Semaglutide 5mg: the dose that doesn't exist — and why that matters

The biggest misconception: that semaglutide comes in a 5mg strength

It's an understandable assumption. Tirzepatide (Mounjaro) comes in doses of 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg, and 15mg, so searching for a "5mg" pen feels reasonable. The confusion between the two medicines is genuinely common, our prescribers field versions of this question regularly. But semaglutide and tirzepatide are different molecules with different licensed dose ranges, and they are not interchangeable by dose number.

Wegovy's titration ladder, as described on the NHS semaglutide medicines page, runs: 0.25mg (weeks 1–4), 0.5mg (weeks 5–8), 1mg (weeks 9–12), 1.7mg (weeks 13–16), then 2.4mg as the standard maintenance dose from week 17 onwards. There is no 5mg rung anywhere in that sequence. If you've come across a "semaglutide 5mg pen" advertised online, that product has not been approved by the MHRA, and the MHRA has warned explicitly about counterfeit and unlicensed weight-loss pens circulating through social media and unverified online sellers, some of which have caused serious harm. The right response is not to buy it. You can report a suspect seller at the MHRA's Yellow Card scheme.

If you were actually looking for the 5mg tirzepatide dose, that's a different page entirely, tirzepatide is the active ingredient in Mounjaro, not Wegovy. The Wegovy overview and the full Wegovy dose guide set out exactly what's licensed and how the schedule works in practice.

What the licensed semaglutide doses actually do at each stage

The starting dose of 0.25mg isn't therapeutic in the weight-loss sense. Its job is to let your digestive system adjust to the medicine, nausea, reflux and stomach discomfort are most likely at that stage, and the low starting point keeps them manageable. Each four-week step upward adds to the appetite-suppressing effect as tolerance builds.

By the time most people reach 1mg or 1.7mg, they typically notice a meaningful reduction in hunger. The standard 2.4mg maintenance dose is where the clinical trial results were measured: in the STEP 1 trial, participants on semaglutide 2.4mg lost an average of around 15% of body weight over 68 weeks alongside lifestyle changes, published in the New England Journal of Medicine. The newer 7.2mg dose (approved by the MHRA on 14 April 2026 as a dedicated single-dose pen) is for adults with a BMI of 30 or above and reported around 20.7% average weight loss over 72 weeks in trials, narrowing the gap with tirzepatide at its highest dose.

Every step up the schedule is a prescriber's decision, not the patient's. If your tolerance is good, progression follows the standard timing. If side effects are disruptive, your prescriber may hold a dose for longer before moving up. For more detail on how the individual steps compare, the semaglutide dose guide covers each strength in context.

Who the licensed dose schedule actually suits

Wegovy is licensed in the UK for adults with a BMI of 30 or above, or a BMI of 27 to 29.9 alongside at least one weight-related condition such as high blood pressure, type 2 diabetes, or high cholesterol. Lower BMI thresholds apply for some ethnic backgrounds under UK guidance. Semaglutide is a Prescription-Only Medicine, so a prescriber reviews your medical history, current medications and circumstances before any treatment starts, the licence sets the eligibility framework, but it doesn't replace that individual assessment.

Wegovy is not the same medicine as Ozempic, even though both contain semaglutide. Ozempic is licensed for type 2 diabetes at doses up to 2mg and is not approved for weight management in its own right. People sometimes search for it as a weight-loss option, but that's a different licensing situation entirely. If you're weighing up what the treatment journey looks like in practice, including how costs compare across the schedule, the Wegovy pricing page sets out what private treatment typically involves.

For people who prefer not to inject, the MHRA approved Wegovy tablets in June 2026, the first oral GLP-1 medicine licensed for weight management in the UK. Those tablets use a different dose numbering (1.5mg, 4mg, 9mg, 25mg) entirely separate from the injection schedule. The weight-loss treatment overview covers both formats.

Side effects to know across the semaglutide schedule

The side-effect profile doesn't change much as doses increase, but intensity can tick up after each step, then settle over days to a couple of weeks. The most common effects are gastrointestinal: nausea, loose stools, constipation, indigestion, and burping. Fatigue and mild headaches are also reported at the start and after dose changes. These are well-documented and generally temporary.

A small number of people experience more serious effects. In January 2026 the MHRA issued guidance highlighting acute pancreatitis as a known but uncommon risk with GLP-1 medicines: severe stomach pain that spreads to the back, with or without vomiting, needs prompt medical attention rather than waiting for a routine appointment. Gallbladder problems, dehydration from persistent vomiting or diarrhoea, and signs of an allergic reaction are also reasons to contact a doctor promptly.

If you're already on a dose and have questions about what's normal vs. what needs attention, our prescribers are available seven days a week. You can also read the general FAQs or get in touch directly. If you're considering starting, compounded formats such as 2.5 mg/ml semaglutide may come up during your assessment, and the right first step is a clinical review, speaking to our prescribers is how that begins.