GLP-1 Sexual Side Effects: What the Evidence Says (October 2026)

01 · The core answer

Do GLP-1 medicines cause sexual side effects?

For Mounjaro, the honest answer is that sexual side effects are not a listed side effect in the SmPC or the patient information leaflet.¹¹³ It does not mean nobody has ever noticed a change in their sex life while taking it.

Does the drug act directly on desire or arousal? Do its known effects, such as tiredness or nausea, get in the way indirectly? And could a big change in weight and routine alter how you feel about your body and your relationships?

Mounjaro activates the GIP and GLP-1 receptors, helps regulate appetite and slows how quickly the stomach empties.¹

02 · Direct and indirect routes

Direct effects versus indirect effects

03 · Your next step

What to do if your sex drive has changed

Start by noting when the change began relative to your dose. If it followed a dose increase and sits alongside tiredness or nausea, it may ease as your body adapts, because most side effects appear in the first days after a start or increase, peak early and settle.¹ If you find a dose hard to tolerate, prescribers can hold the current dose longer before stepping up, so speak to your clinical team rather than pushing through.

If the change persists, is distressing, or involves pain or loss of function, tell your prescriber. Other causes are common and treatable: stress, relationship strain, hormonal changes, other medicines, and health conditions unrelated to weight. Report anything you suspect is a side effect through the Yellow Card scheme.

Our team offers side-effect support alongside ongoing monthly reviews.

04 · Fatigue and energy

Fatigue, low energy and desire

Fatigue is a recognised common side effect and the most plausible everyday reason someone feels less interested in sex. It is most noticeable in the first weeks and after dose increases.¹

It usually reflects a mix of the body adjusting and simply eating less. Keeping meals balanced, with protein especially, staying hydrated and keeping gentle activity going all help. For most people energy returns to normal within a few weeks. Tell your clinical team if tiredness is severe or not settling.¹

Tiredness is easy to underestimate. When your energy is low, desire is often one of the first things to go quiet, and this is true of many illnesses and diets, not only this medicine. If your desire dipped at the same time as your energy and returned as your energy did, that pattern points to the indirect route rather than anything specific to sex.

05 · Digestive effects

Digestive effects and intimacy

Most side effects of Mounjaro are digestive. The most common are nausea, diarrhoea, vomiting, constipation and abdominal discomfort. Indigestion, reduced appetite, dizziness, reflux and burping are also common.¹ Feeling bloated, queasy or unpredictable in your bowels can make physical closeness less appealing, even when your underlying desire is unchanged.

Practical steps that help most people are to eat smaller meals slowly, stop at the first feeling of fullness, favour plain lower-fat foods while adjusting, stay well hydrated and avoid lying down straight after eating.¹ If nausea or vomiting is persistent or you cannot keep fluids down, contact your clinical team — dehydration needs prompt attention.

Our guide to gastrointestinal side effects goes into these in more depth. In the weight-management trials, nausea, vomiting and diarrhoea were more common while the dose was being increased and became less frequent over time.¹

06 · Mood and body image

Mood, body image and desire

Regulators have looked specifically at whether GLP-1 medicines are linked to low mood or suicidal thoughts, and the EMA's safety committee concluded in 2024 that the evidence does not support a causal link. The MHRA keeps this under continuous review.¹⁷

If you have thoughts of harming yourself or ending your life, get help straight away. Call 999 or go to A&E if you are in immediate danger. In England you can call NHS 111 and choose the mental health option, any time. You can also call Samaritans free on 116 123, day or night. Tell your prescriber about any change in your mood while taking Mounjaro.

That said, any big change in weight, appetite and routine can affect how you feel. Tell your prescriber about any history of depression, and seek help promptly if your mood drops or you have distressing thoughts during treatment.¹⁷

Body image can cut both ways. Some people feel more confident as weight falls; others find rapid change unsettling. Hair shedding is a recognised side effect linked to rapid weight loss itself rather than a direct drug effect, and for most people it settles as weight stabilises.¹ A loss pace guided by your prescriber, rather than maximum speed, also helps protect lean mass and how you feel in your body.

