What to Know Before Starting Wegovy: A Practical Guide

The first few weeks will feel different from what you expected

Picture this: your first Wegovy pen arrives on a Tuesday morning, plain box, DPD tracking pinged to your phone. You read the leaflet, inject at 0.25mg as instructed, and then wait for something dramatic to happen. It probably won't. That first dose (and the 0.5mg one that follows four weeks later) exists primarily to reduce the likelihood of nausea, not to produce meaningful weight loss. The titration schedule moves through 0.25mg, 0.5mg, 1mg, 1.7mg and 2.4mg over roughly sixteen weeks, with your prescriber guiding each step based on how you're tolerating it.

Many people find the dose increases are when they notice side effects most. Nausea, loose stools, constipation and indigestion tend to cluster around step-ups rather than running constantly throughout treatment. Eating smaller portions and avoiding high-fat meals can take the edge off. The NHS's patient information for semaglutide lays out what's common, what's uncommon and what warrants prompt medical attention, worth reading in full before your first injection rather than after. If you want to understand what typically happens in those first weeks and how to pace yourself, our page covering the things to know when starting Wegovy picks up where this one leaves off.

What you need to tell your prescriber before a pen is issued

A thorough medical history isn't a formality. Several conditions mean Wegovy may not be the right fit, or may need careful monitoring alongside it. A personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2 are contraindications. Pancreatitis (either past episodes or current symptoms) is another area the prescriber will probe: the MHRA issued a Drug Safety Update in January 2026 specifically flagging acute pancreatitis as an infrequent but serious risk with GLP-1 medicines, with severe persistent stomach pain that can radiate toward the back as the key warning sign.

Also worth raising: any surgery planned in the coming months (anaesthetists need to know about GLP-1 medicines before procedures), whether you take oral contraceptives, and whether you're on HRT. Unlike tirzepatide, current evidence does not suggest semaglutide meaningfully reduces oral contraceptive absorption, but your prescriber will want to assess your full medication list regardless. Pregnancy, breastfeeding or planning to conceive are situations where Wegovy is not recommended, and you'll need reliable contraception during treatment and for a wash-out period afterwards. If you want a thorough checklist of everything to consider before you begin, our guide on what to do before starting Wegovy covers the clinical and practical steps worth working through in advance. The NHS England guidance on weight-management injections gives a clear overview of the clinical considerations around contraception and surgery that apply to this class of medicines.

Who qualifies, and the difference between NHS and private routes

Wegovy's UK licence covers adults with a BMI of 30 or above, or 27 or above with at least one weight-related condition such as high blood pressure, high cholesterol, obstructive sleep apnoea or type 2 diabetes. Lower BMI thresholds apply for some ethnic backgrounds under UK clinical guidance. A higher BMI alone doesn't guarantee a prescription, a prescriber looks at the whole picture, including your current health, your medication list and your weight history.

On the NHS, NICE recommended semaglutide for use within specialist weight management services, for a maximum of two years, and with strict eligibility criteria. Waiting lists for those services can run to months or longer in some areas. Private prescribing through a regulated online pharmacy is the route for people who don't meet NHS criteria, who'd prefer not to wait, or who simply want to start sooner. If you're weighing up what getting started actually involves, our guide to where to buy Wegovy in the UK covers how to tell a legitimate pharmacy from one you should avoid. And if cost is a factor you're thinking through, the weight loss treatment overview gives honest context on how private treatment is typically priced.

Storage, injection technique and the practical habits that help

Wegovy pens need to be kept in the fridge between 2°C and 8°C until you use them, the medicine leaflet specifies a limited room-temperature window that you should follow exactly rather than estimate. Before the school run or first coffee of the morning isn't the ideal moment to rush an injection; many people find a set day and a set time each week makes the habit stick. You can inject into your abdomen, outer thigh or upper arm, rotating sites each time to avoid skin reactions building up.

If you miss a dose, your Patient Information Leaflet and prescriber are the right places to get guidance specific to how late you are, the advice differs depending on how long has passed. On the clinical side, protein intake and hydration become more important when appetite drops significantly, since the risk of losing muscle mass alongside fat is real. Our page covering the things to know about Wegovy covers longer-term habits worth building in from the start. For questions about your own situation, our support team is available seven days a week.