Ozempic, Mounjaro and Wegovy have been called miracle weight loss drugs. But for some people, the reality has been far from positive. Serious weight loss jab side effects — including stomach paralysis, gallbladder problems, and severe vomiting — are now being reported by users across the UK. If you’ve had a bad reaction to a weight loss injection, or want to understand the risks before starting treatment, this guide breaks down what you need to know.
The benefits and dangers of weight loss injections
Whether you’re considering weight loss injections, currently taking them, or dealing with complications after using one, this is your space to get informed – not just about the benefits, but about the very real risks.
So-called “weight loss injections” are hailed by celebrities, influencers, and even some doctors as a revolutionary tool in the fight against obesity.
Ozempic. Mounjaro. Wegovy. If you’ve spent more than five minutes on social media or scrolling headlines, you’ve probably heard of them. These drugs have become synonymous with rapid results – the kind of results that turn heads, spark conversation, and fill prescriptions at record speed.
But behind the headlines, the glossy before-and-after photos, and the TV interviews, lies a much more complicated story. Because while these jabs may work for some, for others, they’ve led to unexpected – and sometimes devastating – side effects.
From severe nausea to hospitalisation, people across the UK and beyond are speaking up about their experiences. Some were never warned. Some were never properly assessed. Some now live with the long-term consequences, and are seeking compensation via a class action lawsuit. In fact, as of April 1, 2025, there were 1,685 active lawsuits pending against pharmaceutical companies that sold GLP-1 drugs like Ozempic in the US.
And yet, public awareness remains limited. Warnings are often buried in small print, and stories of harm rarely go viral in the way transformation tales do.
Ozempic, Wegovy and Mounjaro were developed to help manage type 2 diabetes and, in some cases, clinical obesity. They’re part of a class of drugs known as GLP-1 receptor agonists (glucagon-like peptide-1).
In simple terms, they work by mimicking a natural hormone in the body that helps regulate blood sugar levels, slows down digestion, and reduces appetite. This is how they were originally used to help people with type 2 diabetes better control their blood sugar.
But something happened along the way.
Doctors and patients started noticing a powerful side effect: significant weight loss – sometimes more than 15% of a person’s body weight. It didn’t take long for this to catch on, and what started as a diabetes treatment quickly exploded into the wellness and weight loss space.
In 2023, Wegovy (a version of semaglutide, the same active ingredient in Ozempic) was officially approved in the UK for weight loss in certain cases. It was only meant for people with a high BMI (typically 30 or more) and with weight-related health conditions, like high blood pressure or sleep apnoea.
The idea was that specialists would prescribe it as part of a broader treatment plan involving diet, exercise, and lifestyle support. But in practice, things moved much faster. Suddenly, these injections were being advertised on social media, discussed on morning talk shows, and offered by online clinics and “medi-spas” (also known as med spas).
People who didn’t have diabetes or a high BMI were managing to access them, sometimes with very little medical oversight. And with that demand came a crucial shift: these drugs stopped being just about managing illness – and became a lifestyle trend.
Update: On 23rd June, 2025, prescriptions for Mounjaro jabs for weight loss, were made available at GP surgeries in England. Patients able to get the jab from their GP or a community clinic must have a BMI of 40 or over (or 37.5 if from a minority ethnic background), and four out of five weight related conditions ( type 2 diabetes, high blood pressure, heart and vascular disease, high cholesterol, or obstructive sleep apnoea).
Clinical trials have shown that medications like Wegovy and Mounjaro can lead to dramatic weight loss, especially when combined with changes to diet and physical activity. So, for many people, weight loss injections have delivered exactly what they promised.
In fact, it’s the success stories that have driven much of the excitement. From high-profile figures to everyday users, people have taken to social media and forums to share how these drugs helped them feel healthier, more confident, and finally in control of their eating habits.
Others credit the injections with giving them the energy to be more active, the confidence to return to work, or even the ability to come off other medications. For people living with type 2 diabetes or obesity-linked complications, these outcomes can be genuinely life-changing – even lifesaving.
It’s not hard to see why weight loss drugs have become so appealing, especially in a world where the pressure to lose weight can be overwhelming and traditional methods often fall short.
