Medication
How does Mounjaro work for weight loss?
How does Mounjaro work for weight loss?
Mounjaro reduces your appetite and helps you feel fuller for longer, helping you lose weight. Here’s the science behind how it works.

Medically reviewed by Dr Earim Chaudry
Chief Medical Officer
Benefits of Mounjaro
Mounjaro shows impressive weight loss results compared to lifestyle changes alone. The placebo group in the SURMOUNT-1 trial only lost 2.4% of their body weight in 72 weeks, compared to 16% for those on the lowest dose of Mounjaro.
Mounjaro also helps regulate your blood sugar levels, meaning your energy will be more balanced throughout the day and you won’t succumb to the same crashes and spikes. Finally, it reduces hunger and curbs cravings, quietening down any mental chatter around food.
Mounjaro side effects
Like any medication, Mounjaro comes with potential side effects, although in most cases these are short-lived, mild and manageable.
The most common side effects include:
- Gastrointestinal side effects (burping, flatulence, constipation, diarrhoea, nausea and vomiting)
- Mild weakness or fatigue
- Feelings of malaise
- Dizziness
- Hair loss
- Low blood pressure
- Injection site reactions like irritation, itching and bruising.
Most of the time, these side effects will subside as your body gets used to the medication.
Very rarely, users may experience more serious side effects including:
- Gallbladder disorders
- Very low blood sugar
- Pancreatitis
- Kidney disease
- Allergic reactions.
How to take Mounjaro
Mounjaro is taken as a once-weekly injection, using your pre-filled four-dose KwikPen. The Mounjaro should be injected into your upper leg, abdominal area or upper arm. You can opt for the same body part every time, but make sure to choose a different injection site within that area. Wash your hands before starting, then follow the ‘Instructions for Use’ to administer your dose.
Although it’s important to try to take Mounjaro on the same day every week, don’t worry too much if you miss a dose. You can take it as soon as you remember, so long as it’s within four days of your scheduled day. Any longer than that, and you should skip the dose.
Make sure to only take the dosage recommended by your doctor. Typically, you’ll start on 2.5mg a week for the first four weeks, before adjusting your dose in 2.5mg increments. If you accidentally take too much, speak to your doctor.
Is Mounjaro available on the NHS?
Mounjaro is not yet available on the NHS for weight loss, although the government has announced that it will soon begin a gradual rollout. It will initially be made available to people with a BMI over 40, along with three or more weight-related health problems. After that, it will be offered to other groups in priority order of clinical need.
In the meantime, Mounjaro can be accessed privately through clinics or weight loss management services like Voy. Voy combines clinically proven medication and lifestyle coaching to help you achieve weight loss that sticks.