Mounjaro

How to use Mounjaro

Pick one day each week. Tirzepatide is injected once a week, at any time of day, with or without food. Pick a day that is easy to remember. You can change the day later as long as three days separate two doses.

Store pens in the fridge. Unused pens are kept in a refrigerator between 2 and 8 degrees Celsius, in the original carton so light cannot reach them, and must never be frozen. A pen that has been frozen must not be used.

Check the pen before use. Look at the liquid before you inject. It should be clear and free of particles or discolouration. Discard the pen if you can see anything floating in it, if it looks discoloured, or if it is out of date.

Inject into tummy, thigh or arm. Tirzepatide goes under the skin of the abdomen, the thigh or the upper arm. The back of the upper arm needs another person to do the injection. Read the instructions for use packed with the pen first.

Rotate the spot every week. Injection sites should be rotated with each dose, so the same patch of skin is not used week after week. If you also inject insulin, use a different site for each of the two medicines.

Missed dose: the four day rule. If you remember within four days, inject then and return to your usual schedule. If more than four days have passed, skip that dose and take the next one on the normal day. Never inject two doses to catch up.

Know how long a pen lasts. Single-dose pens and vials may be kept out of the refrigerator for up to 21 cumulative days below 30 degrees Celsius, then discarded. A multi-dose KwikPen holds four weekly doses and is thrown away 30 days after first use.

Keep the diet and activity going. Tirzepatide is licensed as an addition to a reduced-calorie diet and increased physical activity, not as a replacement for them. Every trial result quoted on this page comes from people doing both alongside the weekly injection.

Common side effects

Stop and get urgent medical help if (seek medical help immediately): Severe, persistent pain in the stomach area, with or without nausea and vomiting, which can signal pancreatitis, Breathing problems, or rapid swelling of the lips, tongue or throat, Difficulty swallowing together with a fast heartbeat, which can signal a severe allergic reaction, Vomiting or diarrhoea so severe or so lasting that you cannot keep fluids down, because dehydration can damage the kidneys, Pain in the upper right of the tummy with fever, or yellowing of the skin or eyes, Shakiness, sweating and confusion, if you also take insulin or a sulfonylurea for diabetes

Very common (very common (≥1/10)): Feeling sick (nausea), most often while the dose is being increased, Diarrhoea, usually mild or moderate, and easing over time, Vomiting; common rather than very common in type 2 diabetes, Constipation; common rather than very common in type 2 diabetes, Pain in the stomach area (abdomen); common rather than very common in type 2 diabetes

Common (common (≥1/100 to <1/10)): Indigestion, bloating, burping, wind or acid reflux, Tiredness, weakness or generally feeling unwell, Injection site reactions, most often redness and itching, Dizziness, or low blood pressure, A faster heart rate, Hair loss, Hypersensitivity reactions such as rash and dermatitis, Raised lipase or amylase on blood tests

Uncommon (uncommon (≥1/1,000 to <1/100)): Gallstones, or inflammation of the gallbladder (cholecystitis), Acute pancreatitis, which is inflammation of the pancreas, Pain at the injection site, Raised blood calcitonin, seen only on a blood test, Delayed stomach emptying

Rare (rare (≥1/10,000 to <1/1,000)): Anaphylactic reaction, a sudden and severe whole-body allergic reaction, Angioedema, deep swelling under the skin, often of the face or throat