Things to know when starting Wegovy — and what nobody warns you about

Why does Wegovy start at such a low dose, and when does it start working?

A question our prescribers hear regularly: if 2.4 mg is the maintenance dose, why begin at 0.25 mg? The first pen's job is adjustment, not treatment. Starting lower gives your gut time to adapt to the way semaglutide slows gastric emptying, which is exactly what causes most of the early nausea. Rushing to a higher dose tends to amplify side effects without meaningfully accelerating weight loss. The titration schedule runs 0.25 mg, 0.5 mg, 1.0 mg, 1.7 mg and finally 2.4 mg, with each step lasting roughly four weeks at your prescriber's direction.

Real weight loss usually becomes noticeable somewhere around weeks six to twelve, once you are further up the dose ladder and appetite suppression is properly established. Clinical trial averages (around 15% average body-weight reduction in the STEP 1 study, published in the New England Journal of Medicine) reflect outcomes at the 2.4 mg maintenance dose over 68 weeks. That is not a figure to expect at week four. If your progress feels slow early on, that is entirely normal. It also means your body is tolerating the medicine well, which is a good sign. For a broader look at how semaglutide works, our overview covers the mechanism in plain language.

One thing worth knowing before you start: NICE recommends reviewing whether to continue if weight loss is below 5% after six months on the maintenance dose, so there is a genuine clinical checkpoint built into the treatment pathway. Your prescriber will discuss this with you, and our page covering the key things to know about Wegovy is a good place to get across the broader picture before your first injection.

What side effects should you actually expect in the early weeks?

The most common experiences on Wegovy are gastrointestinal: nausea, loose stools, constipation, reflux and burping tend to cluster in the first few days after each new dose and, for most people, ease considerably within a week or two. Fatigue and mild headache are also reported, particularly early on. None of this is comfortable, but it is predictable, and it does improve.

Two things that do require prompt medical attention: first, severe stomach pain that travels through to your back, with or without vomiting, can be a sign of pancreatitis. In January 2026 the MHRA issued a Drug Safety Update specifically flagging acute pancreatitis as an infrequent but serious risk with GLP-1 medicines, and patients should seek urgent help if they experience it. You can report any suspected side effect directly through the Yellow Card scheme. Second, symptoms suggesting dehydration (dizziness, very little urine output, feeling faint) warrant the same urgency if they follow a bout of severe vomiting or diarrhoea.

Injection-site reactions are usually minor: brief stinging or a small red mark. Rotating sites between your abdomen, thigh and upper arm, as described in your Patient Information Leaflet, keeps reactions to a minimum. The NHS medicines page for semaglutide lists side effects in clear, patient-level language and is worth bookmarking before you inject for the first time.

Are there practical things about storage, timing and other medicines that first-time users miss?

Wegovy pens need to be kept refrigerated between 2°C and 8°C. They can be taken out of the fridge for a limited period at room temperature, but the exact window is set out in your Patient Information Leaflet, check it rather than guessing, because the figure matters. Pens should never be frozen. If you are travelling, a small medical cool bag is a straightforward solution.

Timing of your weekly injection is flexible, pick a day that suits your routine and stick with it. If you use oral contraceptives, tirzepatide (Mounjaro) carries a specific guidance note about pill absorption; semaglutide does not carry equivalent evidence of reduced pill effectiveness, though it is always worth mentioning all your medicines to your prescriber. The NHS England weight-management injections guidance covers the contraception and HRT considerations clearly.

If you are having surgery, tell both your surgical team and your anaesthetist that you take a GLP-1 medicine. Slower gastric emptying can affect anaesthesia safety. This is worth raising even for minor procedures. Our guide on what to know when starting Wegovy walks through these practical considerations in full, and anyone considering treatment can also read more on our pre-start checklist or explore the full picture on our Wegovy treatment page.

What does the prescription process actually look like, and who decides the dose?

We know a lot of people arriving here feel frustrated. Maybe you have been waiting months for an NHS referral, or you are not sure whether you even qualify. That uncertainty is understandable, and it is worth being direct about how the private route works.

Wegovy is a prescription-only medicine, which means a registered prescriber must assess you before any pen is dispensed. At nume, a GPhC-registered Independent Prescriber reads every consultation the same day, a real clinician, not an automated system. Identity is verified with photo ID, and weight is confirmed on a live video call. If you are approved, your first pen is dispatched the same working day for free next-working-day delivery through DPD, in plain packaging.

The prescriber decides your starting dose, reviews each repeat order and manages any dose changes. You do not self-titrate. Questions about affordability are common too, our page on how to manage the cost of Wegovy sets out what is included in the price and what to watch for when comparing providers. The full treatment overview lives at our weight-loss treatments overview if you want to compare options before committing. When you are ready to take the next step, you can start your free consultation with our clinical team.