels directly drive many of the most frustrating PCOS symptoms.

High insulin nudges the ovaries to make excess androgens (male hormones), which worsens many PCOS symptoms. This causes hyperandrogenism (abnormally high levels of male hormones like testosterone), which brings on several visible symptoms:

Common androgenic symptoms:

Hirsutism (extra hair on your face, chest, or back)
Acne, often along the jawline and chin
Androgenic alopecia (thinning hair on the scalp)
Oily skin

You might also notice physical signs like acanthosis nigricans, those dark, velvety patches of skin around the neck, armpits, or groin. Losing weight feels nearly impossible, even with diet and exercise.

The link between insulin resistance and PCOS symptoms creates a cycle that's hard to break. Insulin resistance leads to weight gain, especially visceral fat (fat stored deep around your internal organs, which is more metabolically harmful than fat under the skin). That extra weight then makes insulin resistance worse.

Hormonal imbalances and their impact on fertility

Irregular periods are a huge complaint. Some women go months between periods, while others have unpredictable bleeding. This happens because high androgen and insulin levels disrupt normal ovulation.

The hormonal imbalance hits fertility, too. Without regular ovulation, getting pregnant gets a lot harder. PCOS is one of the leading causes of infertility in women.

Long-term health risks associated with PCOS

PCOS isn't just about the symptoms you notice now. It carries some serious long-term health risks.

Women with PCOS are much more likely to develop type 2 diabetes. The insulin resistance that drives PCOS can progress to diabetes if you don't manage it. Some studies suggest the risk is four to seven times higher than in women without PCOS.

Metabolic syndrome shows up more often, too. This is a cluster of conditions, high blood pressure, abnormal cholesterol, and excess visceral fat, that together raise your risk of heart disease and type 2 diabetes.

The endometrial lining can also get thick if periods are irregular or absent. When the uterine lining doesn't shed regularly, it builds up and increases the risk of endometrial cancer. Women who go months without a period should speak to their GP about this.

The combination of obesity, insulin resistance, and hormonal imbalances means you need ongoing management to avoid these complications.

How Mounjaro works for PCOS

Mounjaro takes a different approach from older weight loss medications and PCOS treatments. It works on two hormone pathways at once, not just one.

This dual action helps improve insulin resistance, reduces appetite, and may restore hormonal balance in ways that single-pathway treatments cannot.

A woman in her 30s standing thoughtfully, holding a stylised Mounjaro pen, surrounded by icons representing the two hormone pathways GLP-1 and GIP.

Mechanism of action: tirzepatide and hormonal pathways

Tirzepatide (the active ingredient in Mounjaro) is a dual GLP-1 and GIP receptor agonist. Most weight loss injections target just one pathway — GLP-1. Mounjaro targets both, mimicking natural gut hormones your body releases after eating.

GLP-1 (glucagon-like peptide-1) and GIP (glucose-dependent insulinotropic polypeptide) are hormones that help regulate blood sugar and appetite.

When tirzepatide activates GLP-1 receptors, it tells your pancreas to release more insulin when blood sugar is high. It also blocks glucagon, a hormone that raises blood sugar. At the same time, Mounjaro slows how quickly food leaves your stomach, helping you feel full longer.

The GIP part of tirzepatide works alongside GLP-1 to boost insulin release even more. It also changes how your body stores and processes fat and may help reduce inflammation.

Early research suggests this dual action may be more effective than GLP-1-only medications for weight loss. This is particularly relevant for PCOS, where losing even 5% of your body weight can boost ovulation and lower testosterone.

For women with PCOS, improving insulin resistance means the ovaries aren't constantly pushed to produce excess androgens. This can lead to more regular periods, less excess hair, fewer breakouts, and improvements in menstrual regularity.

You'll start on 2.5mg once weekly for 4 weeks. Your dose increases every 4 weeks through 5mg, 7.5mg, 10mg, 12.5mg, up to a maximum of 15mg once weekly, depending on your response and how well you tolerate it. For more details, see the Mounjaro Summary of Product Characteristics.

Regulating blood sugar and appetite

Mounjaro manages blood sugar by increasing insulin release only when glucose is high. Unlike some older diabetes medications, it's much less likely to cause your blood sugar to drop too low between meals.

Tirzepatide also suppresses glucagon. Normally, glucagon tells your liver to release glucose. By blocking this, Mounjaro keeps blood sugar from spiking.

The appetite effects are pretty noticeable. Mounjaro slows gastric emptying, so food stays in your stomach longer. You feel full sooner and stay satisfied between meals. Many people end up eating less without feeling deprived.

Comparison with other medications

How does Mounjaro compare to other PCOS treatments?

Metformin has been the standard for years. It improves insulin sensitivity and helps with modest weight loss. But research comparing GLP-1 receptor agonists to metformin found that GLP-1 medications were more effective at improving insulin sensitivity in women with PCOS. Mounjaro's dual action may offer even more.

Semaglutide (Ozempic, Wegovy) is a GLP-1-only medication. It works for weight loss and blood sugar control. But since Mounjaro targets both GLP-1 and GIP, clinical trials showed higher average weight loss with tirzepatide compared to semaglutide, 22.5% vs 15% at maximum doses, though no head-to-head trials exist specifically in women with PCOS, and individual responses vary.

