What Is Semaglutide? How It Works, Uses, and What to Know

Quick Answer

What is semaglutide? Semaglutide is a GLP-1 receptor agonist, a prescription medication that lowers blood sugar and reduces appetite. The FDA approved semaglutide for type 2 diabetes in 2017 and for chronic weight management in 2021. It is sold under the brand names Ozempic, Wegovy, and Rybelsus, all made by Novo Nordisk.

Key Takeaways

• What is semaglutide? It is a GLP-1 receptor agonist that curbs appetite and steadies blood sugar.
• The FDA approved semaglutide for type 2 diabetes in 2017 and for weight management in 2021.
• Brand names include Ozempic, Wegovy, and Rybelsus, all from Novo Nordisk.
• In the NEJM STEP 1 trial, semaglutide produced about 14.9 percent mean weight loss over 68 weeks.
• Compounded semaglutide is not FDA-approved and is prepared per individual prescription by a licensed pharmacy.

What is semaglutide, in simple terms?

What is semaglutide at the most basic level? Semaglutide is a prescription medicine that mimics a natural gut hormone called GLP-1. That hormone tells your brain you are full and helps control blood sugar. Semaglutide copies it and makes the signal last much longer.

The drug comes from Novo Nordisk. According to the FDA, semaglutide first earned approval in 2017. Since then it has become one of the most widely used weight and diabetes medications in the United States.

What is semaglutide used for?

Semaglutide has two main approved uses. The FDA cleared it for type 2 diabetes in 2017 under the brand Ozempic, then for chronic weight management in 2021 under the brand Wegovy. In 2024, the FDA also approved semaglutide to lower the risk of major cardiovascular events in certain adults.

• Type 2 diabetes, to improve blood sugar control.
• Chronic weight management, for adults with obesity or overweight plus a related condition.
• Cardiovascular risk reduction, for adults with heart disease and excess weight.

How does semaglutide work in the body?

Here is where the question shifts from what is semaglutide to how does semaglutide work. The drug acts in several places at once. It targets the pancreas, the stomach, and the brain. Together these effects lower blood sugar and reduce hunger.

• It prompts the pancreas to release insulin when blood sugar is high.
• It lowers glucagon, a hormone that tells the liver to release stored sugar.
• It slows how fast the stomach empties, so meals feel filling for longer.
• It acts on appetite centers in the brain, so hunger and cravings drop.

The appetite effects are what drive weight loss. You eat less without fighting constant hunger. To protect muscle while you lose fat, aim for enough daily protein. The AHC GLP-1 protein calculator gives you a target.

What are the brand names for semaglutide?

Semaglutide is sold under three brand names, all from Novo Nordisk. They share the same active ingredient but differ in approved use, dose, and form. A fourth column shows compounded semaglutide, which is a different category.

What is the difference between semaglutide and Ozempic or Wegovy?

This trips a lot of people up. What is semaglutide versus Ozempic? Semaglutide is the drug. Ozempic and Wegovy are brand names for that same drug. So Ozempic is semaglutide approved for diabetes, and Wegovy is semaglutide approved for weight management at a higher dose. The molecule does not change. The label and the dose do.

How much weight can you lose on semaglutide?

Results vary by person. The clearest evidence comes from the NEJM STEP 1 trial, which enrolled 1,961 adults with obesity or overweight without diabetes. Over 68 weeks, the semaglutide group lost about 14.9 percent of body weight, compared with 2.4 percent on placebo, roughly 34 pounds on average.

These results came alongside diet and activity changes. To set a realistic pace for your own goal, map your timeline with the AHC weight loss planner.

How fast does semaglutide work?

A common follow-up to what is semaglutide is how fast it works. The dose starts low and rises slowly to limit side effects. A typical schedule begins around 0.25 mg once weekly for the first four weeks, then steps up over the following months under provider guidance.

Appetite often drops within the first few weeks. Visible weight change usually builds over two to three months and beyond, paired with diet and activity. Some people notice early results, while others take longer. The dose and the response are individual.

How long do you stay on semaglutide?

Another part of what is semaglutide is how long you take it. There is no single answer. Many people use semaglutide for six to twelve months, and others stay on it for one to two years or longer. Because obesity is a chronic condition, clinicians often view semaglutide as a long-term, even lifelong, therapy rather than a quick fix.

In practice, many people stop sooner. A 2025 analysis in JAMA Network Open found that most patients discontinue these drugs within two years, often due to cost, access, or side effects. A provider helps you decide how long treatment makes sense for you.

What happens when you stop semaglutide?

A big part of what is semaglutide in practice is what happens after you stop. Appetite tends to return once the medication clears, and some weight regain is common. In one widely cited trial, participants regained about two-thirds of the weight they had lost within a year of stopping once-weekly semaglutide. This is not a willpower failure. The body drifts back toward its prior set point.

Clinicians often suggest tapering with provider guidance rather than stopping cold turkey, plus protein-forward eating and resistance training to protect results. Sustainable habits matter most after the medication ends.

Does semaglutide cause muscle loss or Ozempic face?

