Weight Loss Injections: How Do Drugs Like Vigovi and Monjaro Work?

Weight loss drugs will be offered to millions of people on the NHS, to help them manage their health.

One Jab, Vigovi, is already available to some and the other, Monjaro, will be available soon – although it may take more than a decade to fully launch.

Services are being stretched to cope with unprecedented demand from patients wanting to try weight-loss drugs, NHS experts have warned.

There are two drugs on the market – Semaglutide, sold under the brand name Wegovy, and tirzepatide, sold under the brand name Mounjaro. Semaglutide is also used in the diabetes treatment Ozempic.

Both Vigovi and Monjaro are given as weekly injections via a pre-filled pen that can be self-administered in the upper arm, thigh or abdomen.

They act as appetite suppressants by mimicking a hormone called glucagon-like peptide-1 (GLP-1).

This gut hormone is released after eating, and usually makes people feel full.

Monjaro also affects another hormone, glucose-dependent insulinotropic polypeptide (GIP), which affects metabolism and helps regulate energy balance.

Patients usually start on a low dose that is gradually increased until they reach a higher maintenance dose.

People taking these medications usually start losing weight within a few weeks.

Clinical trials show that – when combined with changes in their diet, exercise and behavior – users of Vigovi can lose more than 10% of their body weight after one year on treatment.

Other trials show that Monjaro users can lose even more. But it is difficult to compare the two treatments and, importantly, users of either can lose weight after stopping treatment.

At the moment, only Vigovi is available on the NHS in England, Wales and Scotland.

It must be prescribed by a weight management specialist, and access to them is limited.

To qualify, adults must be obese and have at least one pre-existing weight-related health condition such as high blood pressure.

People with heart disease who are overweight, but not obese, may also be prescribed medication.

According to NHS guidelines, patients must follow a diet and physical activity programme, and the drug should only be prescribed for a maximum of two years.

It is recommended by the National Institute for Health and Care Excellence (NICE). Monjaro should also be offered to NHS patients in England from March 2025.. This will be accompanied by diet and exercise advice.

As with Vigovi, it will initially only be available to obese patients with weight-related health conditions who are under the care of a specialist.

However, from June, the drug will be offered more widely. It is not clear how this will be managed, or who will provide ongoing monitoring and support.

Detailed NHS England guidance is expected in early 2025.

It is possible that around 3.4 million people could eventually qualify for Monjaro.

To help manage demand, Nice has said it could take more than a decade for the NHS to gain access to the drug. It is believed that 300,000 could benefit in the first three years.

In addition, the government has already announced plans to offer weight loss jobs to unemployed people living with obesity in England.

Prime Minister Sir Keir Starmer called the move May be “very important” to the economy and the health of individuals..

But weight loss experts have warned that NHS obesity services are already struggling to cope with demand for these drugs, and that injections should only be used as part of a wider treatment plan.

Both Vigovi and Monjaro can be bought privately, including in some supermarkets, chemists and high street clinics.

Pens usually cost between £200 and £300 depending on the dosage.

Drugs should not be bought from unregulated sources.

A BBC investigation in November 2023 found that online sellers were offering semaglutide as an over-the-counter medicine.

It also found the drug was being offered in beauty salons in Manchester and Liverpool.

The most common side effects are feeling sick, vomiting, bloating, constipation and diarrhea. Some people report hair loss.

Many side effects are manageable and go away over time. Others say they stopped taking drugs because of them.

In rare cases, serious side effects can include gallbladder and kidney problems and depression.

Experts warn that complications can be worse if the drug is misused, for example, taken as a quick fix to lose a few pounds or bought from unregulated online sellers.

Doctors say they have seen dangerous, life-threatening complications like pancreatitis in such cases.

That’s why experts say they should only be used under medical supervision.

Research suggests. People regain most of the weight within a year of stopping the drug, as their appetite returns to normal.

That is why experts recommend that patients improve their diet and increase the amount of exercise during treatment.

Health Secretary Wes Strating has warned that a “culture of dependency” could develop among people on these drugs.

There have been reports of Vigovi shortages in the past, although manufacturer Novo Nordisk says the NHS has a safe supply.

The term obesity describes a person who has excess body fat.

In the UK it is estimated that one in four adults is obese.

The standard way to classify people’s weight is to calculate their body mass index, or BMI, which means dividing an adult’s weight in kilograms by the square of their height in meters.

For most adults, if your BMI is:

• Below 18.5 – You are in the underweight range.
• 18.5 to 24.9 – You are in the healthy weight range.
• 25 to 29.9 – You are in the overweight range.
• 30 to 39.9 – You’re in the obese range.
• 40 or above – you are in the severely obese range.

People with an Asian, Chinese, Middle Eastern, Black African or Afro-Caribbean family background need to use a lower BMI score to measure overweight and obesity:

• 23 to 27.4 – overweight
• 27.5 or above – obesity

BMI has some limitations because it measures whether a person is carrying too much weight but not too much fat.

For example, people who are very muscular may have a high fat-free BMI.

But for most people, it’s a useful indicator of whether they’re at a healthy weight.