But the story doesn’t end there. Because alongside the positive outcomes, many people are now reporting severe, sometimes long-term, side effects.
Some of these were expected. Others were not. And in some cases, it’s not clear whether patients were properly warned about the risks before starting the treatment.
For people living with type 2 diabetes or obesity linked complications, these outcomes can be genuinely life-changing, even life-saving.
Common side effects for most people include nausea, mild digestive upset, headaches, and fatigue – especially in the early weeks. While these symptoms are usually temporary, they can still impact day-to-day life. Some users report needing time off work, missing social events, or struggling to maintain their usual routines.
According to the NHS and drug safety regulators, some of the most commonly reported side effects of GLP-1 medications include:
Most of these symptoms are considered mild to moderate and typically ease as the body adjusts. But even common side effects can significantly disrupt someone’s life – especially if they persist for weeks or interfere with eating and hydration.
This is why we need to look deeper into weight loss injections. Because understanding what can go wrong and why it’s happening is just as important as celebrating what goes right.
According to one user, weight loss injections left them feeling the worst they had ever felt in their life.
When people talk about weight loss injections, they usually mention the nausea. Maybe a bit of bloating. A few even say they lost their appetite completely, but in a way that felt manageable, almost welcome. What’s far less talked about is what happens when those symptoms don’t ease off or when they turn into something much more serious.
As prescriptions for weight loss jabs like Ozempic, Mounjaro, and Wegovy have surged, so too have reports of side effects that go far beyond mild discomfort. And in some cases, the people taking these injections have developed much more severe conditions. These include:
Gastroparesis is a rare but severe condition where the stomach muscles stop moving food effectively. Symptoms include chronic nausea, vomiting, bloating, and a feeling of being full after just a few bites. Gastroparesis can lead to hospitalisation and, in some cases, permanent dietary restrictions.
Pancreatitis is caused by an inflammation of the pancreas. This is a potentially life-threatening condition that causes intense abdominal pain, nausea, and vomiting.
Some users report gallstones or gallbladder inflammation, which may require surgery.
Severe dehydration caused by vomiting or diarrhoea may lead to kidney damage, especially in vulnerable users.
Stephen Fry, a well-known British actor, shared his experience with Ozempic, noting that he began vomiting up to five times daily, which led him to discontinue its use.
Studies show that many individuals regain a significant portion of their lost weight within a year of stopping Ozempic.
A small number of users have reported low mood, anxiety, or worsening of eating disorder symptoms. These links are still being studied, but they’ve raised important concerns - especially given how these drugs affect appetite and food behaviours.
The Medicines and Healthcare products Regulatory Agency (MHRA) has said weight-loss jabs may make the contraceptive pill less likely to work in those who are overweight or obese. It is not known whether taking medicines, such as Wegovy and Mounjaro, could harm an unborn baby.
Of course, most people who take these drugs do not experience severe complications. And some of these side effects remain under investigation and are not yet fully understood. But the problem is, many users say they weren’t properly warned about the risks. Others say they received their prescription after filling in a short online form or submitting photos, with no meaningful medical consultation or screening. Being told after the fact isn’t good enough when life-changing health implications are involved.
Behind every statistic, there’s a person. Someone who took a weight loss jab hoping for better health and instead found themselves in a struggle they never expected. Across the UK, more and more users are speaking up about what happened to them after taking Ozempic, Wegovy, or Mounjaro.
In late 2024, a nurse from North Lanarkshire tragically died after receiving just two low-dose tirzepatide (known as Mounjaro) injections. The official cause of death was listed as multiple organ failure, septic shock, and pancreatitis – with the medication recorded as a contributing factor. While this is believed to be the first fatality linked to weight loss injections in the UK, it has intensified scrutiny around how and to whom these drugs are being prescribed.
There are also reports that weight loss injections are being prescribed to people with eating disorders to help treat their conditions. Experts warn this is damaging already-vulnerable individuals and potentially exacerbating their illnesses.
When medications are classed as high-risk, we tend to picture strict controls: GP consultations, hospital prescriptions, and perhaps a team of specialists overseeing your care. And while that’s sometimes the case for weight loss injections like Wegovy, Ozempic, and Mounjaro, it’s far from the full picture. In reality, many people in the UK have managed to access these powerful drugs without ever speaking to a doctor face-to-face.
