Wegovy's 0.25mg starting dose: what the evidence says and what to expect

Why the clinical evidence supports a cautious starting point

The STEP 1 trial, published in the New England Journal of Medicine, enrolled 1,961 adults with obesity and demonstrated around 15% average body-weight reduction over 68 weeks at the 2.4mg maintenance dose. That headline figure is real. What the trial also recorded is that gastrointestinal events (nausea, vomiting, diarrhoea, constipation) were the most common reason participants dropped out or reduced their dose. The titration schedule, starting at 0.25mg, a dose designed specifically to let your gut adapt before the full pharmacological effect arrives, was specifically designed to limit that burden. Beginning at a sub-therapeutic level means your gut gets time to adapt to slower gastric emptying before the full pharmacological effect arrives.

The NHS semaglutide medicines page confirms this framing directly: 0.25mg is not a dose at which meaningful weight loss is expected. Its job is adjustment. Patients who try to skip it or push through a faster increase tend to experience worse nausea, which paradoxically makes the later, effective doses harder to tolerate.

Worth knowing: the STEP 1 trial allowed dose reductions for tolerability, evidence that even in a controlled research setting, the titration was treated as flexible within clinical judgement, not a rigid ladder everyone climbs at exactly the same rate.

What actually happens in the first four weeks on 0.25mg

For many people the first pen is unremarkable. Appetite may feel slightly reduced, but the change is subtle. Some notice mild nausea in the day or two after each injection, particularly in the first couple of weeks. Others feel very little at all. That range is normal and does not predict how well the medicine will work at higher doses.

Injection day matters too. Wegovy is a once-weekly subcutaneous injection, so you will be choosing a consistent day each week and rotating the injection site between the abdomen, thigh and upper arm. Practical tip from our prescribers: pick a day when you can take it easy for a few hours if nausea does arrive, at least for those early injections.

A question our prescribers hear most weeks is whether feeling almost nothing on 0.25mg means the medicine is not working or not genuine. It does not. The dose is intentionally below the level at which semaglutide produces its full GLP-1 receptor agonist effect on appetite regulation. Feeling well on it is a good sign, not a warning. The therapeutic work begins as the dose increases.

Storage matters from day one. Wegovy pens must be kept refrigerated at 2–8°C. The Patient Information Leaflet (not this page) is the authoritative source for your pen's specific room-temperature window if you need to take it out of the fridge briefly. Read it before your first injection.

When side effects appear and what warrants urgent attention

Nausea is the most reported side effect on Wegovy and is most likely in the first few weeks of a new dose. It typically settles within a few days to two weeks. Eating smaller meals, staying hydrated, and avoiding very fatty or rich food on injection day can help. Constipation and diarrhoea are also common; some people experience one and then the other as their GI system adapts.

Most of this is manageable and expected. What is not expected, and what requires prompt medical attention, is severe abdominal pain that does not pass, particularly pain that spreads to the back, with or without vomiting. This can be a sign of pancreatitis, which the MHRA flagged in a Drug Safety Update as an infrequent but serious risk with GLP-1 medicines. Gallbladder symptoms, signs of severe dehydration, and any allergic reaction also require you to stop and seek help. If in doubt, contact your prescriber or call 111. You can also report any suspected side effects through the MHRA Yellow Card scheme.

Under-18s are not licensed for Wegovy. The medicine is not recommended during pregnancy, while breastfeeding, or for anyone trying to conceive; if your situation changes, speak to your prescriber straight away.

Moving from 0.25mg to the next step (what the prescriber looks for

After four weeks on 0.25mg, the standard licensed pathway moves to 0.5mg, then roughly every four weeks upward through 1.0mg and 1.7mg toward the 2.4mg maintenance dose) or, where the 7.2mg single-dose pen is clinically appropriate, beyond that. The prescriber's decision at each step weighs up tolerability, any relevant medical history, and the evidence of how you are responding.

You can read more about how each dose compares across the full Wegovy dose range, including what the trial data shows at the higher levels. If you are moving to 0.5mg and want to know what changes, that page covers the pharmacological shift in detail. For a broader picture of what Wegovy involves as a treatment, the Wegovy overview is the place to start.

Private treatment costs vary by dose and provider. If you want context on what a full course realistically costs, the Wegovy prices page sets out what to expect and what a legitimate price should include. When you are ready to find out whether Wegovy is clinically suitable for you, start your free consultation with our prescribers.