Wegovy injections for weight loss: Side effects and benefits
The UK is one of the heaviest nations in Europe now with 63.8 per cent of the population overweight or obese, and one in four of those people are classed as obese, according to latest figures.
Unsurprisingly, against this backdrop, the launch of weight loss drugs, such as Wegovy, which work by reducing appetite and also cut the risk of a heart attack, has taken the world by storm.
A weekly injection licensed in the UK late last year, Wegovy has been predicted to make £20 billion in peak sales, which would make it the most successful drug in history.
“It’s definitely a clinically effective drug, not just for weight loss, but because it improves control of diabetes and lowers blood pressure,” says Dr Katherine McCullough, a consultant in diabetes and endocrinology at the Royal Surrey County Hospital and the Royal College of Physicians advisor on obesity.
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What is Wegovy?
Wegovy is the trade name for injections licensed for weight loss containing the active ingredient semaglutide (another product made by the same company called Ozempic contains the same ingredient, but it’s only licensed for Type 2 diabetes).
“Wegovy and Ozempic are exactly the same drug; they’re just branded differently and available in different strength doses. Both are weekly injections,” explains Dr McCullough.
“Semaglutide is part of a group of drugs known as glucagon-like peptide-1 (GLP-1) receptor agonists. It was originally developed to help regulate blood sugar in people with Type 2 diabetes and has been in use for around 15 years, but another of its effects is weight loss.”
People prescribed Wegovy use a pen device to inject subcutaneously (into fat in the stomach or thigh) once a week.
How does Wegovy work for weight loss?
Semaglutide mimics the effects of a gut hormone called GLP-1 released after eating which regulates appetite and signals a feeling of fullness. “Semaglutide acts on key appetite regulating centres in the brain to make you feel full and not want to eat any more ,” says Dr McCullough. “It also acts on the stomach so it doesn’t empty as quickly as normal, making you feel fuller for longer as if you’ve had a big meal when you’ve actually had a small amount. Ultimately, it works by being an appetite suppressant.”
Eligibility and access
Although available on the NHS since September 2023 after being approved by the National Institute for Health and Care Excellence (Nice) in March 2023, there are strict eligibility criteria for Wegovy.
According to Nice, semaglutide can be prescribed to people:
With a BMI of 35 and above or
With a BMI of 30 to 34.9 with at least one weight-related illness , including high blood pressure , raised cholesterol, pre diabetes and Type 2 diabetes or obstructive sleep apnoea,
Alongside a calorie-controlled diet and increased physical activity
With support from a tier 3/4 weight management service (most of which are in secondary care)
For a maximum of two years
How to get a Wegovy prescription on the NHS
“To be prescribed Wegovy on the NHS you need to meet the Nice criteria,” says Dr McCullough.”Your GP can’t write you an NHS prescription for it.”
The main issue with getting access to Wegovy on the NHS at the moment is that it can only be prescribed to patients who are being treated in tier 3 weight management centres (only 44 per cent of hospitals have these) and the waiting list for these at the moment is up to five years in some places ,” says Dr McCullough.
“Private clinics and some pharmacies are offering Wegovy, but supplies in the private sector are at times unreliable, particularly at certain doses.”
There are reports that some NHS weight management services have had to close their waiting lists because of the pressures. Cost to the NHS for Wegovy runs at £2,000 a year per patient.
Getting a Wegovy prescription privately
Private clinics and online pharmacies are also offering the injections on private prescriptions at around £170 to £200 for a month’s supply, although they have also been affected by supply issues.
“These services don’t need to follow Nice guidelines so can prescribe it for people with a lower BMI in the overweight category, as well as for people who are classed as obese category,” says Dr Luke Pratsides, a GP and the head of medical at the online clinic Numan, which offers Wegovy and other weight loss drugs.
“Prescriptions are only made after an individual clinical safety assessment in compliance with regulations set by the Medicine and Healthcare products Regulatory Agency (MHRA).
“Clinics like ours also offer weight management support, giving nutritional and lifestyle advice, but some online pharmacies who sell it don’t.
“If you are choosing a private clinic look for one that has been inspected by the Care Quality Commission for safety, and if you are buying from a pharmacy make sure it is reputable. Look for the green cross symbol which indicates the pharmacy is registered with the General Pharmaceutical Council, the body that regulates pharmacies. There have been instances of some online sites selling fake versions of semaglutide so you should be vigilant on where you get your injections from.”
