GLP-1 myths vs facts: What the evidence actually says

Most people who ask us about a GLP-1 myth have already spent weeks reading about it.

They have seen one video claiming the injections cause stomach paralysis, another claiming that GLP-1 medicines are basically free money for pharmaceutical companies, and a comment underneath from someone who says they lost five stone without changing a thing.

It is genuinely hard to work out what to trust.

Part of the problem is speed.

The GLP-1 medicines moved from specialist clinics to household conversation in about three years, which is faster than accurate information tends to travel.

Some of the scary headlines about these medicines are built on something real, just wildly out of proportion.

And also, a large unregulated market has grown up alongside the legitimate one, with a commercial interest in blurring the difference.

This guide is written to help you segregate facts from false claims. If you’re unsure about GLP-1 medications, this article will answer your questions, put your fears to rest, and help you get started on your weight loss journey.

If GLP-1 medications are new to you, start with our complete UK guide to GLP-1 medications and come back to this.

Before you begin: A little bit about OnlineClinic

OnlineClinic has been operating since 2011 and has treated more than 2.1 million patients.

The pharmacy is registered with the General Pharmaceutical Council (GPhC), our prescribers are registered with the General Medical Council (GMC), and the service is regulated by the Care Quality Commission (CQC).

As of August 2026, on Trustpilot, the service rating is 4.6 out of 5 based on 6,643 reviews.

Four developments this year have shifted several of these conversations, so they are worth knowing before you read on.

1. A falsified batch reached UK patients. In February 2026, the MHRA issued an alert about falsified Mounjaro KwikPen 15mg pens (batch D873576) supplied through one UK online pharmacy. The problem was spotted because the dose knobs were coming off during use.
2. A very rare eye risk was added to semaglutide's product information. On 5 February 2026, the MHRA updated the product information for Wegovy, Ozempic, and Rybelsus to include non-arteritic anterior ischaemic optic neuropathy (NAION), described as a very rare riskt.
3. Tablets arrived. An oral semaglutide tablet, called the Wegovy pill, for weight management was authorised in June 2026, and on 10 August 2026, the MHRA authorised orforglipron (brand name Foundayo), a once-daily GLP-1 tablet, making the UK the first country in Europe to do so.
4. A genetics study into pancreatitis is underway. The MHRA and Genomics England are recruiting through the Yellow Card Biobank to find out whether inherited factors explain why a small number of people develop acute pancreatitis on these medicines.

1. "Weight loss injections are the easy way out"

False
Nobody says a person with high blood pressure took the easy way out by using medication.

The commission's argument is that clinical obesity belongs in the same category: a long-term condition that responds to long-term treatment.

In January 2025, a global commission published in The Lancet Diabetes & Endocrinology redefined how obesity is diagnosed, separating "clinical obesity" (a chronic disease with measurable effects on how organs and tissues work) from "preclinical obesity" (excess body fat carrying future risk, but no current illness).

The commission involved 56 experts and has been endorsed by more than 75 medical organisations.

Its central point is that clinical obesity is a biologically driven medical condition, not a shortfall of motivation or discipline.

That matters here because appetite is not a matter of resolve.

It is a hormonal signal, and in some people, that signal is set unusually loud.

These medicines turn the volume down.

2. "Everyone is on Ozempic for weight loss"

False
At least not in the UK.

Ozempic and Wegovy contain the same active ingredient, semaglutide.

In this country, Ozempic is licensed for type 2 diabetes only, and Wegovy is the version licensed for weight management.

Prescribing Ozempic purely for weight loss is off-label, and it is not something we do at OnlineClinic.

If a pharmacy offers you Ozempic for weight loss, that tells you something useful about how it operates.

We unpick the licensing in full in Mounjaro vs Ozempic.

3. "You have to inject, so it is not for me"

False as of 2026
This is a genuinely new answer to an old question.

Needle anxiety is one of the most common reasons people stay away from GLP-1 medicines, and until recently, the honest answer was that injections were the only licensed option available for GLP-1-supported weight loss.

That changed twice this year.

An oral semaglutide tablet, called the Wegovy pill, was authorised for weight management by the MHRA in June 2026.

Then, on 10 August 2026, the MHRA authorised orforglipron (Foundayo), a once-daily tablet that works on the GLP-1 receptor but is built as a small molecule rather than a peptide, which means there are no food or water restrictions around taking it.

If injecting is your main hesitation, it is worth knowing the landscape is changing.

Our guide to the Wegovy pill and oral semaglutide tracks this.

4. "GLP-1 medications cause thyroid cancer"

Mostly false
With one real exception that has been true all along.

A Scandinavian cohort study published in The BMJ in 2024 followed GLP-1 users for a mean of 3.9 years and found no substantial increase in thyroid cancer risk.

A 2025 study compared 92,497 GLP-1 users with almost 2.5 million people taking a different diabetes medication across six national databases, and found no increased risk, with no signal at higher cumulative doses either.

The exception is specific rather than general.

