Wegovy: how long does it take to work?

Simon Edward • 30 June 2025

How long does it take Wegovy to work? Learn when you'll start noticing effects and experiencing weight loss.

Wegovy is an injectable weight loss drug available on prescription to people living with obesity (with a BMI of 30 or greater). It uses the active ingredient semaglutide.

You take Wegovy once a week using a special injection pen. After 12 months of treatment – including diet and exercise changes – you can expect to lose around 15% of your total body weight.

That's the goal. But how long does it take to get there? And when can you expect to start seeing results?

Let's investigate.

How long does it take semaglutide to work?

There are a few ways to answer this question. In this guide, we look at each of them in turn.

How long does it take for semaglutide to suppress appetite? In other words, when will you start feeling the effects of your weekly Wegovy injections?
How long does it take to lose weight? Or, to put it another way, how long do you have to wait until you start seeing results?
How long does Wegovy last in the body? The science question – how long does semaglutide stick around in your system after you take it?

A quick note before we dive in: as with any drug, Wegovy affects everyone differently. Two people could take exactly the same dose and experience different side effects, different changes in appetite and different rates of weight loss.

For instance, when we say that Wegovy users typically lose 15% of their body weight, we're referring to average weight loss. You might lose exactly 15% – but most lose a little more or a little less.

Got all that? Good. Let's start by looking at how long it takes for the effects of Wegovy to kick in.

How long does it take for semaglutide to suppress appetite?

Wegovy has several effects that help with weight loss. One of the most important is appetite suppression.

Wegovy slows down digestion and stomach emptying, which makes us feel fuller for longer. That means you're more likely to feel satisfied after eating smaller portions – and less likely to be tempted by snacks between meals.

The good news is that most Wegovy users start feeling these effects almost immediately. Many feel fuller and experience fewer food cravings shortly after taking their first dose.

More good news: these positive effects become more pronounced as you increase your dose and your body gets used to the medication. Things are looking up – and you're just getting started!

If you don't feel the effects immediately, stay positive. As we say, Wegovy affects everyone differently. You might just need a few more doses before you start noticing these changes.

And don't be disheartened if the effects wear off after a few days. This is normal. See, semaglutide needs time to build up in your body. As you continue treatment, the effects should stick around for longer.

How long does it take to lose weight?

While most users feel the effects of Wegovy straight away, it typically takes longer to start seeing results.

Generally speaking, you can expect to wait around two to three months (eight to 12 doses) before you notice visible weight loss.

Picture of a person wearing a pair of jeans, holding them in a way to show weight loss.

You won't spot anything earth-shattering at first. Perhaps you'll notice that your face looks a bit slimmer or that an old pair of jeans fits a little better. But these small gains feel like big rewards – and they're a good indicator that the treatment is working. Stick with it and you should see the results ramp up.

As for invisible results – well, that's a different story. Many users start losing a few pounds within the first month of treatment.

You'll only notice these initial results when you step on the scales. That's one reason it's a good idea to weigh yourself regularly as you continue treatment. Not only can it help you monitor weight loss, but it can also keep you motivated by bringing these invisible achievements to light.

Here's a month-by-month guide to average weight loss on Wegovy:

Months 1 and 2: you may lose a few pounds – but you probably won't notice much visible weight loss.
Months 3 and 4: this is where weight loss becomes noticeable for most people. By the end of month three, you should have lost around 6% of your starting body weight.
Months 4 and 5: by now, your weight loss efforts should show clearly on your face and waistline. After five months of treatment, most users experience weight loss of around 10%.
Month 6 onwards: if you've followed the standard treatment plan, you should now be on the maximum dose of Wegovy. On average, users see around 15% weight loss after six months.

Again, don't be disheartened if your own experiences are different. This is a typical weight loss journey on Wegovy – but it won't be the same for everyone.

Picture of a person doing light exercise.

And remember: it takes hard work to achieve lasting results. To make the most of Wegovy, you should take it alongside a healthy, balanced diet and increase your physical activity to help burn more calories.

How long does Wegovy last in the body?

Now for the science bit.

When scientists want to figure out how long a drug lasts in the body, they look at its half-life. Quite simply, this means 'the time it takes for the amount of a drug's active ingredient to reduce by half'.

Some drugs have short half-lives. You need to take these drugs regularly to make sure they stick around in your system. Examples include painkillers like ibuprofen and Aspirin.

Drugs with longer half-lives can be taken less regularly because they remain in the body for longer. The arthritis drug leflunomide, for instance, has a half-life of two weeks.³ This is considered a very long half-life.

Semaglutide has a fairly long half-life of one week. However, this doesn't mean all of the drug will be gone after two weeks. It actually takes between five and seven weeks for a single dose of Wegovy to disappear from the body.

By taking Wegovy once a week, you're letting the drug build up in your system. That's one reason why the effects of Wegovy get more pronounced with time.

Do you want to learn more about Wegovy? At SemaPen, we've created a series of expert guides that explain all the basics you need to know. Here's a selection to get you started:

Sources

1. Wilding, J.P.H. et al. (2021) "Once-weekly semaglutide in adults with overweight or obesity" The New England Journal of Medicine, 384(11) https://doi.org/10.1056/NEJMoa2032183

2. https://www.medicalnewstoday.com/articles/drug-half-life

3. Mamidala, R.K. et al. (2009) "Factors Influencing the Design and Performance of Oral Sustained/Controlled Release Dosage Forms" International Journal of Pharmaceutical Sciences and Nanotechnology, 2(3) http://dx.doi.org/10.37285/ijpsn.2009.2.3.1

4. Fornes, A. et al. (2022) "Once-Weekly Semaglutide for Weight Management: A Clinical Review" Journal of Pharmacy Technology, 38(4) https://doi.org/10.1177/87551225221092681

This article was reviewed and approved by Qutayba Almerie MD, MSc, FRCS on 14 July 2025.

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