How long until Wegovy works — and what does 'working' actually mean?

What happens in the first few weeks — before the scales shift?

The earliest changes on Wegovy are rarely about weight. They are about appetite. Semaglutide works by activating GLP-1 receptors in the brain and gut, slowing how quickly food leaves the stomach and signalling fullness earlier in a meal. That shift can register within days of the first injection, though it is subtle at 0.25 mg, the starting dose exists specifically to let your system adjust, not to deliver the full effect.

Many people describe week two or three as the moment it clicks: they leave food on the plate without thinking about it, or realise they forgot to eat lunch. That is the medicine doing its job at a low level. Actual body-weight reduction during weeks one to four is often modest (commonly one to two kilograms) and some people see nothing on the scales yet. That is normal. The earliest signs that Wegovy is starting to work are appetite-driven, not scale-driven.

Gastrointestinal side effects (nausea, loose stools, occasional burping) tend to be most noticeable in this opening phase, especially in the 24 to 48 hours after each injection. For most people they settle within a week or two and are less pronounced once the body adapts. The NHS medicines page on semaglutide lists these expected effects and is worth reading before your first pen arrives.

When does noticeable weight loss usually begin?

The honest answer: steadily, from around month two, and more clearly from month three. The dose is titrated upward roughly every four weeks, 0.25 mg, then 0.5 mg, then 1.0 mg, then 1.7 mg, reaching the 2.4 mg maintenance dose at around month four or five. Weight loss tends to accelerate at each new dose level before easing into a plateau, then picking up again.

By the 12-week mark, studies suggest most people on semaglutide have lost between 4% and 8% of their starting body weight. By six months, many are approaching 10%. The landmark STEP 1 trial, published in the New England Journal of Medicine, reported an average weight reduction of around 15% over 68 weeks at the 2.4 mg dose, meaningful results, but ones that accumulate over more than a year of treatment, not a few weeks. If progress feels slower than expected, it is worth reading about why weight loss on Wegovy can stall, as diet quality and activity levels both influence outcomes significantly.

One practical note: when your treatment is dispensed through a GPhC-registered pharmacy, the pen arrives via DPD in plain, unbranded packaging, you get a tracking notification and it is there the next working day. Knowing exactly when it lands means you can keep it refrigerated promptly, which matters for a temperature-sensitive medicine.

Does the timeline change if you're not losing weight by month three?

Possibly, and it is worth understanding why before drawing conclusions. Three months in, most people are still mid-titration, not yet at the full 2.4 mg dose. Comparing your month-three results against trial outcomes at 68 weeks is not a fair test of whether the medicine is working for you. The timeline for weight loss on Wegovy depends on the dose you have reached, what you are eating alongside it, and individual metabolic variation.

NICE guidance for semaglutide (TA875) suggests that if someone has not lost at least 5% of their starting weight after six months on the maintenance dose, continuing should be reviewed clinically. That review happens at the maintenance dose (2.4 mg) not at the intermediate steps. So if you are at month three and still on 1.0 mg, the clinical assessment point is still months away. Patience, combined with honest attention to diet and activity, is the right approach at that stage.

For context on what Wegovy costs if you are weighing up a private prescription route, the Wegovy pricing page sets out what a legitimate private prescription includes. What it should never be is a race to the cheapest listing, for a prescription medicine, the supply chain and clinical oversight matter more than the headline figure.

What does the full treatment arc look like?

Weight loss on Wegovy is a slow build. The first month is adjustment. Months two to four are where appetite suppression becomes reliable and the scales begin to move meaningfully. The six-month mark is often when patients feel the medicine has properly taken hold. Maximum average effect in the trials came at around 60 to 68 weeks, well over a year into treatment.

That timeline has clinical implications. Stopping treatment early, particularly at a dose increase plateau, often looks like failure when it is actually normal pharmacology. Our prescribers at nume's clinical team review progress at every repeat order, not just at the start, so if something is not working as expected, there is a clinical conversation to be had rather than a silent auto-renewal. You can read more about the full Wegovy treatment overview or explore other weight-loss treatment options if you are still deciding what fits your situation. When you are ready to talk it through with a prescriber, starting a free consultation takes a few minutes.