How long does 0.5mg Wegovy stay in your system?

What the evidence says about semaglutide's time in the body

Semaglutide's pharmacokinetic profile has been characterised thoroughly across the clinical trial programme. The STEP 1 trial, published in the New England Journal of Medicine, used weekly 2.4mg semaglutide and demonstrated that steady-state plasma concentrations are reached after approximately four to five weeks of consistent weekly dosing at any given dose level. This applies just as directly to the 0.5mg step as it does to the 2.4mg maintenance dose, the kinetics are the same; the concentration is simply lower.

With a half-life close to seven days, clearance follows a predictable arithmetic: after one week without a dose, roughly half the drug remains; after two weeks, about a quarter; after five weeks, concentrations have dropped to under 3% of their peak. In practical terms, 0.5mg Wegovy is largely cleared from the body within four to five weeks of a final injection, though trace amounts may persist slightly beyond that window.

That prolonged presence is by design. It keeps plasma levels steady enough for once-weekly dosing to work, avoiding the peaks and troughs of shorter-acting medicines. It also means the appetite-regulating effects of the 0.5mg dose don't switch off the day after a missed pen. What happens after stopping semaglutide entirely is a related question worth reading if you're considering pausing treatment.

Why 0.5mg is a step in the schedule, not the final destination

The 0.5mg dose sits within a structured titration sequence. Treatment opens at 0.25mg for the first four weeks (a period focused on tolerability, not meaningful weight loss) and 0.5mg follows for the next four weeks before the prescriber considers stepping up further. The full Wegovy dose range runs from 0.25mg through to 2.4mg as standard maintenance, with the newly licensed 7.2mg pen available at the top of the schedule for eligible patients.

Because steady state takes four to five weeks to establish, patients often notice the 0.5mg dose feeling more pronounced in weeks three and four than it did in week one. That isn't the dose changing; it's accumulated semaglutide reaching its plateau in plasma. Side effects follow a similar pattern, nausea, for example, can peak as concentrations build, then settle as the body adjusts. The NHS medicines page for semaglutide notes that gastrointestinal effects are most common around dose increases and the early weeks at a new level.

For those wanting to understand how other doses compare, the pharmacokinetics at 0.25mg and 1.7mg follow the same half-life logic, the clearance time is consistent; only the concentration differs.

Clinical situations where the 0.5mg clearance window matters most

Three clinical situations make the five-week washout particularly important to understand.

First, surgery. Anyone on semaglutide (including at the 0.5mg step) is advised to tell their anaesthetist and surgical team before any procedure. Delayed gastric emptying from GLP-1 medicines can affect anaesthetic risk, and NHS England guidance is explicit that your healthcare team should be informed ahead of any operation.

Second, contraception. For anyone taking the oral contraceptive pill, the interaction question is worth checking with your prescriber. Semaglutide's effect on gastric emptying may theoretically affect pill absorption, though the NHS guidance notes the evidence for this is less definitive for semaglutide than for tirzepatide. Worth discussing, not assuming.

Third, conception planning. Clinical guidance recommends stopping semaglutide before trying to conceive and allowing a washout period, given the five-week clearance time. Your prescriber will advise on the specific interval. Neither Wegovy nor any semaglutide-based medicine is recommended during pregnancy or breastfeeding.

If you're thinking about what the 0.5mg step means for the broader treatment journey, the Wegovy overview covers the full picture, how it works, the evidence behind it, and what to expect over time.

Storage, routine, and keeping the 0.5mg dose on track

A practical note that trips people up at this dose step: semaglutide pens require refrigeration between 2°C and 8°C, so keeping your pen in the fridge door (away from the back where temperatures can dip and the product can freeze) is worth making a habit from day one. Exactly how long a pen can safely sit at room temperature once removed is specific to the product leaflet, your Patient Information Leaflet carries the verified window, and that's the one to follow rather than any rule of thumb.

Consistency of dosing day matters more at 0.5mg than many patients expect, because the steady-state that makes this dose effective depends on reliable weekly intervals. A delayed injection by a day or two isn't automatically catastrophic (the long half-life provides some buffer) but drifting routinely will disrupt the plasma-level plateau. Any questions about a missed or delayed 0.5mg dose belong with your prescriber or the PIL; they're not a situation to navigate from general information alone.

Questions about the cost of continuing treatment through the titration steps are answered on the Wegovy prices page, where the full private pricing picture is set out clearly. If you're at 0.5mg and wondering whether treatment is right for you long-term, speaking to our prescribers is the clearest next step, consultations are free, clinically reviewed the same day, and there's no commitment required to ask a question.