Mounjaro weight loss jab: What you need to know as NHS changes prescription rules

Here’s how the drug works and who is eligible

GPs across England will, for the first time, be able to prescribe a new weight loss injection on the NHS from Monday, as the health service embarks on a significant mass rollout.

The medication, Mounjaro, is also known as tirzepatide and manufactured by Lilly.

It is expected to be made available to approximately 220,000 individuals identified as having the "greatest need" for treatment.

The drug was previously only accessible to patients through a specialist weight loss service or through private healthcare services.

This initial phase of the programme is projected to span the next three years, integrating the new drug into primary care.

Here is a look at Mounjaro and its effects.

GPs are now able to prescribe Mounjaro, or tirzepatide

How does tirzepatide work?

Tirzepatide, or Mounjaro, is an anti-diabetic drug.

It lowers which blood sugar levels and slows down how quickly food is digested. It makes those taking it feel fuller for longer – and therefore less hungry.

If the jab is recommended by a healthcare professional, those using it will need to eat a balanced, reduced-calorie diet and to exercise regularly while taking it, according to the NHS website.

Who might be eligible for the drug?

In the first year of the programme, the drug will be offered to people with a body mass index (BMI) score of more than 40 who have at least four other health problems linked to obesity, such as type 2 diabetes; high blood pressure; heart disease; and obstructive sleep apnoea.

It was previously only accessible to patients through a special weight loss service, to severely obese people who also suffer from a range of other health problems.

Estimates suggest around 1.5 million people in the UK are already taking weight loss drugs, which may have been prescribed through specialist weight loss services or via private prescription.

Mounjaro was originally developed as an anti-diabetic drug

How would it be administered?

The drug is usually delivered through a self-administered weekly injection which a doctor or nurse will show patients how to use, the NHS website says.

Who cannot take tirzepatide?

Mounjaro is not recommended for those who are pregnant or planning to get pregnant, breastfeeding or have certain health conditions, according to the NHS.

For those taking the contraceptive pill and using tirzepatide, the NHS recommends using an additional method of contraception, such as a condom, for the first four weeks of treatment and for four weeks after each dose increase as the contraceptive pill may not be absorbed by the body during this time.

What are the potential side effects?

Potential side effects of tirzepatide include nausea, vomiting, diarrhoea and constipation, according to the National Institute for Health and Care Excellence.