The Wegovy 4mg Pen: Your Questions Answered

Why does the Wegovy schedule include a 4mg pen at all?

The titration schedule for Wegovy exists because semaglutide's most common side effects are gastrointestinal, and they are most noticeable when the dose rises. Starting low and moving up in stages gives the gut time to adapt. The full schedule runs 0.25mg for four weeks, then 0.5mg, then 1mg, then 1.7mg, before reaching the 2.4mg maintenance dose — each step lasting approximately four weeks. The 1mg pen sits in the middle of that ladder, and the doses either side of it (0.5mg and 1.7mg) form the gradual ramp your prescriber is managing.

The NHS patient information for semaglutide explains the titration rationale clearly: each step is designed to minimise the nausea, vomiting and stomach discomfort that tend to ease once the body has had a few weeks at a given dose. This is not a sign that treatment is not working; it is the schedule doing what it is supposed to do. If side effects at 1mg are difficult, your prescriber may hold that dose for longer rather than moving up. That decision belongs with the clinician, not the calendar.

It is also worth being clear that the 4mg pen, in the context of the Wegovy schedule, refers to a pen labelled with its total cartridge content. Each pen delivers 1mg per injection across four weekly injections. The label wording can cause confusion, so checking what the volume and strength markings on your pen actually mean can save unnecessary worry.

What side effects are most common at the 1mg step, and when do they ease?

GI effects remain the dominant experience at this dose. Nausea is the most frequently reported, followed by loose stools, constipation, indigestion and burping. Fatigue and mild headache are also noted. These tend to be at their most noticeable in the first one to two weeks after a dose increase, then settle as the body adjusts. They do not usually mean treatment should stop, but they can be uncomfortable enough that people want reassurance.

Practical things that help: eating smaller portions, avoiding high-fat foods, staying well hydrated and giving the injection at a consistent time each week. Some people find evening injections suit them better if nausea peaks in the hours that follow. The guide on how to inject Wegovy correctly covers technique in detail, including rotating injection sites between the abdomen, thigh and upper arm to reduce site reactions.

Rare but serious symptoms require prompt medical attention. Severe, persistent stomach pain that radiates toward the back, with or without vomiting, should be assessed urgently — the MHRA issued a Drug Safety Update in January 2026 identifying acute pancreatitis as a known, infrequent but potentially serious risk with GLP-1 medicines. Report any suspected side effects at the MHRA's Yellow Card service.

Who is eligible for the 4mg pen and how does it fit into a full weight-management course?

Wegovy is licensed for adults with a BMI of 30 or above, or 27 to 29.9 with at least one weight-related condition such as high blood pressure, type 2 diabetes or high cholesterol. Lower BMI thresholds apply for people from South Asian, Chinese, Middle Eastern, Black African or African-Caribbean backgrounds under UK clinical guidance. No-one reaches the 4mg pen without already being on treatment; it is a continuation step, not a starting point, and requires ongoing clinical oversight at each stage.

Pregnancy, breastfeeding and actively trying to conceive are conditions under which semaglutide is not recommended. The medicine is not licensed for under-18s. The NHS semaglutide page sets out contraindications and special precautions in plain language and is worth reading alongside your patient information leaflet.

On the NHS, Wegovy is available through specialist weight management services under NICE guidance, with significant eligibility restrictions and waiting lists that can run long. Many people reach out to a private prescriber for that reason. If you are thinking about what private treatment involves, an overview of weight-loss treatment options is a practical place to start, and our free consultation is reviewed the same day by a real prescriber, not automated software.

How should the 4mg pen be stored, and what happens if a dose is missed?

Wegovy pens must be refrigerated at 2 to 8°C. If you are moving from the Wegovy 2mg pen to the next step in your titration, the same storage rules apply throughout the schedule. The pen you are currently using can be kept at room temperature for a limited period, but the exact window is set out in your patient information leaflet and on the SmPC, refer to those rather than to any third-party source, because the specifics matter. A practical habit that works for many people: keep the in-use pen in the fridge door so it is visible alongside everyday items and easy to retrieve at the same time each week.

If you miss an injection by less than five days from your usual day, take it as soon as you remember. If it has been more than five days, skip that week's dose and continue with your normal schedule the following week. Do not double up. For missed doses or anything that changes your injection timing, your patient information leaflet and your prescriber are the right sources, titration decisions, dose timing and what to do in unusual circumstances are not areas to navigate alone. If you have questions between appointments, our aftercare team is available seven days a week.