How long does it take semaglutide to work?

Semaglutide is the active ingredient in the brand name medications Ozempic, Wegovy, and Rybelsus. Whether you’re taking semaglutide to lower your blood sugar or lose weight (or both), you’re probably wondering when you’ll start to notice the drug’s effects. 

So, how long does it take for semaglutide to work? The answer depends on a few factors, from your lifestyle to the dosage you’re taking. Below, we break down the research on when semaglutide starts working so you can get an idea of what to expect.

Semaglutide is the active ingredient in popular diabetes and weight loss drugs, such as Rybelsus and Ozempic (approved for type 2 diabetes) and Wegovy (approved for weight loss). Ozempic and Wegovy are additionally approved to lower the risk of experiencing a major cardiovascular event in people with both heart disease and type 2 diabetes (Ozempic) or heart disease and obesity or overweight (Wegovy). Rybelsus is an oral GLP-1 medication, while Ozempic and Wegovy are injectable medications.

Semaglutide works by mimicking a gut hormone called glucagon-like peptide-1 (GLP-1). This hormone gets released after you eat and plays a role in controlling your blood sugar levels and appetite. Semaglutide, and other GLP-1 medications, amplify GLP-1 signaling. 

Specifically, semaglutide and other GLP-1s work by slowing down digestion. This helps keep your blood sugar levels in check while also helping you feel full sooner. Semaglutide also encourages the release of insulin after you eat while limiting the production of glucose (when levels are elevated)—again, helping to keep your blood sugar levels in check. Finally, semaglutide is thought to influence your brain’s food reward center, affecting not only your appetite but also your cravings for certain foods. When taking semaglutide, many people note that they have better control over their eating and find fatty, calorie-dense foods less desirable than before.

Once you inject semaglutide, it starts working on receptors in your body soon after the first dose. But that doesn’t mean that you’ll see results right away. If you’ve just started taking semaglutide, either to control blood sugar levels, to lose weight, or both, it might take a bit longer until you see your weight going down and your blood sugar control improving. 

Some people may notice weight loss after a few weeks of taking semaglutide, while for others, it can take longer. Semaglutide tends to lead to weight loss, even if you’re not taking it for that reason specifically. 

Usually, people start to see noticeable results within the first three months. For example, in a study of Ozempic, people taking 1 milligram (mg) of semaglutide lost an average of 11 pounds in three months. In a study of Wegovy, people taking 1.7 mg and 2.4 mg dosages of semaglutide lost an average of 14 pounds, or 6% of their body weight, in three months. By six months, they lost an average of 27 pounds, or almost 11% of their body weight. 

In clinical trials of oral Rybelsus, people lost around 5–8 pounds after 26 weeks, or about 2.5–4% of their baseline weight. People lost more weight on the higher dose. With injectable semaglutide, the weight loss is more pronounced and occurs earlier. In one study, at the 28-week mark, patients taking 1 mg of semaglutide lost approximately 7% of their weight, and those taking 2.4 mg of semaglutide lost about 9.6% of their weight. Results tend to be even better for those taking Wegovy because people are exposed to even higher doses of semaglutide.

While semaglutide starts working as soon as you take it, it might take some time before you notice the results in your blood sugar levels. 

In clinical trials, Ozempic lowered fasting blood sugar levels by 22% compared to placebo after 12 weeks of treatment. Postprandial glucose levels (measured two hours after eating) decreased by 36%. By week 30, only 28% of people on placebo had an HbA1c (the average blood sugar levels over the last three months) less than 7%, whereas as much as 70% or more of people on any dose of Ozempic achieved an A1C of less than 7%. 

In clinical trials of Rybelsus, HbA1c levels reduced by 1.2 to 1.4% from an average of 8% after 26 weeks of treatment. 

If you’re taking semaglutide to control type 2 diabetes, it can take several weeks to achieve the full effect, but it does work well for many people. According to the manufacturer of semaglutide, the concentration of the drug in the bloodstream typically reaches a steady level after 4–5 weeks of once-weekly use. If you are not noticing an immediate change in your sugar levels or A1C, be patient. Remember, changes can take time.

You’ll know semaglutide is working if you notice you’re feeling less hungry than you used to, getting full sooner during a meal, or having fewer cravings for foods. So, when does semaglutide start working on your appetite? While you may notice initial effects sooner, studies have observed a significant reduction in appetite within the first three months of taking semaglutide.

At the three-month mark, people taking 1 mg of semaglutide (a typical dose of Ozempic) reported less hunger, more control over their eating, and fewer food cravings, especially for high-fat foods. When compared to those taking a placebo, people taking semaglutide ate 24% less overall and approximately 35% less during their lunch and evening meals. This resulted in an average weight loss of 11 pounds, mostly from body fat.