Orlistat blocks fat absorption in your gut. It can cause some pretty uncomfortable digestive side effects and usually leads to less weight loss than GLP-1 medications. It doesn't really address insulin resistance, either.

It's worth noting that Mounjaro works very differently from insulin-based treatments like insulin glargine, a long-acting insulin used to manage blood sugar in type 2 diabetes. While insulin glargine replaces or supplements your body's insulin supply, Mounjaro improves how your body responds to its own insulin and reduces appetite. That's a fundamentally different approach, and one that's more suited to the insulin resistance seen in PCOS.

Zepbound is just the brand name for tirzepatide when prescribed for weight management. Same active ingredient as Mounjaro.

Mounjaro has been approved by NICE (the body that assesses treatments for the NHS) for weight management.

A comparison infographic showing four PCOS medications side by side: Mounjaro, Metformin, Semaglutide, and Orlistat, with key differences highlighted.

Benefits and considerations for Mounjaro in PCOS management

Mounjaro offers some real advantages for women with PCOS, especially with weight loss and improved insulin function.

Still, it's important to weigh these benefits against possible side effects and your own health situation.

Weight loss and metabolic improvements

For a lot of women with PCOS, losing weight feels like pushing a boulder up a hill. The condition itself makes weight management harder thanks to insulin resistance and hormone swings.

In clinical trials (SURMOUNT-1), people taking tirzepatide at the highest dose (15mg) lost an average of 22.5% of their body weight over 72 weeks, with results ranging from 15–22.5% depending on dose. Individual results vary significantly.

Even dropping just 5% of your body weight can ease PCOS symptoms. Modest weight loss helps restore more regular periods and can lower testosterone levels.

The metabolic improvements go beyond the number on the scales. Blood pressure often drops, and HbA1c levels (a blood test that shows your average blood sugar over the past 2–3 months) usually improve. These changes lower the risk of developing type 2 diabetes, which is higher in women with PCOS.

Improving insulin sensitivity and reducing androgens

By improving insulin resistance, Mounjaro helps your cells respond to insulin better, so your body doesn't have to produce as much. Lower insulin levels mean your ovaries don't get that constant push to make androgens. As a result, you might see less excess hair, fewer breakouts, and maybe even notice your scalp hair thinning less.

Some women spot these changes within just a few months of starting Mounjaro. Improvements in insulin sensitivity often show up pretty quickly, sometimes even before the scale starts to budge.

Impact on menstrual regularity and fertility

Irregular periods are a classic PCOS frustration. Some women go months without a period, while others deal with cycles so unpredictable it makes planning feel impossible.

Mounjaro helps regulate cycles by tackling hormonal disruption at its source. When your insulin drops and androgens calm down, your body's normal ovulation signals can finally get through.

Studies show women on similar medications get more regular bleeding patterns. A lot of these fertility improvements seem to go hand-in-hand with losing even a little weight.

If you're trying to conceive, restoring ovulation is everything. Mounjaro may help by nudging your cycles back on track. It might even improve the health of your uterine lining, which matters for implantation.

Important: Mounjaro may reduce the effectiveness of oral contraceptives. Use additional barrier contraception (such as condoms) for 4 weeks after starting treatment and for 4 weeks after each dose increase. This is especially important if you're using hormonal contraception to manage PCOS symptoms. Mounjaro is not recommended during pregnancy or if you're actively trying to conceive. Speak to your prescriber about the right timing if pregnancy is part of your plan.

Potential risks and side effects

Like any medication, Mounjaro comes with its own set of possible side effects. Most of them affect your digestive system.

These side effects are common and usually settle down on their own

Mild nausea, especially in the first week or two after a dose change
Reduced appetite (this is actually part of how the medication works)
Occasional loose stools or mild constipation
Mild injection site redness

These typically improve within 2–4 weeks as your body adjusts to each dose.

Side effects are most common in the first few weeks after each dose increase. Starting with a low dose and ramping up slowly helps a lot. Eating smaller meals and steering clear of strong smells can also make nausea easier to handle.

An infographic showing common Mounjaro side effects and management tips: nausea managed by small meals, constipation managed by hydration, and reduced appetite managed by nutrient-dense foods.

Seek immediate medical help if you experience

Severe abdominal pain that doesn't go away, especially if it radiates to your back (possible pancreatitis)
Signs of allergic reaction: swelling of the face, lips, or throat, or difficulty breathing
Severe or persistent vomiting that won't stop
Sudden changes in vision

Call 999 for suspected allergic reactions.

See your GP if you notice

Persistent nausea or vomiting that doesn't improve after 2–4 weeks
A lump or swelling in your neck
Difficulty swallowing or persistent hoarseness
Signs of gallbladder problems (pain in the upper right side of your stomach)
Symptoms of low blood sugar if taking other diabetes medications

Mounjaro is not suitable if you or a close family member have a history of medullary thyroid cancer, or a rare condition called multiple endocrine neoplasia syndrome type 2 (MEN2). Your prescriber will ask about these before prescribing.

Blood pressure can shift too, though Mounjaro often helps people with high blood pressure lower it. Regular monitoring is a good idea.