A personal or family history of medullary thyroid carcinoma, or of multiple endocrine neoplasia (MEN) syndrome type 2, puts you at risk, so if you have either of these conditions, you might not be eligible for GLP-1 medications.

That is not a myth, it is a genuine contraindication, and it is one of the questions our prescriber asks before prescribing anything.

5. "GLP-1 medications cause depression and suicidal thoughts"

False
This one has been formally investigated twice.

Reports of psychiatric effects prompted reviews by both the European Medicines Agency and the MHRA.

The EMA's safety committee concluded in April 2024 that the available evidence did not support an association between GLP-1 medications and depression or suicidal thoughts.

The MHRA reached the same conclusion on 4 September 2024, stating that the evidence did not support a causal link between GLP-1 medicines and suicide, suicidal ideation, self-injury or depression.

Monitoring continues, as it does for any medicine still relatively new to wide use.

There is a fair reason the reports appeared.

Rates of depression are higher among people living with obesity to begin with, which makes a small number of reports difficult to interpret.

What we would say to any patient: If your mood shifts noticeably after starting treatment, tell your prescriber rather than assuming it is unrelated or that you have to push through.

6. "GLP-1 medicines paralyse your stomach"

Partly true
Slowing down how quickly your stomach empties is not a malfunction, it is part of how the medicines work.

That slowdown is why you feel full sooner and stay full longer, and it is also why nausea, reflux and constipation are the most common early complaints. The full timeline is in Mounjaro side effects week by week.

For most people this settles over the first month or two on each dose, and there are some practical fixes to implement: Smaller portions, low-fat meals, and adequate hydration.

Severe, persistent gastroparesis has been reported, and it is not nothing.

But it is rare, and it is not what the average patient experiences in week three.

If vomiting does not settle, or you cannot keep fluids down, contact your prescriber rather.

7. "Pancreatitis is common on these injections"

False
It is uncommon. It is also serious, which is why it gets more attention than its frequency alone would justify.

Acute pancreatitis is listed in the product information for these medicines, and the MHRA and Genomics England are now running a study through the Yellow Card Biobank to find out whether inherited genetic traits explain why a small number of people are affected while the great majority are not.

Patients hospitalised with acute pancreatitis within a year of starting a GLP-1 medicine are being invited to take part.

8. "GLP-1 medications can damage your eyesight"

True, with context

On 5 February 2026, the MHRA updated the product information for semaglutide medicines (Wegovy, Ozempic and Rybelsus) to include non-arteritic anterior ischaemic optic neuropathy, or NAION, described as a very rare occurrence.

NAION involves reduced blood flow to the front of the optic nerve and typically causes sudden, painless loss of vision in one eye, which patients often describe as blurring or cloudiness.

The European regulator had reached a similar conclusion in 2025.

"Very rare" is doing honest work in that sentence.

Published commentary on the UK decision noted only three Yellow Card reports up to August 2025.

The reason it was added anyway is that vision loss can be permanent, so the trade-off favours making sure patients know the symptom.

9. "You will lose 20% of your body weight on GLP-medications"

False

The trial figures that get quoted are averages on the highest doses.

In the SURMOUNT-1 trial, published in the New England Journal of Medicine, average weight loss over 72 weeks was 15.0% on 5mg of tirzepatide, 19.5% on 10mg and 20.9% on 15mg.

For semaglutide, the STEP-1 trial showed 14.9% weight loss at the 2.4mg dose, and the STEP UP trial of the newer 7.2mg dose reported 19% weight loss.

Some people lose considerably more weight than the trial average, some lose very little, and nobody can tell you in advance which group you are in.

Anyone promising you a number is selling, not prescribing.

What our prescribers can do is review your progress and adjust, which is what our Mounjaro plateau guide is about.

10. "GLP-1 medications eat away at your muscle"

Partly true
The missing context changes the conclusion.

In the body-composition substudy of SURMOUNT-1, 160 participants had DXA scans (X-Ray scans to measure bone mineral density) at the start and at week 72.

Body weight fell 21.3%, fat mass fell 33.9%, and lean mass fell 10.9%.

Roughly three-quarters of the weight lost was fat and a quarter was lean tissue.

The placebo group lost weight in almost exactly the same proportion.

Losing some lean tissue is what happens in any meaningful weight loss, not something the GLP-1 medication does uniquely.

Substudies of semaglutide have reported a higher lean fraction, though the trials were not designed to be compared head to head.

The useful part is that the proportion is not fixed.

Protein intake of at least 1.2 to 1.6g per kilogram of body weight per day, plus two or three resistance sessions a week, is what the evidence points to for protecting lean mass during weight loss.

You do not need a gym membership for that. We go into detail in Mounjaro and muscle loss.

11. "You do not need to change how you eat on GLP-1 medications"

False
Every pivotal trial behind these licences included a reduced-calorie diet and increased physical activity alongside the medication, and the UK authorisations are worded that way too.

The medication does not remove the need to eat well, it makes eating well possible, because the constant negotiation with hunger quietens down.

Patients often describe the first month on GLP-1 medications as the first time in years that a sensible portion felt like enough rather than a punishment.

Two things change.

