Starting on a Wegovy 0.25 mg injection: what the first pen actually does

You've just been prescribed your first pen and you're wondering what it's actually for

Most people who pick up their first Wegovy pen expect to feel something dramatic in week one. A drop in hunger, perhaps, or a noticeable shift in appetite. For many, the 0.25 mg dose does produce some early reduction in cravings, but that isn't why it exists at this strength. Semaglutide is a GLP-1 receptor agonist, and when you first introduce it, your digestive system needs time to adapt to a slower gastric emptying rate. Nausea, burping, and loose stools are the most common early complaints, and they are considerably worse when people skip the 0.25 mg phase entirely and start higher.

The starting injection gives your gut four weeks to get used to how the medicine works before the dose climbs. Think of it as acclimatisation. The NHS patient information on semaglutide confirms this: if you want to read more about what Wegovy 0.25 is and why it is prescribed as an introductory dose, our dedicated page covers exactly that. That's normal, and expected.

Practically speaking: once you know which day you'll inject each week, many people find it helpful to keep the pen in the fridge door on that shelf they open every morning, a simple visual cue that the time is right. Storage must follow the SmPC exactly; the pen needs refrigeration at 2–8°C, and the precise room-temperature window if you're travelling should always come from the Patient Information Leaflet, not from online guides.

What the 0.25 mg pen looks like and how the injection actually works

Wegovy is supplied as a pre-filled injection pen. At 0.25 mg, the pen delivers a fixed subcutaneous dose, you inject just beneath the skin, not into muscle. The three approved injection sites are the abdomen (at least a few centimetres from the navel), the front of the thigh, and the outer upper arm. Rotating between sites each week reduces the chance of local skin reactions.

The needle used with the pen is short and fine; most people find the injection itself much less intimidating than they anticipated. If you want more detail on the specific pen format at this dose, this page on the 0.25 mg, 0.5 ml pen covers the physical device in more depth. Pinching the skin at the injection site before pressing the button is the standard technique; always follow the instructions in the leaflet packed with your pen.

After injection, the needle should be removed and disposed of in an approved sharps container. If you are unsure exactly how much 0.25 ml of Wegovy represents and what that means for your weekly dose, our page on the subject explains it clearly. Once you move to higher doses, the pen format may change, check with your prescriber or pharmacy at each titration step, since pen presentations can differ by strength. There is a separate guide to the full Wegovy dose schedule if you want to map out the road ahead.

Side effects at this dose: what's common, what to watch, and when to call for help

Gastrointestinal symptoms dominate the side-effect profile of semaglutide, especially early on. At 0.25 mg, most people experience them more mildly than at higher doses, which is the point of starting here. Nausea is the most frequently reported complaint, followed by constipation, diarrhoea, indigestion and fatigue. These typically ease after the first week or two as your body adapts, and they tend to return briefly whenever the dose steps up again.

Eating smaller meals, avoiding high-fat foods in the early weeks, and staying well hydrated all help. If vomiting or diarrhoea is severe enough to leave you unable to keep fluids down, that can lead to dehydration quickly, seek medical advice rather than waiting it out. Rare but serious signs to act on immediately include severe, persistent stomach pain that spreads to the back (which can indicate pancreatitis, a risk the MHRA specifically highlighted in a Drug Safety Update for GLP-1 medicines), signs of an allergic reaction, or sudden changes in vision.

You can report any suspected side effect through the MHRA Yellow Card scheme, which also allows you to flag suspect sellers. Pregnancy, breastfeeding, and trying to conceive are reasons Wegovy is not recommended, not licensed for under-18s either. If any of these situations change while you're on treatment, speak to your prescriber promptly.

Moving from 0.25 mg to the next step (and what a clinical review actually involves

After roughly four weeks on the 0.25 mg injection, the titration schedule moves to 0.5 mg, then 1.0 mg, then 1.7 mg, and eventually 2.4 mg as the standard maintenance dose) with 7.2 mg now approved as a higher option for eligible adults. Each step happens at roughly four-week intervals and is guided by clinical review, not a calendar alone. If side effects have been significant, your prescriber may suggest staying at 0.25 mg a little longer. That call belongs to them.

There's a detailed look at the step from 0.25 mg to 0.5 mg if you're approaching that transition and want to know what changes. For broader context on where the private route fits relative to NHS access (including which BMI thresholds apply) the weight-loss treatment overview sets that out clearly.

At nume, every repeat order is reviewed by a GPhC-registered prescriber before it goes out, a real clinician reads your notes, not software. The 0.25 mg pen is the beginning of a medically supervised journey, and getting those first four weeks right matters. If you have questions about whether Wegovy is clinically appropriate for you, the place to start is a free consultation with our clinical team.