This weekend, one of Ireland's most senior obesity doctors used the national broadcaster to deliver a blunt warning: hospitals are now seeing people made seriously ill by a weight-loss injection that is not approved for use anywhere in the world — and that some of them were given, twice a week, by their personal trainer at the gym.
The drug is called retatrutide — "reta" in the gym-floor shorthand — and the strange thing about this story is that the science behind it is genuinely impressive. That's exactly what makes the black-market version of it so dangerous. Here's what's actually going on, what the RTÉ report said, and what it means if you (or someone you train with) have been offered it.
What retatrutide actually is
Retatrutide is an injectable medicine being developed by Eli Lilly, the company behind Mounjaro. Where Mounjaro works on two gut-hormone receptors (GLP-1 and GIP), retatrutide works on three — GLP-1, GIP and glucagon — which is why it's often called a "triple agonist" and talked about as the next generation of weight-loss medication.
The trial results are real, and they're striking. In topline results reported by Eli Lilly from its first large Phase 3 trial (TRIUMPH-1), people on the highest dose lost an average of roughly 28% of their body weight over 80 weeks, and further Phase 3 readouts in 2026 have continued in the same direction. These are company-reported trial figures for a medicine still under investigation — not the performance of anything you can legally be prescribed.
And that's the crucial point: retatrutide has not been approved by any medicines regulator, anywhere. Not by the European Medicines Agency, not by the FDA, not by Ireland's HPRA. Eli Lilly doesn't even plan to submit it to the FDA for approval until early 2027. It cannot be legally sold in Ireland — or anywhere else — for human use.
What the RTÉ report described
According to the RTÉ News report (23 August 2026), Professor Donal O'Shea — a consultant endocrinologist and one of the country's leading obesity specialists — said retatrutide is being used in gyms on the advice of personal trainers, and described patients arriving in hospital unwell after using it — a drug bought through social media that has become popular with gym-goers who want to get leaner, faster.
He described one case from that very weekend: a patient who had been receiving retatrutide injections twice a week from their personal trainer at the gym, and who ended up in hospital with vomiting and kidney disease.
The report also carried a first-person account: an Irish online fitness coach told RTÉ she began using retatrutide in February ahead of a photoshoot, injecting twice a week. She described severe nausea within 30 minutes of each injection, eating fewer than 500 calories a day, and nearly collapsing in the gym before she stopped. It's a picture of exactly how this goes wrong — appetite suppressed far past the point of safety, with nobody medically responsible watching.
Three details from the report are worth sitting with:
- The supply chain is the gym floor. Personal trainers are recommending and administering an unapproved investigational drug — with no medical assessment, no dosing rationale, and no advice on side effects or what to do when they hit.
- The HPRA says this is growing. Ireland's medicines regulator described a "continual upward trend" in social media pages illegally selling weight-loss drugs.
- Patients are hiding it from their own doctors. Prof O'Shea said people are often too embarrassed to admit they're taking it — which leaves the medical team "blindfolded" when they arrive unwell. His plea was simple: if you're using one of these drugs and you're not feeling well, tell your doctor.
Eli Lilly itself has called on social media platforms to stop enabling the illegal market in its own investigational drug, and both Meta and TikTok say they've banned related content and hashtags. The trade continues anyway.
Why "it's basically the same as Mounjaro" is wrong
The pitch that sells black-market reta is that it's just a stronger version of the injections doctors already prescribe. That skips over two separate problems, either of which can put you in hospital.
1. The real drug isn't finished being tested
Approval isn't paperwork — it's the process that establishes safe dosing, who shouldn't take a medicine, and what needs monitoring. Retatrutide is still in that process. Its trials have reported gastrointestinal side effects (nausea, vomiting, diarrhoea, constipation), and the RTÉ report noted it can also affect the liver, pancreas and kidneys. Because the glucagon receptor is involved, retatrutide's profile is not simply "Mounjaro but more" — it's a different molecule whose safety picture is exactly what the ongoing Phase 3 programme exists to establish.
