GLP-1 medicines and endometriosis

Over the past year many people with endometriosis will have seen stories online of people whose pain improved after starting one of these weight-loss injections, and they want to know whether it might help them too.

Do GLP-1 medicines treat endometriosis?

Not at this stage. No completed clinical trial has tested them in people with endometriosis, and they aren’t approved for it in New Zealand or anywhere else.

For some people who have endometriosis and are also living with excess weight, insulin resistance, type 2 diabetes or PMOS, a GLP-1 medicine may be worth discussing as part of a wider plan. In that situation there’s an established reason to use it, and any effect on endometriosis symptoms would be a possible extra rather than the main aim.

What are GLP-1 medicines?

GLP-1 (glucagon-like peptide-1) is a hormone your gut releases after you eat. It helps control blood sugar, slows the emptying of your stomach and makes you feel full sooner.

GLP-1 medicines copy this hormone. These are the ones available in New Zealand:

Mounjaro works slightly differently from the others because it also acts on a second gut hormone called GIP.

Ozempic is often in the news. It’s the same medicine as Wegovy, but in New Zealand it’s approved only for type 2 diabetes, so semaglutide for weight management is prescribed as Wegovy.

These medicines work well for type 2 diabetes and weight management. They also seem to reduce inflammation in the body, which is part of why researchers are looking at them in other conditions.

Why are researchers looking at endometriosis?

Endometriosis is now understood as a long-term inflammatory condition, not only a problem in the pelvis. It can involve the immune system, the nerves and pain pathways, and the way the body forms scar tissue. A few early findings have prompted interest in GLP-1 medicines:

• One study found lower GLP-1 levels in the pelvic fluid of women with endometriosis. This shows an association only. It doesn’t tell us that low GLP-1 causes endometriosis, or that giving a GLP-1 medicine would help.
• GLP-1 medicines reduce inflammation and scarring in other conditions, and both play a part in how endometriosis lesions grow and cause pain.
• Laboratory research suggests GLP-1 may affect pain signalling in the nervous system.
• Endometriosis affects people of all sizes. For those carrying extra weight, losing some can make pain easier to manage, surgery safer and fertility treatment more likely to work.

What does the evidence show so far?

There are no completed clinical trials of GLP-1 medicines in endometriosis. What we have comes from laboratory studies, theories about how the medicines might work, and personal stories.

Personal stories can’t tell us much on their own. Endometriosis symptoms naturally vary over time, and people who lose weight often change other things too, such as exercise, diet or other medicines. Only a proper trial can show whether the medicine is responsible.

We already have treatments for endometriosis that are well supported by evidence. These include hormonal treatments (such as the Mirena, progestogen tablets and the combined pill), minimally invasive surgery (laparoscopy), and specialist pain management including pelvic physiotherapy. A GLP-1 medicine shouldn’t replace any of these.

Who might discuss it with me?

A GLP-1 medicine may be worth talking about if you have endometriosis and also:

• Have a BMI in the range where weight-management medicines are recommended
• Have insulin resistance, prediabetes or type 2 diabetes
• Have PMOS (PCOS)
• Are hoping to lose weight before surgery or fertility treatment.

It’s usually not a good choice if you’re already a healthy weight, are pregnant or planning a pregnancy soon, or have had an eating disorder.

Safety

Side effects

Nausea, vomiting, diarrhoea, constipation and reflux are common, especially when starting or increasing the dose. They usually settle with time. Gallstones and pancreatitis are rarer but more serious.

Pregnancy

These medicines shouldn’t be used in pregnancy. If you’re planning to conceive, Wegovy should be stopped at least two months before you start trying. Mounjaro, Saxenda and the diabetes medicines have their own advice. Fertility can improve with weight loss, so unplanned pregnancies do happen.

Contraception

Use reliable contraception while you’re on any of these medicines.

• Mounjaro can reduce how well the contraceptive pill is absorbed. If you take the pill, use condoms as well, or change to a non-oral method, for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase.
• Wegovy, Saxenda, Trulicity and Victoza haven’t been shown to affect the pill in a meaningful way. Vomiting or severe diarrhoea can still stop the pill working, whichever medicine you’re on.
• Many endometriosis treatments, such as the Mirena, aren’t tablets, so they aren’t affected.

Muscle and nutrition

Fast weight loss can include some muscle loss. Eating enough protein and doing some strength exercise helps protect it.

Stopping

Weight often comes back when these medicines are stopped, so they’re usually treated as a long-term medicine.

Cost and access in New Zealand

Wegovy, Mounjaro and Saxenda are approved by Medsafe for weight management, but at the time of writing none is publicly funded for this use. You would pay the full cost, roughly $430 to $900 a month depending on the medicine and dose. In May 2026 Pharmac added Wegovy to its list of medicines it would like to fund when budget allows, but there’s no confirmed date.

If you have type 2 diabetes, Trulicity and Victoza are funded for people who meet Pharmac’s criteria. Your GP can advise whether this applies to you.

Questions to bring to your appointment

1. Is there a medical reason, apart from endometriosis, that a GLP-1 medicine might suit me?
2. How would it fit with my current endometriosis treatment?
3. What contraception should I use while taking it?
4. How long would I need to stop before trying for a baby?
5. What side effects should I watch for, and what monitoring will I need?
6. What will it cost, and for how long would I take it?

Summary

GLP-1 medicines aren’t a proven treatment for endometriosis, and they don’t replace the treatments we know work. Research is under way, and I understand why people are hopeful.

If you also have weight or metabolic concerns, one of these medicines may be a reasonable addition to your care, and I’m happy to talk through whether that applies to you. If you’re struggling with pelvic pain now, please don’t wait for new medicines. There’s a lot we can already do to help.

This article is general information and doesn’t replace personal medical advice. Please talk to your own doctor before starting or changing any medicine.