How to Start Taking Wegovy: What to Expect in the First Weeks

Step 1: clinical assessment before the first dose

Wegovy cannot legally be dispensed in the UK without a prescription, and a prescriber needs to review your full picture before one is issued. At nume, that review is carried out the same day by a GPhC-registered Independent Prescriber, a real clinician who reads your answers, not automated software. They check your BMI, any existing health conditions, your current medicines and whether anything in your history makes semaglutide unsuitable. Only once that review clears does treatment move forward.

For most adults, the licensed eligibility criteria are a BMI of 30 or above, or 27 or above alongside a weight-related health condition such as high blood pressure, type 2 diabetes or high cholesterol. Lower BMI thresholds can apply for some ethnic backgrounds under UK guidance. BMI alone never settles it, the prescriber's clinical judgement is what matters.

If you're thinking about starting but aren't sure where you land on eligibility, the free consultation at nume is the practical first step.

Step 2: your first injection, and why it's set deliberately low

The first four weeks of Wegovy use a 0.25 mg dose. That's a small fraction of the 2.4 mg level that clinical trials used when measuring weight outcomes. The reason isn't caution for caution's sake: starting low and titrating slowly is how the prescribing schedule minimises gastrointestinal side effects. Many people find nausea is mild or absent at 0.25 mg; for others it's more noticeable in the first few days before settling.

You inject once a week, ideally on the same day each week, into the abdomen, thigh or upper arm. Rotating injection sites matters, injecting into the same spot repeatedly can cause tissue changes over time. Your Patient Information Leaflet details the exact technique; practical guidance on using the Wegovy pen covers the day-to-day habit. The pen is pre-filled, so there's no drawing-up of solution or fiddly calibration. One check worth doing before each injection: confirm the liquid in the pen window is clear and colourless. If it looks cloudy or contains particles, don't use that pen.

Store unused pens in the fridge (2–8°C). There is a limited window during which a pen can be kept at room temperature, the Patient Information Leaflet gives the exact timeframe, and that's the one to follow, not a number you've seen quoted online.

Step 3: the titration schedule, pacing the dose increases

After four weeks at 0.25 mg, the schedule moves to 0.5 mg, then 1.0 mg, 1.7 mg and finally 2.4 mg, with approximately four weeks at each level. In June 2026 the MHRA approved a higher 7.2 mg maintenance dose for eligible adults (BMI 30 or above); the titration to that level is managed by your prescriber and the same step-by-step principle applies. You can read more about the full Wegovy treatment overview, including the 7.2 mg approval, on our main Wegovy page.

Each dose increase tends to be when any gastrointestinal effects return briefly. Most people find they're manageable with some practical adjustments: eating smaller portions, choosing lower-fat foods and keeping well hydrated all reduce the likelihood of nausea. If an increase feels genuinely difficult, your prescriber can pause titration at the current level, this is a clinical conversation, not a failure.

The STEP 1 trial (68 weeks, published in the New England Journal of Medicine) found an average weight reduction of around 15% at 2.4 mg alongside lifestyle changes. That figure comes from reaching and staying at the maintenance dose, which is why the titration phase matters: it's the route to where the medicine does most of its work. If you want to understand the full process before your first pen arrives, our guide on how to start Wegovy walks through each stage in detail. Detailed context on what to expect from Wegovy for weight loss sits alongside this guide.

Step 4: what to watch for, and when to call for help

Common side effects are mostly gastrointestinal: nausea, loose stools, constipation, indigestion, burping and fatigue. They're at their most noticeable in the first week after starting or after a dose step-up, and they typically settle. Injection-site redness or itching is also reported and is generally mild.

Some symptoms need prompt medical attention. Severe stomach pain that spreads to your back (with or without vomiting) needs to be assessed urgently, as this can be a sign of pancreatitis. In January 2026 the MHRA reinforced that acute pancreatitis is a known, if uncommon, risk with GLP-1 medicines. Symptoms of a serious allergic reaction (swelling of the face or throat, difficulty breathing) or persistent vomiting leading to signs of dehydration are also reasons to seek help quickly, not wait for your next check-in.

For anything less urgent (questions about a dose, a missed injection, how a side effect is affecting you) our aftercare team is available seven days a week. The nume FAQs cover the questions that come up most in that first month. And if you're curious how starting Wegovy compares with starting tirzepatide, the semaglutide starting guide sits alongside a fuller comparison. On the question of cost, what Wegovy actually costs in the UK explains what's included in a legitimate private prescription price, a detail worth understanding before you begin.