Can Mounjaro Give You Chills? (October 2026)

01 · The short answer

Does Mounjaro give you chills?

Chills are not on the list of side effects in the UK product information for Mounjaro, so they are not an established effect of the medicine.¹¹³ That does not mean your experience is imaginary. It means a link between the two has not been established. Treating Mounjaro as the automatic culprit could cause you to miss another cause.

If you feel cold or shivery after starting treatment or after a dose increase, the sensible approach is practical. Note when it happens, whether you have a temperature, and whether you have other symptoms. Then tell your prescriber.

02 · Your next step

What to do if you feel chilly or shivery

Start by checking for signs of illness, because that is the most important thing to rule out. Take your temperature if you can. Note whether you have a cough, sore throat, urine symptoms, a rash or aching. Chills together with a fever are not a pattern the product information describes for Mounjaro, so they deserve proper attention. Our page on Mounjaro fever and chills goes into that combination.

If you feel cold without any other symptoms, keep a short diary for a week or so. Record the day you inject, what you have eaten and drunk, how you slept, and when the feeling comes. A pattern, or no pattern, gives your prescriber something concrete to work with.

If you are unsure, ask. Our prescribing team offers side-effect support as part of ongoing monthly reviews, and you can read about the Mounjaro pen and how to start if you are considering treatment.

Related guides: Can mounjaro cause chills and Does mounjaro cause cold chills.

03 · What the label says

What the product information says

The Mounjaro SmPC and patient leaflet list the side effects that have been identified, and chills are not among them.¹¹³ That is the starting point for any honest answer.

Product information is updated over time as new safety data arrive. The route by which that happens is reporting. If you think a symptom could be related to your medicine, you can report it yourself through the MHRA Yellow Card scheme.¹⁹ Your report helps regulators spot patterns that no single prescriber would see.

It is also worth reading the leaflet in your box for the full list of what is documented. Symptoms that are listed there come with guidance on what to do. Symptoms that are not listed still deserve a conversation with your prescriber, especially if they are new, persistent or worrying.

04 · Other possible explanations

Other things that can make you feel cold

Feeling cold has many everyday causes, and several overlap with the period when people start treatment. These are possible explanations, not established effects of Mounjaro.

• A passing illness.
• Eating less. Mounjaro is used alongside a reduced-calorie diet, and most people feel fuller sooner and less hungry between meals.¹
• Not drinking enough. A smaller appetite can mean smaller drinks as well.
• Poor sleep or stress. Both can change how warm or cold you feel.
• Room and clothing changes. A change in season, or in how your clothes fit as your body changes, can alter how comfortable you feel.
• Other medical conditions.

None of this is a substitute for assessment. If the feeling is new, lasting or worrying, a prescriber or GP can check for the causes that matter.

05 · Chills versus fever

Chills, fever and feeling unwell

Chills together with a temperature are a reason to seek advice, not a reason to wait. Shivering is the body's response to feeling cold or to a rising temperature, so it can be a sign of an infection that has nothing to do with your injection.

Gastrointestinal effects are documented for Mounjaro, and the leaflet explains what to look for and when to speak to a doctor or pharmacist.¹³ If you have severe or persistent stomach pain, get medical help straight away. If you cannot keep fluids down, contact your clinical team — dehydration needs medical help straight away. Do not assume it is just your treatment settling in.

Get medical help straight away for any of the following with chills:

• severe, persistent stomach pain that does not settle
• difficulty breathing or swelling of the face, lips or throat
• confusion, extreme drowsiness or fainting

If you are in doubt, use the NHS urgent advice service or call emergency services.

06 · Low blood sugar

Low blood sugar and shakiness

If you take insulin or a sulfonylurea alongside Mounjaro, the doses of those medicines may need adjusting because of the risk of low blood sugar.¹¹³ They are not forbidden together. They simply need review by whoever prescribes them.

Shakiness, sweating and feeling cold and clammy are the kinds of signs that people with diabetes are taught to treat as a possible low blood sugar. If that describes you, follow the plan agreed with your diabetes team and tell them what happened.