07 · Women and contraception

GLP-1 side effects in women: contraception and desire

For women, the one clearly documented interaction relevant to sex life is with oral contraception. The SmPC advises switching to a non-oral method, or adding a barrier method (such as condoms), for 4 weeks after starting Mounjaro and for 4 weeks after each dose increase.¹ Mounjaro can reduce absorption of oral contraceptives because it slows how quickly the stomach empties.⁷ Speak to your prescriber about what contraception is appropriate while you are on treatment, and do not assume your usual pill is working as before.

Changes in desire or arousal are not listed in the product information, so they are not established effects of the medicine.¹ If you notice such changes, they are still worth raising with your prescriber, because hormonal shifts, stress, other medicines and low energy can all play a part and some are treatable.

Our page on side effects of GLP-1 agonists covers the wider list women ask about.

08 · Men and function

GLP-1 side effects in men: desire and erections

For men, the same principle applies. Erectile difficulty and low desire are not listed side effects of Mounjaro, so they are not established effects of the medicine.¹ Where men do notice a change, the likeliest explanations are indirect: tiredness, an unsettled stomach, eating less and mood.

A change that appears alongside treatment is therefore not automatically caused by it.

If you want help with erectile problems, a prescriber can review your history and medicines together. We are a full UK online pharmacy with a sexual health service as well as weight loss, so you can raise both in your consultation rather than treating them separately.

09 · Other medicines

Other medicines that can affect sex drive

People often ask whether other medicines they take, such as metformin, have sexual side effects. Check the patient leaflet for each one, and ask your pharmacist or prescriber to review your full list, because the cause of a change may be a medicine you have taken for years rather than the new one.

If you take insulin or a sulfonylurea alongside Mounjaro, watch for low blood sugar (shakiness, sweating, confusion), because your prescriber may need to adjust those medicines.¹ Feeling shaky or confused is not something to push through for the sake of intimacy.

The same caution applies to low-cost supplements sold as natural alternatives. They come with no clinical oversight and dosing is not standardised; our guide to side effects of GLP-1 supplements explains more.

10 · Stopping and side effects

Why some people stop treatment

Most people tolerate treatment, but some stop because of side effects. In SURMOUNT-1, 4.3% of people on 5mg, 7.1% on 10mg and 6.2% on 15mg stopped treatment because of side effects, compared with 2.6% on placebo.² Those trial figures concern side effects as a whole and are not specific to sexual health.

If a dose is hard to tolerate, the gradual dose ladder exists for a reason, and prescribers can hold the current dose longer before stepping up. Our guide to weight loss side effects sets out what to expect at each stage.

Stopping should always be planned with your prescriber. In SURMOUNT-4, people who stopped tirzepatide after 36 weeks regained on average 14% of body weight over the following year, while those who continued treatment lost a further 5.5% on average.

11 · Serious effects and reporting

Serious side effects and Yellow Card reporting

Serious side effects are uncommon but need urgent attention. Seek immediate medical help for severe, persistent stomach pain that may spread to your back, with or without vomiting (possible pancreatitis), pain in the upper right abdomen, fever or yellowing of skin or eyes (possible gallbladder problems), or signs of a severe allergic reaction such as swelling of the face or throat and difficulty breathing.¹

For anything that does not fit these, including a change in sexual function, the right route is your prescriber first. You can also report a suspected side effect to the MHRA through the Yellow Card scheme.¹⁹

Our GLP-1 side effects guide and the overview of GLP-1 medication side effects give more detail. For the Mounjaro-specific view, see Mounjaro sexual side effects. Mounjaro is a prescription-only medicine, supplied only after an online consultation reviewed by a GPhC-registered prescriber, and used alongside a reduced-calorie diet and increased physical activity. Individual results vary.