Part of what is semaglutide as a real-world experience involves these two concerns. Rapid weight loss can include some muscle, not only fat. To protect muscle, aim for adequate protein, often around 1.2 to 1.5 grams per kilogram of body weight, and add resistance training two to three times a week.

Ozempic face is a nickname for facial volume loss after fast weight loss. It reflects fat loss in the face, not a unique drug toxicity, and is more common in people over 40 or those losing weight quickly. It does not affect health.

How long does semaglutide stay in your system?

Another question tied to what is semaglutide is how long it lingers. Semaglutide has a long half-life of about 160 hours, or roughly seven days, which is why it is dosed once weekly. After a final dose, it takes about five weeks for the drug to clear the body. There is no safe way to speed that up.

What are the side effects of semaglutide?

Most side effects involve the gut, because semaglutide slows digestion. In the STEP 1 trial, nausea affected about 44 percent of the semaglutide group and diarrhea about 31 percent. Most cases were mild to moderate and eased over time, and only about 5 percent stopped the drug because of them.

• Nausea, vomiting, diarrhea, or constipation, most common when starting or raising the dose.
• Stomach pain, bloating, or burping.
• Lower appetite and feeling full quickly.
• Gallbladder problems, including gallstones, which can occur with rapid weight loss.

Less common but more serious effects include pancreatitis, gallbladder disease, and rare reports of kidney or liver problems. Seek medical care for severe, lasting abdominal pain. The FDA label carries a boxed warning. In animal studies, semaglutide caused thyroid C-cell tumors, and whether it does so in humans is not known. People with a personal or family history of medullary thyroid carcinoma or MEN 2 should not use it.

Who should not take semaglutide?

Semaglutide is not right for everyone. A provider screens for these situations before prescribing any form, brand or compounded.

• A personal or family history of medullary thyroid carcinoma or MEN 2.
• A known allergy to semaglutide or any ingredient in the product.
• Pregnancy, plans to become pregnant, or breastfeeding.
• A history of pancreatitis or certain serious gastrointestinal conditions.

What is compounded semaglutide?

Compounded semaglutide is a version prepared by a licensed pharmacy from the active ingredient, based on a prescription written for one specific patient. It is not the same as the FDA-approved brands. The FDA notes that compounded drugs are not reviewed for safety, effectiveness, or quality before they reach patients.

With a brand like Ozempic, you get a standardized, FDA-reviewed product. With compounded semaglutide, you rely on the licensed provider who prescribes it and the licensed pharmacy that prepares it. Once you have a supply, the AHC guide on how to store compounded semaglutide helps keep it stable.

Is compounded semaglutide legal in 2026?

The rules changed recently and are still moving. Federal law let pharmacies compound copies of semaglutide while it sat on the FDA shortage list. When the shortage ended, that allowance closed. Here is the timeline.

1. February 21, 2025: the FDA removed semaglutide injection from its drug shortage list, ending the shortage-based compounding allowance.
2. Spring 2025: the enforcement grace periods for 503A pharmacies and 503B outsourcing facilities ended.
3. April 30, 2026: the FDA proposed removing semaglutide from the 503B bulk substances list, with a public comment window closing June 29, 2026.

One pathway stays open. Patient-specific compounding under section 503A continues under its own framework when a licensed provider documents a clinical need for a specific patient. A provider decides what is appropriate, case by case.

How much does semaglutide cost?

A practical part of what is semaglutide is the price. Brand-name semaglutide is expensive without insurance. List prices for Ozempic and Wegovy have run over 1,000 dollars per month. A 2025 KFF poll found that about half of adults who take GLP-1 drugs say they are difficult to afford, which is why many people look for lower-cost paths.

Alternate Health Club offers compounded semaglutide at a flat 129 dollars per month, with no membership fees and no dose-escalation markups. Compounded tirzepatide is 169 dollars per month. Access depends on provider approval after an individual evaluation.

How do you get semaglutide?

A final part of what is semaglutide is how to get it. Semaglutide is prescription-only in every form. You cannot buy it over the counter. The basic path looks like this.

• Check your starting point, including your BMI and health history.
• Complete an online evaluation that a licensed U.S. provider reviews.
• If appropriate, the provider writes a prescription and treatment ships to your door.

Curious whether your numbers fit a program? Start with the AHC BMI calculator, then take the evaluation to see what a licensed provider recommends.

Frequently Asked Questions

What is semaglutide?

What is semaglutide in one sentence? Semaglutide is a GLP-1 receptor agonist, a prescription medication that lowers blood sugar and reduces appetite. It is sold as Ozempic, Wegovy, and Rybelsus.

What is semaglutide used for?

Semaglutide is approved for type 2 diabetes and for chronic weight management, and to reduce cardiovascular risk in certain adults. A provider decides which use applies to you.

How does semaglutide work?

Semaglutide copies the GLP-1 hormone. It slows stomach emptying, curbs appetite in the brain, and helps the pancreas manage blood sugar. Those effects support weight loss and glucose control.

