If you have heard about Mounjaro, Wegovy or the newer Wegovy pill and wondered what actually links them, the short answer is that they all belong to a family of medicines known as GLP-1 medications. Understanding what GLP-1 medications are — and how the class works — makes it much easier to follow the differences between the individual products.
This article is an impartial overview for UK readers. It is information only, not medical advice, and it does not recommend any product or supplier. Whether any of these medicines is suitable for you is a decision for a qualified prescriber.
What are GLP-1 medications?
GLP-1 stands for glucagon-like peptide-1, a hormone your gut releases naturally after you eat. GLP-1 medications — sometimes called GLP-1 receptor agonists — are laboratory-made molecules that mimic this hormone and switch on the same receptors in the body.
They were first developed to help manage type 2 diabetes, because GLP-1 helps the body release insulin when blood sugar rises. Over time it became clear that these medicines also reduce appetite and slow the stomach, which leads to meaningful weight loss. That dual usefulness is why the class has become so widely discussed.
In the UK, all of these medicines are prescription-only. They are licensed by the MHRA and, for some uses, assessed by NICE. You can read more about the individual products on our comparison page.
How the GLP-1 class works in the body
GLP-1 medications act in several overlapping ways:
- Appetite signalling in the brain. They act on areas that regulate hunger and fullness, so you tend to feel satisfied with less food.
- Slower stomach emptying. Food stays in the stomach a little longer, which prolongs the feeling of fullness after a meal.
- Blood-sugar control. They encourage insulin release when blood glucose is high and reduce the amount of sugar the liver produces, which is why they were first used in diabetes.
Because appetite falls, most people naturally eat fewer calories. The medicines are designed to work alongside changes to diet and physical activity, not instead of them.
What about the newer "dual" medicines?
Some of the most recent medicines do more than mimic GLP-1 alone. Tirzepatide (the active ingredient in Mounjaro) also acts on a second gut hormone receptor called GIP. This "twincretin" action is one reason it tends to produce larger average weight loss in trials than GLP-1-only medicines. The class is evolving quickly, and new agents are still being studied.
The main GLP-1 medications in the UK
Several products sit within this broad class. The ones most talked about for weight management are:
Mounjaro (tirzepatide)
A once-weekly injection that acts on both GLP-1 and GIP receptors. In the SURMOUNT-1 trial, average weight loss reached around 21–22% of body weight on the higher doses over 72 weeks. It is MHRA-licensed for weight management and recommended by NICE (TA1026), with a phased NHS rollout from 2025. More detail is on our Mounjaro page.
Wegovy (semaglutide injection)
A once-weekly GLP-1 injection. In the STEP 1 trial, the 2.4 mg dose produced average weight loss of about 15% over 68 weeks. On the NHS it is available through specialist weight-management services for a limited period, with wider access privately. See our Wegovy page.
The Wegovy pill (oral semaglutide)
Approved by the MHRA in June 2026, this is the UK's first oral GLP-1 weight-loss medicine — a daily tablet rather than an injection. In the OASIS 4 trial the 25 mg dose gave average weight loss of about 13.6% over 64 weeks. Learn more on our Wegovy pill page.
Foundayo (orforglipron)
A once-daily small-molecule GLP-1 tablet, authorised by the MHRA on 10 August 2026 for weight management and type 2 diabetes — the UK's second licensed GLP-1 pill. Unlike oral semaglutide it can be taken at any time of day, with or without food or water. It is currently available on private prescription only while NICE's appraisal is in progress. Details are on our Foundayo page.
Who might GLP-1 medications suit?
For weight management, UK private eligibility usually starts at a BMI of 30 or above, or 27 or above if you also have a weight-related condition such as high blood pressure, type 2 diabetes or sleep apnoea. NHS access is more restricted and varies by area and by product.
A prescriber will also check your medical history. These medicines are not suitable for everyone — for example during pregnancy or breastfeeding, or where there is a history of certain pancreatic or thyroid conditions. Only a GPhC-registered pharmacy or CQC-regulated clinic prescriber can decide whether treatment is appropriate for you.
How they are taken and adjusted
Most GLP-1 medications are started at a low "starter" dose and increased slowly over several weeks or months. This stepwise approach gives the body time to adjust and reduces side effects such as nausea. The injectable products are usually given once a week; the oral options are daily tablets. The dose that suits you is tailored by your prescriber and is not necessarily the maximum available.
Side effects and safety
The most common side effects across the class are digestive: nausea, diarrhoea, constipation and vomiting, especially in the early weeks or after a dose increase. These often settle over time.
Less commonly, more serious problems can occur, including pancreatitis (rare), gallstones and dehydration that can strain the kidneys. People also using insulin or a sulfonylurea may be at greater risk of low blood sugar. If you experience severe or persistent symptoms, seek medical advice.
A note on buying safely
Because these medicines are in high demand, they are sometimes offered by unregulated websites or as "compounded" copies. These can be unsafe, and their quality is not guaranteed. GLP-1 medications should only ever be obtained on a valid prescription from a UK-regulated pharmacy or clinic. This site does not name or recommend any seller; private prices vary between regulated providers, so compare carefully and check registration.
For more general questions, see our FAQ page or return to the homepage.
Frequently asked questions
What are GLP-1 medications in simple terms?
They are medicines that copy a natural gut hormone called GLP-1, which helps control appetite and blood sugar. By reducing hunger and slowing the stomach, they help people eat less and lose weight, alongside diet and activity changes.
Are all GLP-1 medications the same?
No. They share a common mechanism but differ in their active ingredient, how they are taken (weekly injection or daily tablet), average weight loss in trials, and licensing. Mounjaro also acts on a second hormone (GIP), not just GLP-1.
Can I get GLP-1 medications on the NHS?
Sometimes, but access is limited and varies by area and product. Wegovy is available through specialist weight-management services, and Mounjaro is being rolled out in phases from 2025, prioritising those with the highest need. Many people access them privately instead.
Do the side effects go away?
The common digestive side effects such as nausea often ease as the body adjusts, which is why doses are increased slowly. If symptoms are severe or persistent, speak to your prescriber, and report suspected side effects via the MHRA Yellow Card scheme.
Are compounded or online "copies" safe?
No. Compounded or unregulated versions are not quality-assured and can be dangerous. Only use a GLP-1 medicine prescribed by a UK-regulated pharmacy or clinic.
Is this article medical advice?
No. It is general information for UK readers. Whether any GLP-1 medicine is right for you is a decision for a qualified prescriber who knows your medical history.