Using Semaglutide: What Actually Happens, Week by Week

Step 1: Starting low, the first four weeks at 0.25 mg

The first pen you use contains 0.25 mg of semaglutide. That dose is not where the weight-loss work happens; its job is to let your digestive system adjust. Most people tolerate it well. You inject once a week, into the abdomen, thigh, or upper arm, rotating the site each time. The pre-filled Wegovy pen handles the mechanism, press, hold, done.

Timing matters less than consistency. Pick a day that suits your routine and keep to it. If you miss a dose by more than a few days, the right call is to contact your prescriber or check the Patient Information Leaflet rather than doubling up. Our guide to using Wegovy covers the injection process in detail for anyone who wants a step-by-step walkthrough.

Store pens in the fridge between 2°C and 8°C. Once in use, follow the storage guidance in the leaflet precisely, that document is the authoritative source, not any general advice online. The NHS semaglutide medicines page is a reliable starting point for patient-level information.

Step 2: Moving through the titration schedule

After four weeks at 0.25 mg, the prescriber-guided schedule steps up to 0.5 mg, then 1.0 mg, then 1.7 mg, each step roughly four weeks apart. The final standard maintenance dose is 2.4 mg, which is where the pivotal STEP 1 trial (68 weeks, semaglutide versus placebo in adults without diabetes) demonstrated an average weight reduction of around 15%. The MHRA subsequently approved a 7.2 mg maintenance dose, with a dedicated single-dose pen cleared in April 2026 for adults with a BMI of 30 or above, where trials reported roughly 20.7% average weight loss. Availability of specific dose formats is confirmed at consultation.

The titration is not optional or cosmetic, moving too fast increases the likelihood of nausea and vomiting, which is exactly what the schedule is designed to soften. Some people move more slowly through the steps on clinical advice. Your prescriber makes that call, not the schedule alone.

Side effects at each step follow a similar pattern: most noticeable in the first few days after the dose increase, then generally settling. Nausea, loose stools, constipation, burping and indigestion are the most commonly reported. Eating smaller portions and avoiding very fatty meals at meal times tends to help.

Step 3: Being on maintenance dose, what changes and what doesn't

Reaching maintenance means the dose is stable, but the clinical relationship continues. At nume, every repeat order is reviewed by a GPhC-registered prescriber before it is dispensed, a real clinician reads your update, not an automated queue. That review matters because bodies change: weight plateaus, tolerability shifts, other medications change.

On maintenance, most people find appetite is meaningfully reduced. The practical risk at this stage is not eating enough protein, which matters for preserving muscle alongside fat loss. Adequate hydration and a diet built around protein and fibre are worth discussing with your prescriber or a dietitian, the NHS Better Health resources are a practical place to start for lifestyle context.

Stopping semaglutide is also something worth thinking about before you need to. What happens when you stop Wegovy is a question our prescribers hear regularly, and the short answer is that weight can return without ongoing lifestyle support, a good reason to have that conversation early. You can also read about when stopping is clinically appropriate.

For a broader picture of how semaglutide compares to other licensed options, the semaglutide overview covers the full context, including the distinction between Wegovy (weight management) and Ozempic (type 2 diabetes), two medicines with the same active ingredient but different licences. These are not interchangeable for weight loss purposes. NICE's appraisal of semaglutide for weight management (TA875) sets out the clinical criteria in detail.

When to get medical help during treatment

Most side effects are mild and temporary. A few are not. Severe, persistent abdominal pain that radiates to the back (with or without vomiting) needs urgent medical attention and may indicate acute pancreatitis, which the MHRA highlighted in a Drug Safety Update in January 2026. Gallbladder problems, significant dehydration from prolonged vomiting or diarrhoea, and signs of an allergic reaction (swelling, breathing difficulty, rash) all warrant calling 111 or 999 depending on severity.

Suspected side effects can be reported at the MHRA's Yellow Card scheme, patients can report directly, not just clinicians. If you have questions between doses, our aftercare team is available seven days a week. The disadvantages of Wegovy page covers the side-effect picture more thoroughly for anyone doing full due diligence.

If you are considering treatment and want clinical assessment without a waiting list, speak to our prescribers, your consultation is free, and the same-day review is carried out by a named, GPhC-registered Independent Prescriber.