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The cheap version advertised all over the internet is not a generic. There is no generic. And the legal basis that allowed most of that market to exist ended in 2025 — which means a lot of what is still being sold is being sold in defiance of it.
Semaglutide and tirzepatide came off the FDA shortage list in February and December 2024–25, and the deadlines for pharmacies to stop compounding copies passed in April and May 2025. The FDA has logged 990 adverse event reports for compounded semaglutide and over 730 for compounded tirzepatide as of 31 May 2026 — and says these are underreported. Many products used salt forms the FDA says have no lawful basis for compounding, and the most common harm reported is straightforward overdose from measuring the wrong amount.
Why compounded versions existed at all
US law allows compounding pharmacies to make copies of an approved drug when that drug is on the FDA’s shortage list. Semaglutide and tirzepatide were both in shortage through 2023 and 2024, and a large industry grew up in that window — telehealth sites, med spas, and online sellers offering the same molecules at a fraction of brand pricing.
That was legal, conditionally, because of the shortage. It was never a generic. A generic requires patent expiry and an approval process demonstrating equivalence; neither has happened for these drugs.
What changed in 2025
The shortages resolved, and with them the legal basis.
| Tirzepatide | Semaglutide | |
|---|---|---|
| Removed from shortage list | 19 December 2024 | 21 February 2025 |
| Deadline for 503A pharmacies | 18 February 2025 | 22 April 2025 |
| Deadline for 503B outsourcing facilities | 19 March 2025 | 22 May 2025 |
After those dates, compounding a product that is “essentially a copy” of the commercially available drug is restricted. There is a narrow carve-out — the FDA has said it does not intend to act against a compounder filling four or fewer prescriptions of such a product per month, and a prescriber can document a clinically significant difference for an individual patient — but that is a narrow exception, not a business model.
The practical test for a buyer is simple. An operation shipping compounded semaglutide at volume, to anyone who fills in a form, is not operating inside that exception.
The salt form problem
A large share of the compounded market used semaglutide sodium or semaglutide acetate rather than the semaglutide base in the approved products.
The FDA’s position is direct: it does not have information on whether these salts have the same chemical and pharmacological properties as the active ingredient in the approved drug, and they are not a lawful basis for compounding.
Read plainly, that means nobody has established that the substance in the vial behaves the same way in the body as the drug in the trials. Every efficacy figure you have read — the 20.2%, the 20% cardiac risk reduction — was generated with the approved molecule. Those numbers do not automatically transfer to a different salt of it made by a third party.
Dosing errors, which are the main harm
This is the most common and most avoidable problem, and it is a design failure rather than a chemistry one.
The approved products come in pre-filled pens with fixed doses. Compounded versions typically arrive as a vial and a syringe, and the patient measures the dose themselves.
The FDA reports errors from two directions: patients measuring and self-administering incorrect doses, and health care professionals miscalculating doses. Some patients received amounts exceeding the approved labelling — higher single doses, more frequent dosing, or accelerated titration schedules that skip the slow escalation the approved products are designed around.
The classic version of this error is confusing units with millilitres on an insulin syringe, which can produce a dose several times what was intended. With a drug whose main side effects are severe nausea and vomiting, a large accidental overdose is not a minor event.
The slow dose escalation in the approved products is not caution for its own sake. It is what keeps the gastrointestinal side effects tolerable — and even then, 5.6% of trial participants stopped semaglutide because of them.
What the FDA has actually recorded
As of 31 May 2026, the FDA had received 990 adverse event reports involving compounded semaglutide and more than 730 involving compounded tirzepatide.
The agency adds an important qualification: adverse events from compounded versions are underreported, because state-licensed pharmacies face limited federal reporting requirements. The real figures are higher by an unknown margin.
The FDA also warns about products sold outside the licensed system entirely — “research chemical” semaglutide, peptide vendors, and overseas sellers — which may be counterfeit, contain the wrong ingredient, or contain the wrong amount. Nothing about those products has been verified by anyone.
If you are buying anyway
Cost is a real reason people end up here, and saying “just use the brand” ignores that these drugs are expensive and coverage for weight indications is patchy. So, practically:
Use a state-licensed pharmacy, and check the licence. Boards of pharmacy publish verification tools. This is the single highest-value check available to you.
Ask what form of the drug it is. If the answer is semaglutide sodium or semaglutide acetate, that is the salt form the FDA has flagged.
Never buy from a source that does not require a prescription. A seller happy to skip that is skipping everything else too — including the thyroid and pancreatitis contraindications that make these drugs unsuitable for some people.
Do not self-adjust the dose. Faster titration produces more side effects, not faster results.
Compare against the real price first. Manufacturer direct-purchase programmes and pharmacy discount pricing have moved substantially since the shortage ended, and the gap that made compounded versions compelling is not what it was in 2023.
And if you are still deciding whether any of this is worth it, the actual trial evidence is here — along with the finding that most of the weight returns when you stop.
Sources
- US Food and Drug Administration. FDA’s concerns with unapproved GLP-1 drugs used for weight loss. FDA
- US Food and Drug Administration. FDA clarifies policies for compounders as national GLP-1 supply begins to stabilize. FDA
- Aronne LJ, Horn DB, le Roux CW, et al. Tirzepatide as compared with semaglutide for the treatment of obesity (SURMOUNT-5). American College of Cardiology
This article is for information only and is not medical advice. It cannot account for your individual circumstances. Talk to a doctor about your own situation, particularly before starting or stopping any prescription medication.