Is semaglutide the same as Ozempic?

Semaglutide is the active ingredient. Ozempic is a brand name for semaglutide approved for type 2 diabetes. Wegovy is semaglutide approved for weight management.

How much weight can you lose on semaglutide?

Results vary. In the NEJM STEP 1 trial, adults lost about 14.9 percent of body weight over 68 weeks, roughly 34 pounds, alongside diet and activity changes.

What are the main side effects of semaglutide?

Gastrointestinal effects lead the list: nausea, diarrhea, constipation, and stomach discomfort. Most are mild to moderate and ease over time. The FDA label carries a boxed warning about thyroid tumors seen in animals.

Is semaglutide safe?

FDA-approved semaglutide has a known safety profile with risks listed on its label. Compounded semaglutide is not FDA-approved. Discuss your history with a licensed provider before starting.

What is compounded semaglutide?

It is semaglutide prepared by a licensed pharmacy from an individual prescription. Compounded semaglutide is not FDA-approved and is not reviewed by the FDA for safety, effectiveness, or quality.

Is semaglutide available as a pill?

Yes. The oral tablet form of semaglutide is sold as Rybelsus for type 2 diabetes. Ozempic and Wegovy are weekly injections.

Do you need a prescription for semaglutide?

Yes. Semaglutide is prescription-only in every form. A licensed provider must evaluate you before prescribing it.

How long does it take semaglutide to work?

Appetite changes can show up within the first weeks, but the dose is raised slowly. Meaningful weight changes usually build over several months alongside lifestyle changes.

Is compounded semaglutide legal in 2026?

Mass-scale compounding of copies ended after the shortage resolved in February 2025. Patient-specific compounding under section 503A continues when a licensed provider documents a clinical need.

What is the difference between semaglutide and tirzepatide?

Semaglutide acts on one hormone pathway, GLP-1. Tirzepatide acts on two, GLP-1 and GIP, and has shown larger weight loss in trials. A provider helps you choose.

Can semaglutide be used just for weight loss?

The semaglutide product approved for weight loss is Wegovy. Some providers prescribe Ozempic off-label. A licensed clinician decides what is appropriate.

What is semaglutide made of?

What is semaglutide made of? The active part is the semaglutide molecule, a GLP-1 receptor agonist, combined with inactive ingredients for injection, or formed into a tablet in Rybelsus.

What is semaglutide approved to treat?

What is semaglutide approved to treat? The FDA approved semaglutide for type 2 diabetes and chronic weight management, plus cardiovascular risk reduction in certain adults.

What is semaglutide’s success rate for weight loss?

In the STEP 1 trial, 86.4 percent of people on semaglutide lost at least 5 percent of body weight, and about half lost 15 percent or more, alongside lifestyle changes.

What is semaglutide microdosing?

What is semaglutide microdosing? It means using smaller amounts than standard dosing, sometimes to ease side effects or maintain weight. Only do it under provider guidance.

What is semaglutide’s effect on appetite?

What is semaglutide‘s effect on appetite? It reduces hunger and cravings by acting on appetite centers in the brain and slowing how fast the stomach empties.

How fast does semaglutide work?

Appetite changes can appear within the first weeks, but the dose rises slowly. Most people see meaningful weight change over two to three months, alongside diet and activity.

How long do you stay on semaglutide?

Many people use it for six to twelve months or longer. Because obesity is chronic, it is often a long-term therapy. A provider helps you decide what is right.

What happens when you stop semaglutide?

Appetite usually returns and some weight regain is common, with studies showing many people regain about two-thirds of lost weight within a year. Tapering with a provider and strength training can help.

How long does semaglutide stay in your system?

Semaglutide has a half-life of about seven days and takes roughly five weeks to clear after the last dose.

What is Ozempic face?

Ozempic face is facial volume loss from rapid weight loss, not a drug toxicity. It is more common over 40 and with fast weight loss, and it does not affect health.

Does semaglutide cause muscle loss?

Rapid weight loss can include some muscle. Adequate protein and resistance training help protect muscle while you lose fat.

How do I find out if I qualify for semaglutide?

Take the AHC free online evaluation. A licensed U.S. provider reviews your answers and decides what is appropriate before any treatment ships.

Start with Alternate Health Club

Alternate Health Club is a LegitScript-certified telehealth platform. Want to know if a compounded GLP-1 program fits your situation? Take the free online evaluation. Independently licensed U.S. providers review every assessment, and approved treatment ships to all 50 states at flat monthly pricing, with no membership fees and no dose-escalation markups.

Medical disclaimer

This article is for educational purposes only and is not medical advice. It does not create a doctor-patient relationship. Compounded medications referenced here are not FDA-approved and have not been reviewed by the FDA for safety, effectiveness, or quality. Prescriptions are issued only by independently licensed U.S. clinicians after an individual evaluation, and providers retain full discretion to prescribe or decline treatment. Results vary by individual. Brand names belong to their respective trademark owners and are used only for educational context. Always talk with a licensed healthcare professional before starting, stopping, or changing any medication.