How long after a Wegovy injection does it start working?

The first 72 hours: the medicine is working before you feel it

Your weekly Wegovy pen delivers semaglutide subcutaneously, into the fatty tissue of your abdomen, thigh, or upper arm. From there, absorption is slow by design. Blood levels rise gradually over roughly 24 to 48 hours, peaking around one to three days after the injection. At this point, semaglutide is binding to GLP-1 receptors in the gut and brain, slowing how quickly your stomach empties and beginning to modulate appetite signals in the hypothalamus.

Most people feel nothing dramatic in the first day or two. A subtle reduction in hunger is possible, particularly if you are sensitive to GLP-1 activity, but it is not the norm. If you are curious about how soon after injection Wegovy starts working, our dedicated page walks through the absorption timeline and what to realistically expect in those opening days. If you are curious about how quickly Wegovy starts working after injection, the short answer is that the medicine is present and active in your system by the time 72 hours have passed. The NHS semaglutide medicines page notes that Wegovy is taken once weekly precisely because semaglutide has a half-life of around seven days, keeping levels relatively steady between doses.

This is also the window when the starting dose, 0.25 mg, is doing its real job, not weight loss, but tolerability. The titration schedule exists to let your digestive system adjust before the therapeutic doses are introduced.

Weeks two to eight: appetite shifts, and so does the decision you face

For many people, the clearest early signal that Wegovy is working arrives somewhere between the second and fourth week: meals feel satisfying sooner, the pull toward snacking weakens, and the mental background noise around food quiets a little. These changes are modest at the lower doses but tend to sharpen as the prescription moves upward through the titration schedule.

Visible weight loss at this stage is typically small (a kilogram or two) and easy to doubt. This is the point where people often face a decision: is this working, or should I stop? The honest answer is that the 0.25 mg and 0.5 mg starting doses were never designed to produce large weight changes. They are tolerability steps. Expecting rapid results from them sets up unnecessary disappointment. Our Wegovy treatment overview covers the full titration pathway and what each stage is for.

Side effects are most likely to surface during dose increases. Nausea, loose stools, or an unsettled stomach are the most commonly reported; they tend to peak in the day or two after the injection and settle within the week. If you want a clearer picture of how long after injection Wegovy works and how that timing relates to when side effects appear, our guide to when semaglutide side effects start goes into that timing in more detail.

Month three to six: when most people see real results

The STEP 1 trial (published in the New England Journal of Medicine and involving nearly 2,000 adults) found an average weight reduction of around 15% at 68 weeks. That number accumulates slowly and unevenly. Most participants were approaching or at the 2.4 mg maintenance dose by weeks 16 to 20, and weight loss accelerated meaningfully from that point.

By the three-month mark on a stable dose, the majority of people on Wegovy have lost between 5% and 10% of their starting weight. By six months, those who respond well are often closer to 10–15%. The six-month point is clinically significant: under NICE guidance on semaglutide (TA875), if a person has not achieved at least 5% weight loss after six months at their highest tolerated dose, the prescriber should review whether continuing is the right path.

Factors that influence how quickly the medicine works include how closely dietary habits shift alongside it, activity levels, individual metabolic rate, and whether any underlying conditions affect response. Wegovy is licensed as an adjunct to a reduced-calorie diet and increased physical activity, neither alone drives results; both together do. A prescriber, not a set timeline, is best placed to assess your progress. If you have questions about how the journey looks from the outside, our clinical team page explains who reviews your treatment at each stage.

Beyond six months: staying the course and what to expect longer term

Weight loss on Wegovy is not linear. Many people plateau for a period, then resume losing, particularly after a dose increase. Others find their weight stabilises at a new set point before reaching 2.4 mg, which is a valid outcome if it reflects meaningful health improvement and is sustained. Wegovy under NICE's guidance is intended for use within a specialist weight management framework for a maximum of two years, though the private prescribing context differs and is managed case by case.

Stopping Wegovy typically leads to some weight regain over time, as semaglutide does not permanently alter appetite physiology. This is not a failure of willpower; it reflects how the medicine works. Decisions about continuing, pausing, or transitioning are between you and your prescriber, not something to judge from a results timeline alone.

If you are thinking about starting Wegovy through a regulated private route, you can read about how long after injecting Wegovy it works, including what to expect as levels build across the first few days, on our related page on early onset timing. And if you are ready to take the next step, speaking to a prescriber begins with a free consultation, no commitment required, reviewed the same day by a real clinician.