2. What's in the vial probably isn't the real drug anyway
Genuine retatrutide exists only inside Eli Lilly's clinical trials. Whatever is being sold on social media or the gym floor comes from unregulated laboratories — often labelled "for research purposes" to dodge medicines law. No regulator has checked what's in it, how concentrated it is, or whether it's sterile. You're trusting your kidneys to an anonymous seller's manufacturing standards.
The frustrating irony: regulated options already exist
What makes this story genuinely frustrating for doctors is that Ireland is not short of legitimate, licensed weight-loss medication. Mounjaro and Wegovy are both fully licensed in Europe, available in Ireland on prescription, and dispensed through regulated Irish pharmacies with medical supervision — dose titration, side-effect management, and a doctor who knows what you're taking.
The difference between that pathway and the gym-floor one isn't bureaucracy. It's everything the hospitalised patient in the RTÉ report didn't get: an assessment of whether the medicine suits them, a dose that follows the licence rather than a trainer's guess, and someone medically responsible to call when side effects start.
We've written a full guide to the risks of buying GLP-1s online without a prescription, and to what a proper medical weight-loss service should look like — the short version is that anyone selling you an injectable without a prescription, a doctor, and an Irish-registered pharmacy is breaking the law and gambling with your health.
See how the claim works →The doctor-led route, step by step
Online assessment
You share your health history, current medications, and goals through a structured medical review you complete from home. This is where suitability and safety are considered before anything else — a legitimate service will not skip it.
Clinician review and decision
A qualified clinician reviews your information remotely and decides whether a prescription treatment is appropriate for you. If it is not suitable, they should tell you that clearly — a genuine review can end in "no".
Regulated dispensing and delivery
If a treatment is prescribed, it is a licensed, manufacturer-sealed medicine dispensed through a regulated pharmacy — not an unlabelled vial. You should always know exactly what has been prescribed and why.
Remote check-ins and monitoring
Regular online follow-ups let a clinician review how you are getting on, discuss any side effects, and adjust the plan over time. Supervision is continuous, not a one-off — and it is the part unsafe routes tend to skip.
If you've already taken it
No lecture — just the message the hospital teams want you to hear: tell your doctor. Embarrassment is keeping people silent, and silence is what turns a manageable side effect into an emergency treated blind. If you're using any weight-loss drug from an unregulated source and you feel unwell — especially persistent vomiting, severe stomach pain, or a sudden drop in how much you're urinating — seek medical help and say exactly what you've taken and how often.
The bottom line
Retatrutide may well become an approved medicine in a few years — the trial data suggests it's a serious drug. But right now there is no legal, safe way to take it, and the versions circulating in Irish gyms and DMs are unregulated products of unknown composition, injected without any medical oversight. For people who are eligible, licensed medicines like Mounjaro and Wegovy already offer a legal, medically supervised route — with a doctor watching your back rather than a seller who disappears when side effects start.
Frequently asked questions
Is retatrutide legal in Ireland?
No. Retatrutide is not approved by the European Medicines Agency, the FDA, or any other regulator, and it cannot be legally sold for human use in Ireland or anywhere else. Products sold online as "reta" are unregulated and illegal to supply.
When will retatrutide be approved?
Eli Lilly has said it plans to submit retatrutide to the FDA in early 2027, and no European submission date has been announced. Even on an optimistic path, that means no legitimate access for some time — any product available today is not a licensed medicine.
Is retatrutide stronger than Mounjaro?
Trial results reported by Eli Lilly show larger average weight loss than has been seen with currently licensed medicines, but these are figures for a drug still under investigation — its full safety profile is precisely what the ongoing trials exist to establish. "Stronger" also means more to get wrong without medical supervision.
What should I do if I've been using black-market retatrutide?
Stop obtaining it from unregulated sources and tell your GP or treating doctor what you've taken, how much, and how often — even if you feel fine. If you feel unwell, particularly with persistent vomiting, severe abdominal pain or reduced urination, seek medical attention promptly and be candid about what you've used.
Are there legitimate alternatives available in Ireland?
Yes. Mounjaro and Wegovy are licensed for weight management in Europe and available in Ireland on prescription through regulated pharmacies, with medical supervision. Whether they're suitable for you is a decision for a doctor after a proper assessment — see our guide to weight-loss injection costs and providers in Ireland.