Scroll through Instagram, open TikTok, or type “Ozempic UK” into Google and you’ll find dozens of ads and clinics offering weight loss injections. Some operate through registered pharmacies. Others run cosmetic or “medi-spas.” Many rely on online forms, often asking a few basic questions about your weight, diet, and goals before issuing a prescription.
In theory, these platforms must still follow UK law. In practice, the level of medical assessment varies widely. Some people have reported receiving jabs after:
While this might feel convenient, it also increases the risk that patients aren’t being properly screened for:
In the UK, weight loss drugs fall under tight licensing controls. They are prescription-only medications that should only be dispensed after a thorough medical review.
The Medicines and Healthcare products Regulatory Agency (MHRA) and General Pharmaceutical Council (GPhC) have both issued guidance and warnings about the safe prescribing of GLP-1 drugs for weight loss. In response, stricter controls have come into force.
GLP-1 receptor agonists – including semaglutide (Ozempic/Wegovy) and tirzepatide (Mounjaro) – are now classed as high-risk drugs.
The General Pharmaceutical Council has introduced stricter guidance for online pharmacies, requiring:
The GPhC has also cracked down on online pharmacies processing vast volumes of prescriptions using automated systems, sometimes fulfilling quotas of dozens of weight loss jabs per hour – often without speaking to the patient.
The Medicines and Healthcare products Regulatory Agency (MHRA) has issued alerts reminding healthcare providers and patients of potential risks. In particular, they’ve highlighted:
These warnings are crucial, but not always visible to the average consumer, especially when flashy ads or influencer endorsements dominate the narrative.
Even with these new protections in place, problems persist:
In short, the rules are improving – but they’re not watertight. The system still relies heavily on proper prescribing and warnings, patients knowing the right questions to ask, understanding the risks upfront, and recognising when something isn’t right. And when those things don’t happen, the consequences can be serious.
Clear information, responsible prescribing, and stronger protections matter so much. Not least because, when something goes wrong, a lack of oversight becomes a serious risk to patient safety. However, as the prescribing rules tighten, some people are turning to unregulated suppliers to get their hands on the injections. This could involve buying medication from overseas websites, social media sellers, or backstreet clinics – with no idea what’s actually in the injection.
Aside from being illegal, this is incredibly dangerous. Some counterfeit products have been found to contain insulin or other unapproved substances, risking overdose, coma, or death.
If you’ve experienced unexpected side effects after taking a weight loss injection, whether it’s ongoing nausea or something more serious, you’re not alone. And more importantly, you’re not without options.
Here’s what you can do now to protect your health, get the support you need, and prepare for any next steps – whether that’s seeking medical treatment, reporting the issue, or claiming compensation.
Your first priority is your health. If you’re experiencing side effects, even if they seem mild, speak to a GP or pharmacist as soon as possible.
If you’re struggling to access care through your GP, you can also:
If something’s gone wrong, keeping a clear record can make all the difference later on. Whether you’re considering legal action or just want to understand what happened, having a personal timeline helps.
Make a note of:
You can keep this in a notebook, phone app, or digital document – whatever works best for you. Just make sure it’s updated regularly and stored safely.
If you’ve had side effects from a weight loss injection, even if you’ve recovered, you can report them to the UK’s Yellow Card scheme. This is the official system for tracking medicine safety, run by the MHRA.
Your report helps:
You don’t need a doctor to submit a Yellow Card. You can do it yourself, anonymously if you prefer.
Even if you’re not thinking about legal action right now, it’s still worth knowing where things stand. At the moment:
Right now, the best way to stay informed – and be ready if legal action launches – is to register with Join the Claim.
We’ll let you know:
This doesn’t mean you’re committing to anything. It just means you’ll be first to know if a group action is launched, and you won’t miss out on crucial developments.
If you’ve been affected by a weight loss injection and are wondering whether legal action might be possible, you’re not alone. While lawsuits in the UK haven’t officially started, what’s happening in the US is making people sit up and take notice. Because over there, the legal wheels are already in motion.
In mid-2024, the first major lawsuits were filed in the United States against manufacturers of GLP-1 medications.
