Mounjaro and Smelly Urine: What to Know (October 2026)

01 · The core answer

Is smelly urine caused by Mounjaro?

Smelly urine is not listed as a side effect in the UK patient leaflet. Our wider guide to whether Mounjaro can cause smelly urine covers the same question from another angle.

What the medicine does do is help you feel fuller sooner and slow how quickly the stomach empties.¹ For many people that means eating and drinking differently from before. A change in routine is a sensible thing to look at first.

02 · Your next step

What should you do if you notice it?

Start with the simple things: think about what you have eaten and drunk lately, and whether you have been drinking less than usual. If the smell settles within a few days, there is usually nothing more to do.

If it persists, or comes with pain, fever, blood or feeling unwell, speak to your GP or prescriber rather than waiting. You can also read our overview of Mounjaro and urine changes. If you are weighing up treatment, our weight loss clinic explains how a prescriber-led programme works.

03 · Food and fluids

Eating, drinking and urine smell

Urine smell commonly changes with how much you drink and what you eat. When appetite falls, meals and drinks can both shrink without you noticing. Mounjaro is used alongside a reduced-calorie diet and increased physical activity, so a changed diet is part of treatment.²

Keeping a regular routine of fluids through the day is a practical habit. If you are unsure how much is right for you, ask your prescriber at your monthly review.

04 · Ketones and sweet smells

What about ketones or a sweet smell?

Many people ask whether ketones explain a changed smell. We cover that in detail in our guide to ketones in urine on Mounjaro.

If your urine smells sweet or fruity and you cannot explain it, have it checked by a GP. Do not try to work out the cause from the smell alone.

05 · When to get checked

When a smell needs medical advice

Speak to your GP or prescriber if a strong smell lasts, or if it comes with any of these.

• Pain or burning when passing urine
• A frequent or urgent need to go
• Fever, chills or pain in your back or side
• Blood in your urine, or a clear colour change
• Feeling generally unwell, very thirsty or very tired

Related changes have their own guides: blood in urine, dark urine and protein in urine.

06 · Reporting symptoms

Reporting a suspected side effect

If you think a symptom may be linked to your medicine, tell your prescriber and consider reporting it through the Yellow Card scheme.¹⁹ Reports help the regulator spot patterns over time.

Customers on treatment with us have ongoing monthly reviews with the prescribing team, including side-effect support. Treatment is only supplied after a free online consultation reviewed by a GPhC-registered prescriber.

07 · Serious side effects

Serious side effects: when to get help straight away

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/eyes (possible gallbladder problems); or signs of a severe allergic reaction such as swelling of the face or throat and difficulty breathing. If you take insulin or a sulfonylurea alongside Mounjaro, watch for low blood sugar (shakiness, sweating, confusion) — your prescriber may need to adjust those medicines.¹