All major side effects taking weight loss drugs can have as people start taking them in 2026
They continue to grow in popularity, but some will experience side effects
We're officially into 2026 and weight loss drugs continue to go from strength to strength, as a growing number of people are using them to trim down their diets and their waistlines.
GLP-1 drugs such as Wegovy and Mounjaro can now be prescribed on the NHS in the UK to help people with weight loss, as long as they meet the criteria, but others are also buying jabs without a prescription.
While they use different ingredients, they work in basically the same way by triggering gut hormones which tell your brain you're full and don't need to eat any more, which means you would eat less and lose weight as a result.
Dr Giles Yeo told LADbible: "The good thing about the drugs is they're powerful. They work. They're broadly safe. The bad thing about these drugs is they're powerful, and they work for anyone."
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Of course, pretty much no drug comes without side effects, and people on these weight loss jabs have been documenting their experiences with them, and there are some major ones which have cropped up more than most.
Nausea
There are plenty of other side effects, and many people taking the weight loss jabs won't experience even the most common ones, but there are five signs which have been observed more often and among them is a feeling of nausea.
Some people who've taken the jabs have said they felt nauseous afterwards, though in some cases switching to a different kind of jab worked for them and their feelings cleared up.
Vomiting
A step up from feeling sick is actually being sick, and in more serious cases of side effects, this can happen.
You wouldn't be prescribed Ozempic for weight loss as it's a diabetes medication and isn't approved for weight loss, but people still try to take it for other things, and Stephen Fry said that he ended up being sick 'five times a day' from trying it.
He did say that it had the desired weight loss effect and thought it was 'brilliant' at first before he started to feel unwell.
Dr Yeo explained that people who were more likely to experience side effects were known as 'hyper-responders' and identifying them was part of research that goes into new drugs and medication.
Diarrhoea
Switching over to a rather brown note, one of the other major side effects people have experienced on weight loss drugs is diarrhoea.
Most people who have side effects will be experiencing some sort of gastrointestinal pain, and the more you take, the higher your risk of a side effect.
"The likelihood of these types of side-effects increases with higher doses," Dr Yeo told the Mail.
Constipation
If taking weight loss jabs is giving you gastrointestinal issues, then constipation is another one which is to be expected on the list.
You may be losing a significant amount of body fat over time on whichever drug you go with, but there are people who have felt like other parts of their belly and guts have changed as well.
There are other, rarer side effects, but your chances of getting those are rather slim, though, not nothing, and someone experiencing side effects can discuss them with medical professionals.
Abdominal pain
Rounding out the five main side effects of weight loss drugs is a feeling of pain in the abdomen.
Medical experts at Harvard suggest that if you want to reduce or try and avoid side effects while on weight loss drugs then you might try eating slowly and stopping when you feel full.
They also recommend smaller portions and not exercising immediately after eating.
Novo Nordisk, the manufacturer of Ozempic and Wegovy, told LADbible: "Patient safety is of the utmost importance to Novo Nordisk. We continuously collect safety data on our marketed GLP-1 RA medicines and work closely with the authorities to ensure patient safety. As part of this work we continue to monitor reports of adverse drug reactions through routine pharmacovigilance.
"GLP-1 receptor agonists (GLP-1 RAs) have been used to treat type 2 diabetes (T2D) for more than 15 years including Novo Nordisk GLP-1 RA products such as semaglutide and liraglutide that have been on the market for more than 10 years.
"We recommend patients take these medications for their approved indications and under the supervision of a healthcare professional. Treatment decisions should be made together with a healthcare provider who can evaluate the appropriateness of using a GLP-1 based on assessment of a patient’s individual medical profile.
"We recommend that any patient experiencing side effects while taking GLP receptor agonists including Wegovy®, Ozempic® or Rybelsus® report them to their healthcare provider and via the MHRA Yellow Card scheme: https://yellowcard.mhra.gov.uk/."
Eli Lilly, the manufacturer of Mounjaro, said: "Patient safety is Lilly’s top priority. We take any reports about patient safety seriously and actively monitor, evaluate, and report safety information for all our medicines.
"Mounjaro (tirzepatide) should only be used when prescribed by a healthcare professional and prescriptions should be fulfilled and supplied by registered pharmacies and providers."
Joe Harker