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Can Mounjaro cause erectile dysfunction?

5 min read time

Written by: Sunny Dhain

Medically reviewed by: Tannaz Sohrabi

Published 10/09/2025 Updated 30/07/2026

No. Erectile dysfunction isn’t a listed side effect of Mounjaro, and a 2025 study found men taking tirzepatide were significantly less likely to develop ED than men on comparable treatments.

Worried about a side effect? Speak to a clinician

Is ED a side effect of Mounjaro?

Not a recognised one. Erectile dysfunction doesn’t appear among the adverse reactions in the UK Summary of Product Characteristics for Mounjaro. The listed side effects are mostly gastrointestinal: nausea, diarrhoea, vomiting, constipation, plus fatigue, dizziness and injection site reactions.

What the research shows

A 2025 cohort study followed men aged 18–70 with type 2 diabetes and no history of ED, using matched groups from the TriNetX research network. Men on tirzepatide were:

30% less likely to develop ED than those on sitagliptin

33% less likely than those on injectable semaglutide

45% less likely than those on dulaglutide

The researchers attribute this to tirzepatide’s metabolic effects. ED is often a vascular problem, and better blood sugar control and weight loss both improve vascular health.

Separately, a systematic review of seven studies (371 men) found that GLP-1 treatment was associated with increased total testosterone, particularly in obese men, as well as improved sperm concentration and motility.

Two limits on this: It’s observational, so it shows association rather than cause, and the authors call for randomised trials. It also covered men with type 2 diabetes, who start from higher ED risk than average.

Mounjaro is not a treatment for erectile dysfunction and isn’t licensed as one.

Why some men still report problems

Several things that genuinely happen on Mounjaro can affect sex indirectly. Most settle.

Nausea – Common in the first weeks and after each dose increase. Enough on its own to explain a temporary drop in interest.

Fatigue – Rapid weight loss on a much reduced calorie intake is tiring, and tiredness is an underrated cause of low libido.

Eating too little – Appetite suppression can tip into undereating, which affects energy and hormone production.

Low blood sugar – Uncommon with Mounjaro alone, but a real consideration alongside insulin or sulfonylurea. Causes fatigue, shakiness and poor concentration.

Hormonal readjustment. Losing fat usually raises testosterone over time, but some men feel flat during the transition.

Stress and anxiety – Established causes of ED, and starting a new injectable while your body changes quickly supply plenty of both.

Mounjaro and libido

Reduced sex drive isn’t a listed side effect either, or it’s usually downstream of the factors above rather than a direct drug effect. It tends to improve as weight, blood sugar, and energy levels do. Some people report libido increasing as they lose weight. Both are normal.

What to do about it

Don’t stop treatment on your own. If the cause is undereating or low blood sugar, stopping treats the wrong problem, and you lose the metabolic benefit that’s most likely to help in the long term.

Give it a few weeks, especially after a dose increase.

Check the basics: eating enough, protein intake, sleep, alcohol.

On insulin or sulfonylurea? Check blood sugar around the times symptoms occur.

If it persists, get bloods done: testosterone, HbA1c, lipids, blood pressure.

Speak to your prescriber or to us.

Report suspected side effects via the MHRA Yellow Card scheme.

One thing not to ignore: persistent ED can be an early sign of cardiovascular disease or undiagnosed diabetes, sometimes years before anything else shows up. New and ongoing symptoms need to be investigated, not just treated.

Symptoms not settling? Get it looked at properly

Our clinicians review your answers, checks your current medicines for interactions, and tell you whether treatment or further investigation is the right next step. Usually reviewed the same day.

ED Treatment Alongside Mounjaro

There’s no known interaction between tirzepatide and the PDE5 inhibitors used for ED, and they’re commonly prescribed together. An assessment is still needed, mainly because ED treatments can’t be taken with nitrates prescribed for chest pain.

See our erectile dysfunction page for treatment options such as sildenafil and tadalafil. If you’d rather talk it through first, you can message our clinical team.

Frequently Asked Questions

Does Mounjaro cause erectile dysfunction?

No. It isn’t a listed side effect; studies of people using Mounjaro have shown they had a lower risk of ED than men on comparable treatments.

Can Mounjaro lower testosterone?

Evidence suggests the opposite. A systematic review found GLP-1 treatment associated with increased testosterone, particularly in obese men.

Should I stop Mounjaro if I get ED?

Speak to your prescriber first. The cause is often addressable without stopping.

Can I take Viagra or Cialis with Mounjaro?

There’s no known interaction, but ED treatments are prescription-only and need an assessment.

Will losing weight improve my erections?

Often, obesity contributes to ED through its effects on blood vessels, blood sugar and hormones.

Still not sure?

How we reviewed this article:

Sources

Mounjaro KwikPen — Summary of Product Characteristics (2026) Electronic Medicines Compendium (EMC) [accessed 29th July 2026]
Association of tirzepatide with erectile dysfunction in people with type 2 diabetes (2025) Journal of Diabetes and its Complications [accessed 29th July 2026]
Effects of GLP-1 Receptor Agonists on Testosterone Levels and Semen Parameters in Men: A Systematic Review (2025) International Continence Society, ICS 2025, Abstract 166 [accessed 29th July 2026]

Current version
30th Jul 2026 Edited by: Sunny Dhain, MPharmRS PGDip IndP
29th Jul 2026 Medically reviewed by: Tannaz Sohrabi

Medically reviewed by:

Tannaz Sohrabi

Tannaz is Governance Pharmacist at The Family Chemist, where she leads the clinical governance and safety standards of the pharmacy and online clinic. With extensive experience across both hospital and community pharmacy, she brings a strong clinical background and a deep understanding of patient care to the service.

Last reviewed: 29th Jul 2026

Meet our team

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