What is semaglutide or tirzepatide, and are compounded versions the same thing?

What is semaglutide?

Semaglutide is a lab-made version of GLP-1, a hormone your gut releases after you eat. GLP-1 tells the brain you are full, slows the stomach so food leaves it more gradually, and helps the pancreas release insulin when blood sugar is high. It is made by Novo Nordisk.

The same molecule is sold under different brand names. Wegovy is approved for weight management and is taken once a week by injection or once a day as a pill. Ozempic and Rybelsus are approved for type 2 diabetes. The semaglutide page has the details and the trials.

What is tirzepatide?

Tirzepatide is a lab-made molecule that switches on two gut-hormone receptors, one for GLP-1 and one for GIP. Both hormones are released after meals and help control blood sugar and appetite. It is made by Eli Lilly.

Zepbound is the brand approved for weight management and for moderate to severe obstructive sleep apnea in adults with obesity. Mounjaro is the brand approved for type 2 diabetes. Both are weekly injections. The tirzepatide page has the details.

How are semaglutide and tirzepatide different?

The head-to-head result is from SURMOUNT-5, an open-label trial of 751 adults with obesity and without type 2 diabetes, funded by Eli Lilly. People took the highest dose they could tolerate. One person's result can be higher or lower.

Are compounded semaglutide and tirzepatide the same thing?

No. A compounded drug is made by a pharmacy for an individual patient. It is not FDA-approved, and the FDA does not review it for safety, effectiveness or quality before it is sold. The name on the label is the same as the brand-name drug's ingredient, and that is where the match ends.

The FDA has said some compounders sell semaglutide salt forms, such as semaglutide sodium and semaglutide acetate. It says these are different active ingredients from those in approved drugs and that it knows of no lawful basis for using them in compounding.

Why were compounded versions ever so common?

Both medicines were in national shortage for a time, and federal law lets pharmacies compound copies of drugs on the shortage list. The shortages have ended and the rules are narrower now. The compounded versus brand-name page explains what changed, and the policy tracker follows the rules as they move.

Can I trust a product online labeled semaglutide or tirzepatide?

Be careful. The FDA has issued warning letters over illegally marketed semaglutide and tirzepatide sold online. It says these products may be counterfeit or contain the wrong or harmful ingredients, and it has warned about products falsely labeled "for research purposes" or "not for human consumption" that are sold for human use. The FDA says to get a prescription from your doctor and fill it at a state-licensed pharmacy. Retatrutide, a medicine still in trials, cannot be used in compounding under federal law. Read what to watch for in injection instructions before using anything you were given.

Are there pills?

Yes, two. Semaglutide is sold as the Wegovy pill, a once-daily tablet approved for weight management. A different medicine, orforglipron, is sold as Foundayo. The weight-loss pills guide explains how they differ from the injections.

What should I ask before starting either one?

The first visit page covers what a good appointment includes, and the week-by-week side effects page covers what to expect. Both medicines carry a boxed warning about thyroid C-cell tumors seen in rodents and are not for people with a personal or family history of medullary thyroid carcinoma or MEN 2.

Quick answers

What is semaglutide?

A lab-made copy of the gut hormone GLP-1, made by Novo Nordisk. It is sold as Wegovy for weight management and as Ozempic and Rybelsus for type 2 diabetes.

What is tirzepatide?

A lab-made molecule that activates both the GIP and GLP-1 receptors, made by Eli Lilly. It is sold as Zepbound for weight management and as Mounjaro for type 2 diabetes.

Is semaglutide the same as Ozempic?

Semaglutide is the active ingredient in Ozempic, Wegovy and Rybelsus. The brands differ in the conditions they are approved for and in how they are taken.

Is tirzepatide better than semaglutide?

In SURMOUNT-5, an open-label trial funded by Eli Lilly, adults with obesity lost an average of 20.2% on tirzepatide and 13.7% on semaglutide over 72 weeks. The best medicine for a person depends on their health, cost and coverage, which a clinician can weigh.

Are compounded semaglutide and tirzepatide the same as Wegovy and Zepbound?

No. Compounded drugs are made by pharmacies, are not FDA-approved and are not reviewed by the FDA for safety, effectiveness or quality.

Is compounded semaglutide safe?

The FDA has said compounded versions are not reviewed before sale and has received reports of serious adverse events, some linked to dosing errors. Ask a clinician about your own situation.

Questions to ask

• Which medicine and brand fit my health history and my coverage?
• If I am offered a compounded product, who makes it, and how does it differ from the brand-name drug?
• Which ingredient is in the product, and is it the same as the approved drug's?
• What side effects should I expect while the dose is raised, and when should I call?

What is still unknown

• Long-term safety beyond the trial lengths is still being learned for both medicines.
• The quality of any individual compounded product is not known, because compounded drugs are not reviewed before sale.
• The FDA's compounding questions-and-answers page was read (content current as of September 16, 2025). It explains the 503A and 503B terms and says compounded drugs are not FDA-approved, but it does not cover dosing or adverse event reports, so those points rely on the FDA's unapproved GLP-1 page.