Retatrutide: What to know about the new weight-loss medication

Retatrutide is the active ingredient in a new, once-weekly injection for weight loss and type 2 diabetes that is currently being developed. It is known as a triple hormone receptor agonist because it mimics the actions of the following 3 hormones that control appetite and blood glucose levels:

1. Glucagon-like peptide-1 (GLP-1).
2. Glucose-dependent insulinotropic polypeptide (GIP).
3. Glucagon.

Because of its ability to act on the receptors of these 3 hormones, it has a large effect on appetite and blood sugar management, and is expected to be more effective than other treatments, such as Wegovy and Mounjaro. However, retatrutide is still in the later stages of phase 3 clinical trials, so it’s not yet available to buy or on the NHS.

It is not yet known when retatrutide will be available in the UK, but it is unlikely to be available before 2027. That’s because it is still in phase 3 clinical trials, which are carried out to assess effectiveness in a large and diverse population. These trials are expected to be completed in May 2026.

The data from these trials will be used to support a potential application to the Food and Drug Administration (FDA) in the US, and potentially the Medicines and Healthcare products Regulatory Agency (MHRA) and National Institute for Health and Care Excellence (NICE) in the UK, in 2026 or 2027.

The approval stage can take several months or longer in some cases, and then manufacturers will need to start production, which may mean it takes another few months after this to reach the market.

Instead, there are several alternative weight loss medications available. At Asda Online Doctor, we offer a variety of injections and tablets, depending on your preference and suitability.

How much will retatrutide cost?

The cost of retatrutide is not yet known, but it is likely to be a similar price to its closest competitors, like Mounjaro and Wegovy. The price will be confirmed once retatrutide has been approved for use in the UK.

Retatrutide is a triple hormone receptor agonist, which means it mimics the actions of 3 hormones that reduce hunger, slow digestion, regulate blood sugar levels, and burn fat. The hormones it mimics are:

1. GLP-1 – stimulates the release of insulin, slows down the time it takes for food to pass through the stomach, and suppresses your appetite.
2. GIP – increases insulin release in response to lower blood sugar levels, plays a key role in fat metabolism, and limits desire for food intake.
3. Glucagon – increases the amount of energy and fat your body burns.

By binding to the receptors of these 3 hormones, retatrutide can reduce hunger, increase the number of calories your body burns, and lower your blood sugar levels to support sustainable weight loss.

Because retatrutide acts on these 3 hormones, it is also being referred to as “the triple G” in the media.

Like Wegovy and Mounjaro, retatrutide is a once-weekly subcutaneous injection, which means it is injected just under the skin of the upper arm, thigh, or stomach, rather than into a vein or muscle. The dosage schedule for retatrutide has not yet been finalised, but in clinical trials, participants have been given doses ranging from 1 to 12mg per week.

Participants have been started on a low retatrutide dose which has been gradually increased every 4 weeks to help reduce the chance of side effects. This is similar to other weight loss injections and how the Wegovy and Mounjaro dosage schedules currently work.

Retatrutide is only being developed in injection form at the moment, and no oral versions are available.

Instead, another GLP-1 agonist in the form of a daily tablet, orforglipron, is going through clinical testing and, if approved, is likely to be available in the UK in the future.

The side effects of retatrutide are similar to those of Wegovy and Mounjaro. The most commonly reported retatrutide side effects in clinical trials were mild to moderate gastrointestinal symptoms, such as:

• feeling sick (nausea)
• being sick (vomiting)
• diarrhoea
• constipation

These effects were more likely in people who were given higher retatrutide doses, and could be lessened by starting on a low dose and titrating up gradually.

Some people reported a dose-dependent increase in heart rate, with the increase peaking at week 24 before it started to come back down. However, this was not considered a safety concern and is similar to findings with other GLP-1 medications. For instance, an uncommon side effect of Mounjaro is a fast pulse, while an uncommon Wegovy side effect is a fast heartbeat.

Of those who received retatrutide, 7% experienced changes in skin sensation, such as tingling or sensitivity, but these were not reported to be severe and did not lead to anyone stopping treatment. This is also similar to other GLP-1 medications. A common, listed Wegovy side effect is changes in skin sensation, while this is listed as happening uncommonly in people taking Mounjaro.

Mounjaro is an effective and approved weight loss and type 2 diabetes medication in the UK, while retatrutide is currently going through clinical trials to investigate its effectiveness for weight management. Because retatrutide attaches to the receptors of 3 important hormones for appetite and blood sugar regulation, it could have a stronger effect than other weight loss medications, including Mounjaro.