How the Wegovy Weekly Injection Works: Timing, Technique and What to Expect

Why once a week, and does the day actually matter?

Semaglutide has a half-life of approximately one week, which is why the Wegovy weekly injection schedule works: the medicine stays active in your body between doses without needing daily top-ups. That long half-life also means the exact day is yours to choose, Monday, Saturday, whichever slots neatly into your routine. What matters is consistency. Shifting your injection day by a day or two occasionally is unlikely to cause problems, but a regular anchor day makes it easier to build the habit and easier for your prescriber to track your progress.

If you miss a dose and your next injection is more than three days away, you can take it as soon as you remember. If fewer than three days remain before your next scheduled dose, skip the missed one and continue from there. This is general guidance only, your Patient Information Leaflet and prescriber are the authority on missed doses for your specific situation, and the NHS semaglutide page sets out the standard missed-dose steps in plain language.

One practical note many people find helpful: pick an injection day that does not clash with a planned social event in the early weeks, when nausea after a dose increase is most likely. A Tuesday evening injection, for example, gives most of the first 24–48 hours at home. Small things like that make the early titration period more manageable.

Where do you inject Wegovy, and does the site make a difference?

The three licensed injection sites for the Wegovy injection pen are the abdomen (at least a couple of centimetres from the navel), the front or outer thigh, and the back of the upper arm. Rotating between these sites (and moving around within each site) helps prevent a build-up of fatty tissue under the skin, which can form if you use exactly the same spot repeatedly.

In clinical practice, the abdomen is the most commonly chosen site simply because it is easiest to reach yourself. The upper arm is perfectly valid if someone else is helping, or if you become confident with the angle. The site you choose does not meaningfully change how much semaglutide is absorbed, so comfort and rotation are the guiding principles. Clean the skin with an alcohol swab and let it dry before injecting; if you find clean prep materials useful, alcohol swabs are available separately should you need to restock.

Used pens contain a needle and must go into a sharps bin, not a household bin. A 1-litre sharps container is the standard choice for a single-pen weekly routine and can be collected by your local council when full, the NHS provides advice on disposal routes.

What should you expect during the first few months of injections?

The titration schedule exists for a reason. Starting at 0.25 mg gives your digestive system time to adjust to semaglutide before the therapeutic doses begin. Most people find that gastrointestinal side effects (nausea most commonly, but also loose stools, constipation, indigestion or burping) are most pronounced in the first week or two after a dose increase, then ease off. They tend to be mild to moderate and temporary for the majority of patients.

Appetite reduction usually becomes noticeable from around the 0.5 mg or 1.0 mg mark, though this varies. Some people notice it earlier; others feel little difference until they reach their maintenance dose. Eating smaller, lower-fat meals and staying well hydrated makes the adjustment more comfortable for most. Your prescriber can discuss practical strategies if side effects feel difficult to manage.

For detailed results evidence (including the STEP 1 trial data) and how Wegovy compares with tirzepatide, the Wegovy injection overview covers the clinical picture thoroughly. If you are also wondering whether Wegovy is a daily or weekly injection, our dedicated page answers that question alongside a breakdown of the dosing schedule. Information on how semaglutide works as a class is also on our semaglutide weekly injection page.

Are there situations where you should pause or seek help urgently?

Most people complete their Wegovy injections without serious problems. But there are symptoms that need prompt medical attention rather than a wait-and-see approach. Severe abdominal pain that persists and radiates toward the back (particularly with vomiting) should be assessed the same day; pancreatitis is a known but uncommon side effect of GLP-1 medicines, and the MHRA highlighted it specifically in a January 2026 Drug Safety Update. Symptoms of gallbladder problems (sharp pain in the upper right abdomen, fever, yellowing of the skin or eyes) also need same-day assessment. Dehydration from prolonged vomiting or diarrhoea is a more common reason to call a GP or 111.

If you are on oral contraceptives, note that semaglutide does not carry the same evidence of reduced pill absorption seen with tirzepatide, but speak to your prescriber about your contraception if you have any concerns. Wegovy is not recommended during pregnancy, while breastfeeding, or for anyone trying to conceive. It is not licensed for under-18s.

The cost and access side of treatment (including what a private prescription involves and what to expect from pricing) is covered on our weight-loss treatments page. Storage is a topic in its own right: once a pen has been opened and used for its first dose, the storage rules change, and our Wegovy storage guide explains the exact windows clearly. If you are at the stage of thinking about whether to begin, more about how nume's clinical team works is on our about page.

If you would like to discuss whether Wegovy is appropriate for your circumstances, our prescribers review consultations the same working day. Speak to our prescribers through a free consultation, no referral, no waiting list.