Protein becomes a priority rather than an afterthought, because appetite is smaller and every meal has to count for more.

And very fatty or very large meals become genuinely uncomfortable rather than merely unwise.

12. "You regain weight the second you stop taking GLP-1 medications"

Partly true
The clearest evidence comes from the SURMOUNT-4 trial, published in JAMA. Participants took Mounjaro (tirzepatide) for 36 weeks (losing an average of 20.9%), then were randomly assigned either to continue or to switch to a placebo for a further 52 weeks.

Those who continued taking Mounjaro lost a further 5.5% weight.

Those who stopped taking Mounjaro or switched to a placebo regained an average of 14.0% of body weight.

Put another way, 89.5% of the people who continued the medicine held onto at least four-fifths of what they had lost, compared with 16.6% of those who stopped.

A later analysis in JAMA Internal Medicine looked at the people who had lost at least 10% weight and then came off treatment.

Most participants regained a substantial share of the weight they lost, and improvements in waist circumference, blood pressure, HbA1c and cholesterol drifted back in step with the weight.

So, weight regain is real.

What it is not is instant, total, or a reason to avoid starting.

It is the same pattern seen across obesity medications for more than two decades, which is why the trial authors describe obesity as a chronic condition needing long-term treatment.

Stopping well, with a plan, looks different from stopping abruptly, and we cover that in Stopping Mounjaro: What to expect.

13. "'Ozempic face' is a side effect of the drug"

False
It is a nickname for something much simpler.

When anyone loses a significant amount of weight quickly, some of it comes from the face, where fat pads sit close to the surface and their loss shows immediately.

The same change happens after major weight loss through any route.

It became attached to one brand name because that brand was in the headlines, not because the molecule does something to facial tissue.

What does seem to help is losing weight at a steadier pace, which means not rushing dose increases, and getting enough protein.

Both are worth raising with your prescriber if the pace of change is bothering you.

14. "A cheaper pen from a website is the same medicine"

False
In February 2026, the MHRA issued an alert about falsified Mounjaro KwikPen 15mg pens, batch D873576, that had been supplied through one UK online pharmacy.

The fault that exposed them was mechanical: Dose knobs coming off during use.

Because the regulator could not confirm the pens were sterile, they were not safe to use regardless of what was inside. The General Pharmaceutical Council served a notice of conditions on the pharmacy involved.

Further out from the regulated supply chain, it gets worse.

Independent laboratory testing of pens bought through social media has found a completely different active ingredient present at many times a normal starting dose.

There is no "generic Mounjaro" and there is no legitimate route that skips the prescription.

A related shortcut is worth naming: Splitting pens, decanting doses, or "microdosing" from a device designed to deliver fixed doses.

These pens are sealed, single-patient devices.

Once you are drawing from one with a syringe, both sterility and dose accuracy are guesswork. The MHRA's own advice on faulty pens is not to attempt to extract doses from them.

Quick tip: Three checks before you buy GLP-1 medication from anyone

• Is the pharmacy on the GPhC register? Registration is public and searchable. Ours is registered, and our prescribers are GMC-registered.
• Is there a real consultation with a named prescriber? "No consultation needed" is not a convenience, it is a sign the legal requirements are being skipped.
• Does the packaging match the product? Temperature-sensitive medication arriving in a plain envelope has not been stored properly. Do not use it.

If you think you have received a falsified or defective product, do not use it, and report it through the MHRA Yellow Card scheme.

Our pharmacy is GPhC-registered, the service is regulated by the Care Quality Commission, and if the prescriber decides treatment is not suitable for you they will tell you why.

You are not charged for treatment that is not issued.

15. "Berberine is nature's Ozempic"

False
Berberine is a plant alkaloid.

It does not act on the GLP-1 receptor, so the comparison is mechanistically wrong from the start.

Its better evidence sits around blood sugar rather than weight, and even those studies tend to be small and short.

The weight loss effect clinicians describe is measured in a few pounds, not the double-digit percentages seen with licensed medication.

There is also a live safety question.

In January 2026, the European Food Safety Authority's expert panel concluded that a safe intake level for berberine could not be established, citing concerns including genotoxicity and liver injury.

Because berberine is sold as a supplement rather than a medicine, the dose and purity in the bottle are not guaranteed to match the label.

If you are choosing between a supplement and a consultation, the consultation is free and the answer will at least be based on your medical history.

Our process is straightforward. From start to finish, this is what happens when you order with us:

1. Fill in the medical questionnaire. It takes 5 to 10 minutes. The questions are thorough on purpose.
2. A GMC-registered prescriber reviews your answers. If they need more details or want confirmation from the clinician managing your heart, they will message you through your account.
3. If treatment is approved, it is dispensed and dispatched. Next-day delivery, with needles, a sharps bin, and the full patient information leaflet included.
4. If it is not approved, the prescriber explains why. You are not charged for treatment that is not issued.

Our GLP-1 medication prices start at £69.99, and every price includes the prescription, the consultation, the packaging, and delivery. There are no hidden fees.

We prescribe GLP-1 for weight management following an online consultation.