Can Mounjaro Cause Cold Feet — and Should You Be Concerned?

What the clinical programme actually found — and what it stayed silent on

The SURMOUNT trials, which enrolled thousands of adults and produced the evidence base behind Mounjaro's UK licence, reported a well-characterised side-effect profile dominated by gastrointestinal symptoms: nausea, diarrhoea, constipation and indigestion top the list, as the NHS tirzepatide medicines page sets out in detail. Cold feet do not appear in that profile, and that absence is not the same as saying it cannot happen; it means the trials did not find it occurring more often in the tirzepatide group than in people taking a placebo.

What the trials did confirm, unambiguously, is significant weight loss. In SURMOUNT-1, participants on the 15mg dose lost around 20–21% of their body weight on average over 72 weeks. That scale of change carries its own physiological consequences, and feeling colder is one of them. The cold sensation many people notice on Mounjaro almost certainly belongs in that category rather than in a separate, medicine-specific bucket.

This distinction matters practically. It shapes whether the right response is adjusting treatment or simply layering up and eating enough protein. You can read a fuller look at the cold-on-treatment experience on our cold on Mounjaro page.

Why weight loss itself makes feet feel colder

Fat is not inert. It stores energy, yes, but it also acts as insulation and contributes to the metabolic rate that generates body heat. When body weight drops quickly, two things happen at once: resting metabolism slows slightly as the body adjusts to its new size, and the subcutaneous fat layer that buffers the skin from cold thins out. The result is that extremities, which have the highest surface-area-to-volume ratio in the body, lose heat faster than before.

There is also a circulatory element. Blood flow to the hands and feet is the first thing the body throttles when it prioritises warmth for core organs. In someone losing weight rapidly, peripheral circulation can be more variable than usual. None of this is dangerous in itself; it is the body doing exactly what bodies do during an energy deficit. The practical fix is often simple: eat regular warm meals, stay well hydrated, keep moving, and wear an extra pair of socks.

A common misconception worth gently addressing: some people worry that cold feet signal that Mounjaro is affecting the nerves or blood vessels of the legs directly. There is currently no clinical evidence to support that. The broader picture of foot-related symptoms on Mounjaro is worth reading if this is on your mind.

When cold feet deserve more than a warm pair of socks

Most cases of cold feet on Mounjaro will settle once the body has adapted to a new, lower weight and calorie level. But some presentations call for proper medical assessment, and it is important to be clear about them.

Seek prompt advice from your GP or a clinician if the coldness is one-sided, if it comes with pain, pallor or a bluish tinge, if one foot feels noticeably colder than the other, or if you also have numbness or tingling that does not resolve. These features can point to peripheral arterial disease, Raynaud's phenomenon, or a neurological issue, none of which are caused by Mounjaro but all of which can be aggravated or masked by treatment-related changes.

If you have questions specific to your situation, our clinical support team is available seven days a week. And for anything that feels urgent, your GP or 111 is the right first call. The MHRA's Yellow Card scheme also allows patients to report any suspected side effect, which helps build the evidence base for all GLP-1 medicines over time.

People sometimes ask whether this cold feeling might indicate something neurological, such as nerve involvement. That question comes up enough that we have a page looking at whether Mounjaro has any connection to neurological symptoms, the short answer, based on current evidence, is reassuring, but the full picture is there if you want it.

For a broader overview of how tirzepatide works and what to expect, the tirzepatide overview pulls together the mechanism, the trial evidence and the eligibility criteria in one place. If you are weighing up whether to start treatment, our prescribers can also clarify whether starting Mounjaro requires you to notify your GP, and the free consultation with our prescribers is the right place to bring all of these questions together, a real clinician reviews every case the same day.