If you do not have diabetes and do not take those medicines, tell your prescriber about episodes of shakiness or sweating so they can consider what else might be going on. Please do not self-diagnose or adjust any dose.

07 · Timing and doses

Does timing or dose change matter?

Mounjaro starts at 2.5mg and steps up through 5mg, 7.5mg, 10mg, 12.5mg and 15mg, with dose changes made by your prescriber.¹ That is why noting the date of each injection and each increase is useful.

If a feeling of being cold seems to follow your injection day or a step up, write it down. Your prescriber can then judge whether it fits any documented pattern, or whether to look elsewhere. A written record turns a vague worry into usable information.

Please do not skip, delay or split doses to see whether the symptom changes. Altering your schedule outside the licence is not something we can support. If you miss a dose, take it as soon as you can within 4 days (96 hours) of the scheduled time; if more than 4 days have passed, skip it and take the next one on your normal day — never take two doses within 3 days of each other.

08 · Itchy skin and other new symptoms

What about itchy skin and other new symptoms?

Itching is listed in the UK patient leaflet as a common side effect (up to 1 in 10 people), as part of allergic reactions such as rash, itching or eczema.¹³ For any new or lasting symptom, including feeling generally unwell or cold, tell your prescriber.

Injection-site reactions are a different matter and are covered in the leaflet. If you notice anything at the injection site, or a symptom you cannot explain, ask for a review. Aches and pains also get asked about, and we cover them in our guide to backache on Mounjaro.

Anyone can report a suspected side effect to the Yellow Card scheme, including patients and carers.¹⁹ You do not need to be certain that the medicine caused it. Reports are how safety information improves.

09 · Practical comfort

Practical ways to stay comfortable

While you work out the cause with your prescriber, simple measures cost little and carry no risk. Dress in layers so you can adjust easily. Keep warm drinks to hand, and keep up your fluids through the day. Eat regular meals with enough protein and variety, even when your appetite is small, and ask your prescriber if you struggle to eat well.

Keep your bedroom at a comfortable temperature and keep a regular sleep routine. If you are exercising more, which is part of treatment, warm up and cool down properly and change out of damp clothes afterwards.

These steps are general comfort advice, not treatment for any particular condition. If symptoms continue, get them checked rather than relying on self-care alone. Our weight loss clinic page explains the support available during treatment.

10 · Stopping and clearance

If you think of stopping

Speak to your prescriber before stopping Mounjaro because of chills. Tirzepatide has a half-life of about five days, so after a final dose it takes roughly four to five weeks to clear the system.¹ There is no way to speed this up, and nothing needs doing while it clears.

That has a practical meaning. If a symptom were caused by the medicine, stopping would not make it vanish overnight. If it has another cause, stopping would not fix it at all. Either way, getting the cause identified matters more than reacting quickly.

Treatment works alongside a reduced-calorie diet and increased physical activity. In the SURMOUNT-1 trial, adults taking tirzepatide lost on average 15% of their body weight on 5mg, 19.5% on 10mg and 20.9% on 15mg over 72 weeks, compared with 3.1% with lifestyle changes alone. These are trial averages and individual results vary.² A decision to stop is worth making with your prescriber, with the full picture in front of you.

11 · About Mounjaro

What is tirzepatide?

Mounjaro is the brand name for tirzepatide, a once-weekly injectable prescription medicine made by Eli Lilly. In the UK it is licensed for weight management in adults and for type 2 diabetes. It comes as a pre-filled multi-dose pen (KwikPen) in six strengths: 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg.¹

Tirzepatide is the first treatment of its kind to activate two natural gut-hormone receptors at once: GIP and GLP-1. Together these help regulate appetite, slow how quickly the stomach empties, and improve the way the body responds to insulin.¹

It is a prescription-only medicine, supplied only after an online consultation reviewed by a GPhC-registered prescriber. Mounjaro is available on the NHS, but access is being phased in over several years. NICE recommends it for adults with a BMI of at least 35 plus at least one weight-related condition.⁴

12 · 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