Wegovy 2.5mg: the starting dose explained

Step 1: why treatment opens at 2.5mg, not higher

Semaglutide slows how quickly the stomach empties and reduces appetite through GLP-1 receptor activity in the brain. Those effects can be abrupt if the dose climbs too fast, producing nausea, vomiting or dizziness that makes treatment hard to sustain. The 2.5mg weekly injection exists specifically to introduce semaglutide gently, giving the digestive system time to adapt before any meaningful therapeutic dose is reached.

This is why 2.5mg does not appear in the STEP 1 trial's weight-loss figures. That landmark New England Journal of Medicine study measured outcomes at the 2.4mg maintenance dose across 68 weeks, not at the starting phase. Expecting significant weight loss at 2.5mg misreads what the dose is for. The full Wegovy dose schedule runs from this 2.5mg opener through 5mg, 10mg, 17mg and up to 24mg weekly (expressed as 0.25mg, 0.5mg, 1mg, 1.7mg and 2.4mg in the standard semaglutide notation you'll see on prescriptions and packaging).

Practically speaking, what arrives at your door during this first month is the same pre-filled Wegovy pen (tracked by DPD, in plain unbranded packaging) just loaded with the starter concentration. The mechanism of injection is identical at every dose.

Step 2: what happens during the four weeks on 2.5mg

The 2.5mg period is primarily about tolerability, not the scales. Many people notice some appetite reduction even at this stage (that is the GLP-1 mechanism beginning to take effect) but significant weight change at this point is not the clinical aim, and its absence is not a sign the medicine is not working.

Side effects, if they occur, are most frequently gastrointestinal: mild nausea, loose stools or constipation, indigestion, or a feeling of fullness after small amounts of food. These are typically at their mildest during the 2.5mg phase precisely because the dose is low. The NHS semaglutide medicines page covers the full side-effect profile clearly, and our own guide to Wegovy 2.5mg side effects looks at what tends to happen specifically during this opener month.

Hydration matters more than many people expect at this stage. Reduced appetite can mean reduced fluid intake, which compounds any GI discomfort. Small, protein-rich meals tend to sit better than large ones. Your prescriber and the Patient Information Leaflet are the right sources for personal guidance here, these are general patterns, not instructions.

After four weeks, a prescriber reviews your experience before any move upward. That review is clinical, not automatic. If 2.5mg has been poorly tolerated, staying at this dose a little longer is a legitimate clinical choice.

Step 3: the prescriber review and what comes next

Moving from 2.5mg to the next rung on the schedule is not something that happens by default at the four-week mark. A prescriber looks at how the starting dose settled, checks for any concerns, and signs off the next step. This is true of every dose increase across the entire titration. At nume, that review is carried out by a GPhC-registered Independent Prescriber, not a triage algorithm, a real clinician reads your consultation before anything changes.

The question our prescribers hear regularly is whether staying at 2.5mg longer is safe. It is, but the dose was not designed as a long-term maintenance point. Weight loss in the context of Wegovy treatment is built at higher doses, and the starter month is the foundation, not the house.

For anyone who has read about the newer 7.2mg maximum dose approved by the MHRA in early 2026, that higher ceiling does not change how treatment starts. Every patient still opens at 2.5mg and works upward through clinical review. There are no shortcuts through the titration schedule, and a prescriber would not authorise them.

If you are considering where to access Wegovy through a regulated UK pharmacy, or want to understand the broader Wegovy treatment picture before starting, those pages cover both topics. The semaglutide 2.5mg dosing page goes further into the clinical mechanics of this specific phase. When you are ready to find out whether you are eligible, check your eligibility with our prescribers, the consultation is free, and a clinician reviews it the same day.