Compounded GLP-1s: what the law says and what the evidence shows

If you have been offered semaglutide or tirzepatide at a price far below the brand, you were probably offered a compounded version. Compounded medicines are made by a pharmacy rather than by the company that developed the drug and got it approved.

Three things are worth knowing before you decide anything.

• A compounded drug is not an FDA approved drug. The FDA does not review it for safety, effectiveness or quality before it is sold.
• The legal ground shifted in 2025. Large scale compounding of these two molecules was allowed because the approved products were in shortage. Those shortages were declared over, and that permission ended.
• The evidence on compounded versions is thin. There is one head to head comparison worth knowing about, and it did not favour the compounded product.

None of that means every compounded prescription is dangerous or that everyone taking one was harmed. It means you should know what you are buying.

Compounding is when a licensed pharmacist prepares a medicine for a patient rather than dispensing a manufactured product. It has a long and legitimate history, for example making a liquid version for someone who cannot swallow a tablet, or leaving out an ingredient someone is allergic to.

Federal law recognises two kinds of compounder:

Section 503A. A state licensed pharmacy or physician, compounding for an individual patient with a prescription. Small scale and patient specific.

Section 503B. A registered outsourcing facility, which may compound in batches without a prescription for a named patient, and which has to follow federal manufacturing quality rules.

Both categories come from the Drug Quality and Security Act of 2013, and both sit in federal law at 21 U.S.C. sections 353a and 353b.

Neither category is allowed to make something that is "essentially a copy" of a commercially available FDA approved drug. That is the point. Compounding exists to fill a genuine individual need, not to produce a cheaper version of a drug that already exists.

There is one major exception. While an approved drug is on the FDA's official shortage list, that restriction is relaxed, because the alternative is patients going without.

That exception is the entire reason a compounded GLP-1 industry appeared. When the shortage ended, the legal basis ended with it.

These are the FDA's own dates.

Tirzepatide (the molecule in Mounjaro and Zepbound). FDA determined the shortage was resolved on 19 December 2024. Enforcement discretion ended 18 February 2025 for 503A pharmacies and 19 March 2025 for 503B outsourcing facilities.

Semaglutide (the molecule in Ozempic and Wegovy). FDA determined the shortage was resolved on 21 February 2025. Enforcement discretion ended 22 April 2025 for 503A pharmacies and 22 May 2025 for 503B outsourcing facilities.

On 1 May 2026 the FDA proposed going further, by removing semaglutide, tirzepatide and liraglutide from the list of bulk substances that outsourcing facilities may compound from, on the basis that there is no clinical need. The comment period closed on 29 June 2026.

Because of a narrower argument. The law says a compounded product is not "essentially a copy" if a change is made for an identified individual patient and that change produces a significant difference for that patient, as judged by the prescriber. This is why you will see compounded products described as "personalised," or combined with something like vitamin B12, or offered at doses that do not match the approved product.

Whether that argument holds when a product is mass marketed to thousands of people is exactly what the FDA has been pressing on. In February and June 2026 the FDA issued warning letters to telehealth companies over how these products were being advertised.

What this means for you, practically: the legal footing of a compounded GLP-1 offer is not something to assume. It is something to ask about.

The FDA has published the specific claims that telehealth companies must not make about compounded drugs. You can run this list against any website in about a minute. If you see one of these, that is a real signal.

1. Branding that implies the telehealth company made the drug. If their name is on the vial, ask who actually compounded it.
2. Calling it a generic version of, or the same as, an FDA approved drug. There is no generic Ozempic or Wegovy. A compounded product is not a generic.
3. Saying or implying it is FDA approved, or has been evaluated for safety and effectiveness. It has not been.
4. Saying it is clinically proven to produce the same result as the approved drug. No compounded GLP-1 has been through that kind of trial.
5. Describing the source as an "FDA approved" or "FDA licensed" pharmacy or outsourcing facility. In the FDA's own words, compounding facilities "are not 'FDA-approved' or 'FDA-licensed' entities."

A very common version of the second claim is the phrase "same active ingredient as" followed by a brand name. The FDA has quoted that exact language back to companies in warning letters.

These are the agency's stated concerns, not ours.

Dosing errors. The FDA has received multiple adverse event reports, some involving hospitalisation, connected to dosing errors with compounded injectable semaglutide. Some involved patients measuring the wrong dose themselves. Some involved being prescribed doses beyond the approved label, through larger single doses, more frequent dosing, or faster increases.

Different active ingredients. Some products sold as semaglutide have used salt forms, semaglutide sodium or semaglutide acetate, which the FDA says are different active ingredients from the ones in the approved drugs.

Ingredient quality. The FDA has an import alert in place to stop GLP-1 raw ingredients with potential quality problems entering the country.

Storage and shipping. The agency has received complaints of product arriving warm, or with insufficient ice packs to hold it at the right temperature.

Fake and counterfeit product, including product with false information printed on the label.

Reported adverse events. As of 31 May 2026, the FDA had received 990 reports relating to compounded semaglutide and more than 730 relating to compounded tirzepatide.

Two molecules cannot be compounded at all. Retatrutide and cagrilintide have never been FDA approved, so there is no lawful route to compound them. If you are offered either, something is wrong.

This is the honest answer, and it is shorter than anyone would like.

There has never been a randomised trial comparing a compounded GLP-1 to an approved one.

There is one useful real world comparison. A digital weight loss service compared 923 patients on compounded semaglutide with 1,858 on the FDA approved product, using the same dose escalation schedule, over four months.

• Average weight loss was 9.11 percent on compounded versus 9.87 percent on approved.
• Reaching at least 10 percent loss: 44.6 percent versus 50.5 percent.
• Reaching at least 15 percent loss: 12.8 percent versus 21.4 percent.

So the compounded group did lose weight, and did meaningfully worse at the higher thresholds.

Side effects in that study were slightly lower in the compounded group, 71.6 percent against 77.4 percent. That difference was driven entirely by mild side effects. There was no difference in moderate or severe ones.

A 2026 review in the Annals of Pharmacotherapy concluded that compounded semaglutide and tirzepatide products use unique formulations whose efficacy and safety are largely unknown.

One number you will see quoted, with the caveat that usually gets left off. An analysis of the FDA's adverse event reporting database found much higher reporting odds for compounded products on quality problems, including preparation errors and contamination. That database is a voluntary reporting system. It can show that a signal exists. It cannot tell you how often something happens, and it cannot prove cause. Anyone quoting those figures as a rate is overstating them, and we are not going to do that.

• Is this medication FDA approved, or is it compounded?
• Which pharmacy or outsourcing facility actually makes it, and are they registered?
• Is the active ingredient semaglutide or tirzepatide, or a salt form?
• What is the total cost including refills, and what happens if I stop?
• Who is the prescriber, and are they licensed in my state?
• How is it shipped, and what should I do if it arrives warm?

We are not telling you that compounded medication is unsafe, or that you should stop taking something a clinician prescribed you. That is a conversation for you and a licensed clinician who knows your history.

We are telling you that a compounded GLP-1 is a different product from the approved one, that the rules changed in 2025, that the comparative evidence is thin and does not favour it, and that the FDA has published a specific list of claims that should make you look harder.

If you are choosing on price, it is also worth knowing that the approved products got much cheaper in 2026. There are now several routes, including federal ones, that did not exist a year ago. We cover those separately.