If you’re taking semaglutide for weight loss, it is possible that you’ll have less of an appetite after a couple of weeks of continuous use of semaglutide, but significant weight loss may take a little bit longer. Weight loss is a complex process, and how fast you lose weight on semaglutide varies from person to person. Having said that, there are a few factors that can affect how fast semaglutide starts to work. 

Adherence to treatment

First up, one of the factors that affects how fast semaglutide works is your own approach to semaglutide treatment. Semaglutide injections like Ozempic and Wegovy should be taken once a week, on the same day each week, while oral Rybelsus should be taken once a day, with 4 ounces (or less) of plain water, at least 30 minutes before you consume anything else. These dosage guidelines are based on the drug’s half-life (or how long it takes before half of the drug has left your body). Whichever version of semaglutide you’re taking, it’s important to take it consistently and as directed in order to ensure it works as well as possible.

All forms of semaglutide—Ozempic, Wegovy, Rybelsus, and compounded semaglutide—are also intended to be taken with lifestyle changes like diet and exercise. These lifestyle changes may not only aid in weight loss but also help you establish healthy habits that will keep the weight off long-term. Studies show that people who get help to improve their diet and activity levels experience greater weight loss—and added health benefits related to weight loss—than those who don’t. 

Other lifestyle factors

While diet and exercise are recommended for anyone taking semaglutide, they’re not the only lifestyle changes that can affect how long it takes for semaglutide to work. For example, both stress and poor sleep are tied to weight gain. 

If you regularly get fewer than 7 hours of sleep per night, now might be the time to change that. Chronic sleep deprivation makes you more likely to snack more, especially on less-healthy foods high in fat and carbohydrates. Aim to get 7–9 hours of sleep per night when possible.

Stress can also make it tough to sleep well and lose weight. Stress disturbs your sleep, cranks up your appetite, and makes you less motivated to work out—all of which can disrupt your weight loss efforts. Breathing exercises can help ease your worries and relax you into sleep. Other solid stress management techniques include cognitive-behavioral therapy, meditation, and exercise. 

Cigarette smoking and drinking alcohol are also linked with weight gain. Consider stopping smoking and limiting how much you drink.

Underlying health conditions

If you have any health conditions, that can also affect how quickly semaglutide works for weight loss. People with type 2 diabetes, for example, tend to lose weight more slowly on semaglutide and other GLP-1 medications. In one study of semaglutide, people with type 2 diabetes lost about 4% of their body weight after three months of taking semaglutide. People without type 2 diabetes, on the other hand, lost about 6% of their body weight in the same time period.

In one clinical trial of semaglutide, researchers calculated that people with type 2 diabetes can expect to lose about one-third less body weight than people without type 2 diabetes.

Dosage

The dosage of semaglutide you are taking can also affect how much weight you lose and how quickly it happens. All forms of semaglutide follow a ramp-up dosing period, where you start with a lower dose and gradually work your way up over a period of several weeks to months. Regardless of whether you are taking Ozempic, Wegovy, or Rybelsus, it will take some time before you reach your maintenance dosage and experience the full effects of the medication.

Having said that, people taking the highest dosage strength (2.4 mg) of semaglutide associated with Wegovy tend to lose more weight than those taking the 1 mg Ozempic dose of semaglutide. And people taking any form of semaglutide injection lose more weight than those on oral Rybelsus. 

Semaglutide starts working as soon as you start taking it. But, how long it takes before you see results can depend on a number of factors, including your dosage, other health conditions you have, and the lifestyle changes you make. In general, though, people start to notice improvements in their blood sugar levels, appetite, and body weight within the first three months of taking semaglutide.

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Every article on Health Guide goes through rigorous fact-checking by our team of medical reviewers. Our reviewers are trained medical professionals who ensure each article contains the most up-to-date information, and that medical details have been correctly interpreted by the writer.

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Current version

November 07, 2024

Written by

Amelia Willson

Fact checked by

Beverly Tchang, MD and Raagini Yedidi, MD

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About the medical reviewers

Beverly Tchang, MD

Beverly Tchang, MD, is an Obesity Medicine Advisor for Ro. She is also an assistant professor of Clinical Medicine at Weill Cornell Medicine in New York and triple board-certified in Internal Medicine, Endocrinology, and Obesity Medicine.

Raagini Yedidi, MD

Raagini Yedidi, MD, is an internal medicine resident and medical reviewer for Ro.