Mounjaro

Mounjaro can be used for body weight management or for the treatment of type 2 diabetes. Here we discuss its use in body weight loss and maintenance.

Can I buy Mounjaro online?

The Online Clinic can prescribe Mounjaro for patients wishing to lose weight. Please click on the button below to start the process of a free online consultation with one of our experienced GPs.

What is Mounjaro?

Mounjaro is used in the management of body weight. It is used alongside a reduced calorie diet as well as increased physical activity.

Adults with:

• an initial body mass index (BMI) of 30 kg/m² or higher (i.e., with obesity), or
• an initial BMI ranging from 27 kg/m² or higher up to 30 kg/m² (i.e., overweight) and they have one or more conditions related to their high body weight, such as high blood pressure, abnormal blood lipid levels, cardiovascular disease, prediabetes or type 2 diabetes, and breathing problems when sleeping (called obstructive sleep apnoea).

Mounjaro contains the active ingredient tirzepatide. Tirzepatide works by blocking the action of two hormones (known as GIP and GLP-1) that are secreted by the intestine when eating and drinking. The medicine reduces body weight by regulating the appetite so that the amount of food eaten is reduced, and by modifying the way in which the body uses fat so that less fat is deposited in fat cells. Appetite is suppressed by increasing the feeling of satiety (i.e., feeling full), decreasing the feeling of hunger, and by reducing food cravings.

How to use Mounjaro

Mounjaro is the name given to tirzepatide solution for injection in pre-filled pens. Mounjaro is available in strengths of 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg. The version of pens used in the UK contain 4 doses of the medication. The device is known as Kwikpen.

Mounjaro is started at a dose of 2.5 mg once each week for 4 weeks. The dose is then increased to 5 mg once each week. Your doctor at The Online Clinic will then decide if you need a higher dose. The dose is increased by 2.5 mg to the next dose level after 4 weeks. Thus, after 4 weeks at 5 mg the dose is increased to 7.5 mg, which after 4 weeks may be increased to 10 mg, and so on to a maximum of 15 mg.

Mounjaro should be used on the same day and at the same time each week. The day can be changed but only after 3 days or more since Mounjaro was last given; then, on the new day, continue to give the dose once each week. Three days is the minimum time between two doses.

This medicine can be used with or without food. However, it is important when starting treatment to drink plenty of fluids to prevent dehydration. Dehydration can occur due to transient side effects such as feeling sick, being sick, and diarrhoea.

Before using Mounjaro, read the instructions on how to use the pre-filled pen. The medicine is injected beneath the skin (i.e., subcutaneously) of your abdomen, upper leg or upper arm. The same body area can be used each week for the injection, but the injection site in that body area must be different. Needles are supplied with the device free of additional charge at The Online Clinic.

The clinic must be immediately informed if you use more Mounjaro than advised, as you may experience low blood glucose levels, nausea, and vomiting. However, if you forget to inject Mounjaro, then it depends on timing:

• If 4 days or less since your scheduled Mounjaro injection, use Mounjara as soon as you remember and continue on your usual scheduled injection day.
• If 4 days or more since your scheduled Mounjaro injection, do not have the missed dose. Continue on your usual scheduled injection day at your scheduled dose.

Talk to your doctor before stopping this medicine.

People with body weight issues who also have diabetes will need their blood glucose levels monitored if Mounjaro is used in addition to insulin or a sulphonylurea.

Mounjaro Effectiveness

Based on clinical trial data, Mounjaro appears to be highly effective as a weight loss agent. Over a 72 week period, the average weight loss of those at the higher doses was over 20%. This compared with a weight loss of 2.4% in the placebo control group.

Who can use Mounjaro?

Mounjaro is for adults (18 years of age or older). Women who are pregnant, may be pregnant, planning to have a baby, or breast feeding should not use Mounjaro as its effects on the unborn child, newborns, and infants are unknown. They should get advice from a doctor before using Mounjaro and use contraception if using Mounjaro. Women with obesity/overweight and using oral contraceptives should consider a barrier contraceptive method or change to a non-oral contraceptive method for 4 weeks after starting Mounjaro and for 4 weeks after every dose increase.

People who have an allergy to tirzepatide or any of the other constituents in the injection solution should not use Mounjaro. Before using Mounjaro, inform the prescribing doctor if you have a severe problem with digesting food or food staying in your stomach for longer than considered normal such as with gastroparesis; have an eye problem such as macular oedema or diabetic retinopathy; have ever had inflammation of the pancreas (pancreatitis); and/or you are using certain medicines known as sulphonylureas or insulin.

Inform your doctor about all your medicines (i.e., those taken currently, recently, and could be taken in the future).

Mounjaro side effects

Although uncommon or rare, some side effects of Mounjaro are serious and need immediate medical attention. These include acute pancreatitis (may cause continuous severe stomach and back pain), and severe allergic reactions (symptoms include rapid heartbeat, breathing problems, swelling of lips, tongue and/or throat, and difficulty swallowing).

It is very common for people to experience some non-serious side effects. Vomiting (goes away over time) and constipation are very common particularly when used for weight management. Nausea and diarrhoea usually occur when starting tirzepatide and also go away over time. It is worth knowing that hypoglycaemia (low blood sugar level) can occur with Mounjaro, but this generally occurs specifically in people with type 2 diabetes who are also using a medicine containing a sulphonylurea and/or insulin (symptoms may include headache, dizziness, weakness, feeling hungry, fast heartbeat, drowsiness, confusion, irritability, and sweating).

Common non-serious side effects reported by patients treated for weight management include low blood pressure, dizziness, stomach pain, stomach bloating, indigestion, acid reflux, heartburn, burping, flatulence, tiredness/fatigue, and hair loss. Some people have injection site reactions such as redness and itching.

Those side effects that occur but are uncommon when Mounjaro is used for weight management include rapid heartbeat, gallstones and gallbladder infections, and increases in blood calcitonin level (a hormone that helps control blood calcium level) and/or increased blood amylase levels (helps digest carbohydrates in the intestine).

Reviewed by: Dr Loraine Haslam MBBS, DRCOG, DFSRH, LoC SDI, LoC IUT, MRCGP
GMC registration number: 4524038
Date: 28 March 2024
Next review: 27 March 2026
All UK registered doctors can have their registration checked on
The Medical Register at the GMC website.

Information Leaflet

Source and further information

Download Mounjaro Patient Information Leaflet