How Long Does It Take for Semaglutide to Work?

Semaglutide is the active ingredient in the diabetes drugs Ozempic® and Rybelsus® and the weight loss drug Wegovy®. You can also get compounded semaglutide. Whatever you’re considering taking it for, it’s normal to wonder when you can expect the medication to kick in.

So, how long does it take for semaglutide to work? Unfortunately, there’s no solid answer to that. You might feel changes in your appetite within the first few days or weeks and notice weight loss and blood sugar changes within the first few weeks or months.

When does semaglutide start working? We’ll answer this tricky question below and share a timeline of how it might go down.

Semaglutide technically starts getting to work in the body straight away. It reaches maximum concentration one to three days after taking a dose.

You might start feeling some of the weight-loss-promoting effects within your first few days or weeks of treatment. These effects include:

• A reduced appetite

• Feeling fuller sooner and for longer

• Fewer cravings

• Less food noise

As for actual weight loss results, it can take a few weeks or longer, depending on how your body reacts.

How Long Does It Take for Semaglutide to Work in Clinical Trials?

A 2021 study funded by Novo Nordisk — the manufacturer of Ozempic, Wegovy, and Rybelsus — included almost 2,000 adults with excess weight or obesity (but not diabetes).

Participants took a weekly dose of Wegovy — 2.4 milligrams (mg) of semaglutide — or a placebo for 68 weeks. They also made healthy lifestyle changes, like eating a balanced diet with more nutritious foods and doing more movement.

By week four of the study, the participants taking Wegovy had lost weight. The four-week mark was the first check-in, though, so it’s unclear exactly when they started experiencing weight loss within that four-week window.

How long it takes semaglutide to work may vary depending on if you’re taking a different dose or type of the medication (injectables versus pills, for example). But this research suggests semaglutide can start working relatively fast when it comes to weight loss.

Don’t panic if you don’t notice changes right away. Weight loss is a slow and steady process, whether you’re taking semaglutide or not. That said, if you’re still hungry on semaglutide, check out our guide for tips.

Semaglutide Weight Loss Timeline

There’s no set weight loss timeline when taking semaglutide. Everyone reacts to the medication differently, and many factors affect how quickly semaglutide works.

If you’d like a rough idea of what to expect, though, the Wegovy study we mentioned above found that those taking a 2.4 mg dose of semaglutide lost about:

• Two percent of their body weight by week four

• Four percent of their body weight by week eight

• Six percent of their body weight by week 12

• 10 percent of their body weight by week 20

• 15 percent of their body weight in one year

Beyond the one-year mark, semaglutide can help you lose weight until you hit your goal weight — and then help with long-term weight management.

How long can you take semaglutide for weight loss? Our guide covers long-term use.

Your Semaglutide Options

FYI, semaglutide belongs to a class of medications called glucagon-like peptide-1 receptor agonists (or, less of a mouthful, GLP-1s). There are a few different semaglutide drugs.

Here’s a quick rundown:

• Ozempic. Ozempic is a weekly injection approved by the FDA (U.S. Food and Drug Administration) to treat type 2 diabetes. It’s sometimes prescribed off-label for weight loss.

• Rybelsus. Rybelsus is a daily pill FDA-approved for diabetes but sometimes prescribed off-label for weight loss.

• Wegovy. Wegovy is a weekly injection FDA-approved for those with excess weight and obesity.

• Compounded semaglutide. Compounded semaglutide isn’t FDA-approved. It's typically used for weight loss.

As with brand-name versions of semaglutide, there’s no magic number for how long compounded semaglutide takes to work. It depends on numerous factors, and results vary from person to person.

Having said that, you might see weight loss in your first month of treatment. Hers customers report an average weight loss of nine pounds in their first month taking compounded GLP-1 injections.*

Our guide dives more into how effective compounded semaglutide is.

FYI, compounded drug products aren’t approved or evaluated by the FDA for safety, efficacy, or quality.

*Based on self-reported data from approximately 2,100 Hers customers on a personalized treatment plan, including compounded GLP-1 injections, along with a reduced-calorie diet and exercise. Customers reported their weight at their initial medical consultation and their first check-in approximately four weeks later. Stopping weight loss treatment has been shown to result in weight regain.

Semaglutide is also a diabetes drug that can help regulate blood glucose levels. It can take a few weeks or months to notice any changes on that front as well.

For example, a 2024 study — also funded by Novo Nordisk — looked at more than 2,100 participants with type 2 diabetes. They took a weekly 1-milligram dose of Ozempic for 90 days. The average reduction in HbA1c (hemoglobin HC1 test), which measures average blood sugar levels, was 1.2 percent.

So, you may see improvements within your first few months of semaglutide treatment. But again, it can depend on the type and dose of semaglutide you’re taking, and it varies from person to person.

Semaglutide continues to work long-term for blood sugar control and diabetes management.

How long before semaglutide starts working? Quite a few factors can affect this.

Here’s a breakdown:

• Your biology and health profile. Everyone reacts differently to medication and has different factors affecting how quickly or easily they can lose weight. That can include medical conditions, other medications, and genetics.

• Your dose. To minimize semaglutide side effects, your prescribing healthcare provider will probably start you on a low dose that gradually increases over the course of several weeks or months. You may find the lowest dose doesn’t do much for you, but semaglutide begins working as your dose increases.

• The form of semaglutide you’re using. Semaglutide injections may be more effective than pills for some patients.

• If you forget to take a dose. Don’t worry — it’s not the end of the world if you forget to take a dose of semaglutide for weight loss. But it could delay how soon the medication works for you because it can take some time for the drug to build up in your system.

• Your lifestyle. Semaglutide works best when you make lifestyle changes, like eating more whole foods and doing more physical activity. The changes you make and other lifestyle factors can affect how effective semaglutide is. For instance, your sleep, stress levels, exercise habits, and how much of a calorie deficit you’re in can impact your weight loss journey.

• What changes you’re looking for. At the risk of being overexplanatory, how fast semaglutide works kind of depends on your definition of “works.“ The drug starts working as soon as you take it, but it can be days or weeks before you feel the effects (like appetite suppression). Initial weight loss or blood sugar changes might happen after a few weeks or months, and significant changes in your weight and health could take months or even upwards of a year.

Even more factors can affect how quickly you lose weight. Check out our weight loss timeline to explore them all.

You can also learn about the common side effects of semaglutide (and less common ones) in our blog.

If you Googled “how long for semaglutide to work,” we’ve got you. Here’s the TL;DR on how long it takes semaglutide to work:

• The key point to remember is that semaglutide starts working right away, but it can take a few weeks or months to get the full effect. That goes for appetite changes, weight loss, and diabetes management.

• For weight loss, you might start to feel some of the effects of semaglutide (like a reduced appetite or fewer cravings) early on and then notice some weight loss in your first month of treatment. It may also take a few months before you see significant weight loss.

• Either way, try not to obsess over how quickly you see results. Focus instead on all the great steps you’re taking toward better health. (Go you!)

• If you feel like semaglutide isn’t working for you, though, reach out to your prescribing healthcare provider. They may recommend a higher dose, a few lifestyle tweaks, a different medication, or just giving it more time.

Comparing your options? We’ve covered how long it takes metformin to work, a diabetes drug prescribed off-label for weight loss.

And if you want to get started with weight loss medications, you can take our weight loss assessment to see if you’re a good candidate.