Compounded tirzepatide and compounded semaglutide were lawful only for as long as FDA listed the approved products as being in shortage. FDA declared the tirzepatide shortage resolved on December 19, 2024 and the semaglutide shortage resolved on February 21, 2025, then allowed short grace periods that ended on February 18 and March 19, 2025 for tirzepatide and April 22 and May 22, 2025 for semaglutide. Those dates have not moved, thirty telehealth companies have received FDA letters over how they marketed compounded versions, and FDA has proposed excluding both molecules from the 503B bulks list. A research vial of either peptide is not a substitute for any of this and is not sold here as one.

Why compounding was allowed at all

Section 503A of the Federal Food, Drug, and Cosmetic Act covers pharmacies and physicians compounding for individual prescriptions; section 503B covers outsourcing facilities that register with FDA. Both chains, and why a research vial belongs to neither, are defined in 503A, 503B and research-use-only: three supply chains that do not mix. FDA's own question-and-answer page puts the key point plainly: "Compounded drugs are not FDA-approved. This means that FDA does not verify the safety, effectiveness or quality of compounded drugs before they are marketed."

Neither section normally permits a compounder to make what is "essentially a copy" of a commercially available approved drug. The exception that opened the door was the shortage list. When FDA determines that an approved drug is in shortage, 503A pharmacies and 503B outsourcing facilities may compound it, and for a period both semaglutide and tirzepatide were on that list. Everything that followed was the closing of that exception, in two steps for each molecule: a determination that the shortage was resolved, then the end of a short enforcement-discretion period in which FDA said it would not act against compounders while they wound down.

The dates, from FDA's page

All four discretion dates are from FDA's page "FDA clarifies policies for compounders as national GLP-1 supply begins to stabilize," content current as of April 1, 2026. FDA's most recent tirzepatide determination is the December 19, 2024 one; some secondary sources give February 19, 2025 for the 503A date, and FDA's page says February 18. The semaglutide dates were litigated. FDA's page records that "On April 24, 2025, the district court denied the plaintiffs' preliminary injunction motion in Outsourcing Facilities Association v. FDA, 4:25-cv-00174 (N.D. Tex.) regarding compounded semaglutide," and the discretion periods ended as scheduled.

What the March 3, 2026 letters were

A year after the windows closed, FDA turned to the companies still advertising compounded versions. On March 3, 2026 the agency "announced the issuance of 30 warning letters to telehealth companies for making false or misleading claims regarding compounded GLP-1 products offered on their websites." The release describes the violations as "making claims implying sameness with FDA-approved products and obscuring product sourcing by advertising drug products branded with the telehealth firm's name or trademark without qualification, implying they are the compounder." The Commissioner's line in the release states the principle:

compounders should not try to compound drugs in a way that circumvents FDA's approval process.FDA Commissioner Marty Makary, FDA press release, March 3, 2026

Those thirty letters went to telehealth marketers of compounded drugs. They are a different set from FDA's letters to research-peptide sellers, which are addressed to a different problem, the sale of a "research use only" vial with claims that make it a drug. The two enforcement lines are often reported as one; they are not. The research-seller letters are the subject of what FDA reads on a website before it calls a research product a drug.

What is still open as of September 21, 2026

Two threads have not closed. First, FDA's April 1, 2026 page still describes a narrow residual policy:

FDA has stated, at this time, it does not intend to take action against a compounder for compounding a drug product that is essentially a copy of a commercially available drug product regularly or in inordinate amounts if the compounder fills four or fewer prescriptions of that compounded drug product during a calendar month.FDA, "FDA clarifies policies for compounders as national GLP-1 supply begins to stabilize," content current as of April 1, 2026

That is a statement about very small volumes and about enforcement priorities, not a reopening of the shortage window.

Second, on April 30, 2026 FDA announced that "it is proposing to exclude semaglutide, tirzepatide, and liraglutide on the 503B bulks list," stating that "after evaluating the nominations for these three substances, the FDA did not identify a clinical need for outsourcing facilities to compound semaglutide, tirzepatide, and liraglutide from bulk drug substances." The comment period closed June 29, 2026. As of September 21, 2026 we have not found a final decision on fda.gov or in the Federal Register. The same release explains what the list does: outsourcing facilities generally cannot compound from a bulk substance unless it appears on the 503B bulks list or the compounded drug is on FDA's shortage list at the time.

What a research vial is, and is not

Semaglutide and tirzepatide are on our GLP-1 and metabolic shelf as lyophilized research vials: semaglutide, a peptide of formula C187H291N45O59 and molecular weight 4114, and tirzepatide, formula C225H348N48O68 and molecular weight 4813, both per PubChem. That is the extent of the identity we claim for them.

A research vial is not a compounded drug. It is not made in a pharmacy or an outsourcing facility, it is not dispensed against a prescription, it is not formulated, and it is not covered by section 503A or 503B, which regulate compounders and say nothing about laboratory chemicals. It is not the approved product either. Ozempic and Mounjaro are the approved articles, made under their applications by their sponsors; a vial that shares the molecule shares nothing else. FDA's 2026 letters to research sellers name "Semaglutide" and "Tirzepatide" as unapproved new drugs where the seller's website made them into drugs, and the letter to Peptide Partners, dated August 24, 2026, cites the seller's own efficacy sentence about tirzepatide as part of that evidence.

A research vial is not a substitute for a prescription product, and this site describes only its provenance, never what the molecule does. Retatrutide, the third molecule in this family that people ask about, has never had a compounding window at all, because it has never had an approved product; its status is set out in retatrutide is investigational: what that status means.

Sources

• FDA clarifies policies for compounders as national GLP-1 supply begins to stabilize, FDA, content current as of April 1, 2026
• Tirzepatide shortage declaratory order (PDF), FDA, December 19, 2024
• FDA warns 30 telehealth companies against illegal marketing of compounded GLP-1s, FDA press release, March 3, 2026
• FDA proposes to exclude semaglutide, tirzepatide, and liraglutide on 503B bulks list, FDA press release, April 30, 2026
• Compounding and the FDA: questions and answers, FDA, content current as of September 16, 2025
• Drugs@FDA: Mounjaro, NDA 215866, FDA
• Drugs@FDA: Ozempic, NDA 209637, FDA
• Semaglutide, PubChem CID 56843331, National Library of Medicine
• Tirzepatide, PubChem CID 166567236, National Library of Medicine
• Warning letter to Peptide Partners LLC, FDA, August 24, 2026
• Warning letter to Gram Peptides, FDA, March 31, 2026