The core of these legal claims is simple. Lawyers allege:
Legal experts in the US have estimated settlements could be worth hundreds of thousands of dollars per person for the most serious injuries. However, the process is still unfolding, and how manufacturers respond to these claims could shape the global conversation.
While the UK legal system is different from the US – and often slower to act – the foundations for similar claims already exist here. UK consumers have powerful protections under the Consumer Protection Act 1987, which allows people to seek compensation if a product is defective and causes harm.
It’s also worth noting that UK regulators have already begun tightening oversight – a clear sign that risks are being taken seriously.
In the UK, legal action wouldn’t necessarily stop at the drug manufacturers. Depending on the circumstances, it’s possible that:
…could face scrutiny if they failed to follow the rules or prescribed these drugs to people they shouldn’t have. For example, a pharmacy that issued weight loss jabs based on a short online form without checking your medical history could be held accountable if you suffered avoidable harm.
You don’t need to wait for a formal lawsuit to take action. Register your interest with Join the Claim to stay ahead of any legal developments.
It’s completely free to sign up, with no commitment. You’ll simply be kept informed, and if action becomes possible, you’ll know exactly what to do next.
While many people tolerate Ozempic well, some users have reported longer-term issues such as:
Gastroparesis (stomach paralysis)
Gallbladder problems
Pancreatitis
Kidney issues from dehydration
Ongoing digestive issues
Mental health concerns, including anxiety and disordered eating behaviours
Some of these risks are still being studied, but cases have already been reported across the UK. If symptoms don’t improve, or get worse, it’s important to get medical advice quickly.
Right now, there’s no group legal action in the UK, but that could change. In the US, lawsuits are already underway.
If it’s proven that drug companies or prescribers failed to warn people or acted irresponsibly, UK consumers may be able to seek compensation in future.
You can register with Join the Claim to be kept in the loop and know your options if mass legal action becomes possible.
In the meantime, you can always speak to a lawyer about starting an individual claim.
Gastroparesis (or stomach paralysis) is still considered rare. Symptoms include feeling full quickly, ongoing nausea, vomiting, and bloating. In some cases, it’s led to hospitalisation and long-term dietary restrictions. If you notice any of these signs, speak to a doctor straight away.
It depends on where you’re getting them from. Some online providers are fully licensed and follow strict guidelines. Others aren’t. We’ve heard reports of people who were given powerful drugs after filling in a short form or uploading a photo — no proper checks, no real consultation. That’s risky.
Yes, but only if the provider is properly regulated. In the UK, these drugs are prescription-only and classed as high-risk. That means there must be a full medical consultation and suitability check. If you didn’t have that, your provider may have broken the rules.
It’s the UK’s official system for reporting side effects from medications. Your report helps:
Keep people safe
Trigger investigations
Push for better warnings or restrictions
Weight loss injections have transformed lives, but they’ve also caused serious harm. That’s the uncomfortable truth we rarely hear in the headlines. Because the conversation about Ozempic, Wegovy and Mounjaro shouldn’t just be about celebrity transformations. It should also be about real people, people like you, who deserve to know the full story. And if your experience wasn’t what you were promised, you deserve to be heard.
If enough people speak up, we can push for answers, accountability, and maybe even change.
Bee is the content lead at Join the Claim, where she helps people understand their rights and take action when they’ve been wronged. With a background in PR, copywriting, and content strategy, she’s spent over a decade writing about legal matters – turning complex topics into clear, accessible resources that inform and empower.
From writing about data breaches to explaining how group claims work, Bee’s goal is always the same: to give people the confidence they need to take the next step. She’s committed to making legal information feel human, relevant, and easy to trust.
Disclaimer
This guide is for general information purposes only and does not provide medical or legal advice. While we aim to keep the content accurate and up to date, information about medicines, side effects, and legal developments may change over time.
Always speak to a qualified healthcare professional before starting or stopping any medication, including weight loss injections such as Ozempic, Wegovy or Mounjaro. If you are experiencing side effects, contact your GP, pharmacist or NHS 111.
If you are concerned about how you were prescribed a weight loss drug, or believe you have suffered harm, you may wish to seek independent legal advice. We do not accept any responsibility or liability for any loss, damage, or consequences resulting from actions taken based on the information provided.
Last Updated: 23 June 2025
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