Benefits of Wegovy
These include weight loss, but also better blood sugar control and a lower risk of heart attack and stroke.
Weight loss
One study, published in the New England Journal of Medicine, found three quarters of people who received semaglutide in a 2.4 mg dose lost more than 10 per cent of their body weight. More than one third of trial participants lost over 20 per cent over 68 weeks. The average trial participants lost 15.3kg (3st).
Another study, which followed overweight patients who took semaglutide over two years, found they lost an average of 15.2 per cent of their body weight compared to 2.6 per cent in a placebo group.
“In my experience people tend to lose around 10 to 20 per cent of their body weight. Some will lose more, and the ones who tend to do the best are those who embrace diet and lifestyle changes alongside the injections,” says Dr McCullough. “It’s important to remember not everyone responds in the same way – some people do not lose much weight and there are also significant side effects to bear in mind.”
Other health benefits
Cuts the risk of heart attack and stroke: Semaglutide could also cut the risk of a heart attack or stroke by 20 per cent even if people lose less than 5 per cent of body weight. That’s according to unpublished findings from the Select trial presented at the European Congress of Obesity in May this year.
Better control of blood glucose in diabetes and pre-diabetes
Protective against kidney disease: One study in mice found liraglutide (another GLP-1 drug) could be protective for kidney function by reducing inflammation in the body
Side effects and considerations
Nausea
Vomiting
Constipation
Diarrhoea
Stomach pain
“The most common side effects are gastric ones, around a third of patients get these,” says Dr McCullough. “These usually settle down within a few weeks, so they don’t tend to persist but include nausea, vomiting, constipation, diarrhoea, and stomach pain.
‘“The most serious complication reported (and the rarest at less than 1 per cent) is pancreatitis (inflammation of the pancreas), which requires hospitalisation.”
Other rare side effects include:
Kidney problems (due to dehydration from vomiting)
Gallbladder problems such as gallstones
Animal studies have also suggested a possible link with medullary thyroid cancer, a rare type of cancer which runs in families
Safe dosage for Wegovy injections
Wegovy injections contain a 2.4 mg dose of semaglutide. “We tend to start patients on a low dose of 0.25 mg and work up towards a maintenance dose,” says Dr Pratsides. “We try to find the right dose for the individual within safe limits which is 2.4mg weekly.”
What happens after you stop taking Wegovy?
“The Step trial [which assessed the effectiveness of the injections against a placebo] found that approximately 60 per cent of people regain weight after they stop taking semaglutide, while 20 per cent of them regain all their weight,“ says Dr McCullough. “But on a positive note, more recent data suggests even after stopping the injections, when they followed them up a year later, about 20 per cent had managed to maintain their weight loss.
“What I say to patients is that the injections are a tool, use the time you are taking the medication to change your diet and physical activity and learn new healthy habits that will help you sustain your weight loss in the long term. That’s why it’s so important that people on the drugs receive support while they are on the injections and are not just given the drug and left to get on with it.”
Comparison with other weight management drugs
Wegovy isn’t the only weight loss drug around, there are dozens more in the pipeline and some already in use, including Saxenda and Mounjaro.
Here’s how they compare:
‘I’ve lost weight and had no side effects’
Mark Higgins, a 60-year-old biotech manager who lives with his wife Lucille, 54, in Surrey, has been taking Wegovy for a year. He has lost 20 per cent of his body weight dropping from 100 kg to 79 kg.
“I’d put on weight over a period of 15 years. I’m a bit of a stress eater and I travelled to the United States for work living in hotels and ate all the wrong things. I tried every diet, including the low carb and the 5:2, but I would just lose a few pounds and then put it on again. I decided to give weight loss injections a go after a spell of ill health, I wanted to get back in shape for health reasons. My dad was overweight and died at only 73.”
Mark began injecting himself once a week. “ I would open the fridge and not really fancy anything in it so I didn’t snack,’ says Mark. “I just didn’t eat as much.”
Side effects included nausea but this went away after a few weeks. His weight came off steadily every week. “It’s not quite a miracle drug, but it certainly delivers on the promise. It costs me £200 a month and I had to change clinics because of shortages, but I regard it as an investment in my health. I’ve been exercising more too, going to the gym regularly and swimming. I am worried about what will happen if I come off Wegovy, but am hoping some of my new healthier habits will help me keep the weight off. I suppose if I regain weight I can always go back on it.”
