The things worth knowing about Wegovy before you begin

What the STEP 1 trial actually showed, and what it didn't

The STEP 1 results are often quoted as a headline figure, but the detail matters. At 68 weeks on the 2.4mg dose, participants lost around 15% of body weight on average. Those who completed the full course and stayed on treatment did somewhat better; the average includes people who reduced their dose or paused due to side effects. Crucially, the trial ran alongside a reduced-calorie diet and increased physical activity, semaglutide is an adjunct to lifestyle changes, not a replacement for them. The NHS medicines page for semaglutide frames it clearly: the medicine helps reduce appetite, but what you eat and how you move still shapes how much benefit you get.

A second thing the trial showed: weight tends to return when treatment stops, particularly without sustained lifestyle changes in place. That is not a criticism of the medicine; it reflects that obesity has biological drivers that need ongoing management. Your prescriber is the right person to discuss how long treatment should continue and what happens at the end of it.

More recently, a higher 7.2mg dose was approved by the MHRA, initially delivered as three 2.4mg pens weekly, then via a dedicated single-dose pen approved in April 2026. There are several things to know about Wegovy at this newer dose, including that trial data reported average weight loss of around 20.7% over 72 weeks, narrowing the gap with tirzepatide at its highest dose. Availability of specific doses is confirmed at consultation, not assumed in advance.

The side effects that catch people off guard

Most people starting Wegovy experience gastrointestinal effects at some point: nausea is the most common, followed by loose stools, constipation, vomiting, and reflux or indigestion. These tend to cluster around the first few days after an injection, especially following a dose increase, and often settle within a week or two. Eating smaller meals, going easy on fatty or spicy food, and staying well hydrated makes a meaningful difference for most people. You can find practical detail on what to avoid while on Wegovy to help manage these effects early on.

Less common but worth knowing: gallbladder problems can occur with rapid weight loss in general and specifically with GLP-1 medicines. In January 2026, the MHRA issued a Drug Safety Update highlighting acute pancreatitis as a known, infrequent but potentially serious effect of GLP-1 medicines, severe, persistent stomach pain that radiates to the back, with or without vomiting, warrants urgent medical attention rather than waiting to see if it passes. Report any suspected side effects to the MHRA via the Yellow Card scheme; this is how the regulator monitors real-world safety after approval.

One practical habit that takes under a minute: check the Wegovy pen before each weekly injection. The liquid should be clear and colourless. If it looks cloudy, discoloured or contains particles, do not use it, contact your pharmacy or prescriber. The Patient Information Leaflet that comes with your treatment describes this check, and it is the simplest quality step you can take yourself.

Who Wegovy is licensed for, and how NHS access actually works

The private prescription eligibility comes directly from the licensed indication: adults with a BMI of 30 or above, or 27 to 29.9 alongside at least one weight-related condition such as high blood pressure, raised cholesterol, type 2 diabetes or obstructive sleep apnoea. Lower BMI thresholds apply for some ethnic backgrounds under UK guidance. BMI is a starting point, not a decision in itself; a prescriber weighs up your medical history, current medicines and any contraindications before treatment is right for you. Pregnancy, breastfeeding and trying to conceive are all situations where Wegovy is not recommended, and the medicine is not licensed for anyone under 18.

On the NHS, NICE's appraisal of semaglutide (TA875) restricts access to specialist weight management services, with a maximum treatment duration of two years, for adults with a BMI of 35 or above and at least one comorbidity. NICE's published guidance on semaglutide sets out the full criteria; NHS waiting lists for specialist services are long in most areas. Private treatment through a regulated pharmacy is the practical alternative for people who meet the clinical criteria but are not in the NHS pathway, or do not want to wait. The cost of Wegovy privately varies by dose and provider; any legitimate price includes a prescription and clinical oversight.

Transferring to Wegovy or switching doses, what the evidence says

If you are already on treatment elsewhere and considering moving to a new provider, the clinical question is whether your current dose and response are properly documented. A prescriber needs to see evidence of your current treatment before continuing or adjusting it, that is a safety requirement, not a bureaucratic one. Starting Wegovy for the first time involves a different clinical assessment than transferring mid-course, and the two should be treated differently by any provider you use.

The titration schedule matters more than people often realise. Rushing through dose increases to reach 2.4mg faster does not improve outcomes and significantly increases the likelihood of severe nausea or vomiting. The stepped schedule (0.25mg, then 0.5mg, 1mg, 1.7mg, and finally 2.4mg, each held for roughly four weeks) exists because your gut needs time to adapt. Skipping steps is a decision for a prescriber, not something to self-manage. If you are curious about how the journey compares across the full semaglutide picture, the semaglutide overview covers the broader context. And if you want to understand what progress actually looks like week to week, our page on how to tell whether Wegovy is working covers the signals worth tracking. Our clinical team reviews every consultation individually, if you have questions specific to your situation, the right place to start is a free consultation rather than a forum.

Ready to find out whether Wegovy is the right fit for you? Start your free consultation and a GPhC-registered prescriber will review your details the same day.