How does Wegovy work?

Reviewed by Yael Cooperman, MD, Ro, 

Written by Amelia Willson 

Reviewed by Yael Cooperman, MD, Ro, 

Written by Amelia Willson 

last updated: Mar 04, 2024

5 min read

If you struggle to manage your weight with diet and exercise alone, you may be interested in prescription medication options that help with long-term weight loss. Wegovy, a prescription drug that helps with chronic weight management when combined with exercise and a low-calorie diet, is one option to consider. Continue reading to learn more about how Wegovy works for weight loss, potential side effects, cost, and more.

Wegovy Important Safety Information: Read more about serious warnings and safety info.

Weight loss

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How does Wegovy for weight loss work?

Wegovy works for weight loss in a few ways, but the common denominator is that Wegovy makes you feel full. In theory, when you feel full, you will eat less and lose weight. Here’s how Wegovy works for weight loss.

Wegovy impacts your hunger hormones

The active ingredient in Wegovy is called semaglutide. Semaglutide works by mimicking GLP-1, a hormone that regulates appetite and satiety, or fullness. GLP-1 receptor agonists like Wegovy activate the receptor that the naturally occurring hormone binds to, which triggers a cascade of responses in the brain and throughout the body typically triggered after you eat. The medication plays a role in how your body processes energy, eventually reducing appetite and promoting weight loss

Who is eligible for Wegovy?

Wegovy is recommended for people with obesity (defined as having a BMI of 30 or higher) or those who have overweight (with a BMI of 27 or higher) along with a weight-related health condition, such as type 2 diabetes, high blood pressure, or high cholesterol

Some healthcare providers may prescribe Wegovy off-label for weight loss, even if you do not match these criteria precisely. They can use their clinical judgment to determine if Wegovy is the right treatment for you.  

How to administer Wegovy

The prescription pen comes pre-filled with a single dose of Wegovy, which you inject subcutaneously (under the skin) in your abdomen, upper arm, or thigh using the attached needle on the pen. Wegovy injections should be done once a week, around the same time of day, either with or without meals. It comes in five doses: 0.25 mg, 0.5 mg, 1 mg, 1.7 mg, and 2.4 mg. When not in use, you should store Wegovy medication in your refrigerator.

How long does it take to lose weight on Wegovy?

The effects of Wegovy start almost immediately after you start using the medication, but it can take about a month to notice results. In one study, people on Wegovy who adhered to lifestyle changes like diet and exercise lost about twice as much weight within the first month of treatment compared to people on a placebo. That amounted to over 2% of their body weight in the first month of treatment compared to less than 1% in the control group. 

As the trial went on, the gap between the subjects receiving a placebo and those receiving Wegovy continued to grow. After 68 weeks (about a year and four months), the participants taking semaglutide (the active ingredient in Wegovy) lost nearly 15% of their body weight on average, compared to less than 3% in the placebo group. 

In addition to losing a significant amount of weight, those taking semaglutide also experienced other improvements in their cardiometabolic health and reported better physical function.

Although all GLP-1 medications (typically prescribed to treat diabetes) can lead to weight loss, research suggests Wegovy may be more effective than other drugs at reducing body weight in people with a combination of type 2 diabetes and overweight or obesity. 

Does Wegovy have any side effects?

Wegovy’s side effects are typically gastrointestinal and range from mild to moderate. Nausea, diarrhea, vomiting, and constipation are the most common side effects, usually lessening over time as you continue using the drug (Singh, 2022; Wilding, 2021). Additional side effects of Wegovy may include (FDA, 2021):

Severe side effects of Wegovy

Severe side effects of Wegovy may include allergic reactions, gallbladder disorders, pancreatitis (inflammation of the pancreas), kidney failure, increased heart rate, and, in people with type 2 diabetes, hypoglycemia (low blood sugar) or diabetic retinopathy (vision loss or changes).

The US Food and Drug Administration (FDA) has issued a black box warning for Wegovy. Animal studies have found that semaglutide increases the risk of thyroid tumors in rodents. While it is not known if it has the same effect in humans, Wegovy should not be used by people with multiple endocrine neoplasia syndrome type 2 or with a personal or family history of thyroid cancer.

Wegovy warnings

Wegovy is not for everybody. Experts still don’t know whether it is safe to use other weight loss products or supplements while taking Wegovy, so your healthcare provider may recommend against using those. Also, Wegovy should not be used with other glucagon-like peptide-1 (GLP-1) receptor agonists, such as Ozempic or Rybelsus. Finally, Wegovy is not recommended for people who:

  • Have a history of pancreatitis

  • Are pregnant

  • Have a personal or family history of medullary thyroid carcinoma

Before using Wegovy, tell your healthcare provider about your personal and family medical history and any medications you are currently taking.

Ozempic Important Safety Information: Read more about serious warnings and safety info.

Wegovy vs. Ozempic

If you follow weight loss news, you’ve probably heard of Ozempic, touted by many celebrities for its successful weight loss management. If you’re in the market for a weight loss medication yourself, you may wonder, are Wegovy and Ozempic the same thing? Yes and no. Wegovy and Ozempic contain the same active ingredient but are available in different dosages and sold under different brand names. 

The FDA has approved Wegovy for chronic weight management in people 18 years and older with either:

In contrast, the FDA has approved Ozempic for:

  • Controlling blood sugar in adults over 18 years old with type 2 diabetes mellitus

  • Reducing the risk of major cardiovascular health problems, such as heart attack, stroke, and death in adults with type 2 diabetes and heart disease

The way you use the Wegovy and Ozempic pens is another difference between the medications. Injectable Wegovy pens each have a built-in needle. After you use the pen once, you dispose of the pen in a sharps container. Ozempic, on the other hand, comes with needles that you attach to the injector pen before each use. You dispose of the needle in a sharps container but continue using the same pen for several more uses.

Another difference between Wegovy and Ozempic is the dosages that are available. The maximum dose of Ozempic is 2.0 mg, while the maximum dose of Wegovy is 2.4 mg. 

Since Ozempic is not FDA-approved for treating overweight or obesity, it may be easier to get insurance approval for Wegovy for some people. Likewise, if you have diabetes, it may be easier for you to get insurance coverage for Ozempic than for Wegovy. 

How much does Wegovy cost?

The cost of Wegovy will vary depending on many factors. These factors include whether or not you have health insurance, if your health insurance company covers Wegovy (not every health insurance company does), your dosage, and what pharmacy you use.

Wegovy is only available as a brand-name drug, not as a generic drug. Because brand-name drugs usually cost more than their generic counterparts, the cost of Wegovy can be quite high. If you’ve been prescribed Wegovy and have concerns about paying for your medication costs, talk with your doctor or pharmacist and visit the Wegovy manufacturer’s website to look for coupons, see if you’re eligible for a Wegovy savings card, and other support options.

If eating a healthy diet and exercising isn’t working to help you maintain a healthy weight, it might be time to explore prescription options. Make an appointment with your healthcare provider to find out if Wegovy is right for you.


If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.

How we reviewed this article

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.

Current version

March 04, 2024

Written by

Amelia Willson

Fact checked by

Yael Cooperman, MD

About the medical reviewer

Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.

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