An FDA-approved GLP-1 drug such as Ozempic, Wegovy, Mounjaro or Zepbound has been reviewed by the agency for safety, effectiveness and quality. A compounded version, made by a pharmacy or an outsourcing facility, is not FDA-approved, and the FDA does not verify its safety, effectiveness or quality before it is sold. Copies of semaglutide and tirzepatide were allowed while the approved drugs were on the FDA shortage list; the FDA declared both shortages over in 2024 and 2025, and in August 2026 a federal appeals court upheld those decisions.1,
What FDA approval means
To sell a new drug in the US, a company must send the FDA the evidence from its tests. Approval means the agency has determined that the drug's benefits outweigh its known and potential risks for the intended patients, and it generally expects results from two well-designed clinical trials. Generic drugs are also FDA-approved, after showing therapeutic equivalence to the brand-name drug; compounded drugs are not generics.4,
What compounding is: the 503A and 503B routes
Compounding means a pharmacist or doctor combines, mixes or alters ingredients to create a medication. It serves patients who cannot use an approved product, for example because of an allergy to a dye or an inability to swallow tablets, and the FDA says compounded drugs should only be used when an approved drug cannot meet a patient's needs. US law sets out two routes, named after sections of the Federal Food, Drug, and Cosmetic Act.10,
| Rule | Section 503A | Section 503B |
|---|---|---|
| Who compounds | A licensed pharmacist in a state-licensed pharmacy or federal facility, or a physician | An outsourcing facility, a category created in 2013 |
| Main oversight | State boards of pharmacy | The FDA, which inspects on a risk-based schedule |
| Good manufacturing practice (CGMP) rules | Do not apply | Apply |
| Copies of approved drugs | Not regularly or in inordinate amounts, unless a prescriber documents a significant difference for an identified patient | Not allowed unless the approved drug is on the FDA shortage list |
| FDA-approved | No | No |
Why compounding surged during the shortages
The FDA added Wegovy to its drug shortage list in March 2022, Ozempic in August 2022, Mounjaro in December 2022 and Zepbound in April 2024, and attributed the shortages to increased demand. While a drug is on that list, the legal bar on compounding copies is suspended, so pharmacies and outsourcing facilities that met the other conditions could make their own versions.10,
Cost mattered too. University of Colorado researchers wrote that supply problems, high costs and limited insurance coverage together created a robust market for compounded GLP-1 drugs. The American Diabetes Association said the shortages in part led to compounded versions being produced and marketed, and that these continued to be heavily marketed even as the shortages resolved.15,
How the shortages ended, and what the courts decided
The FDA first declared the tirzepatide shortage resolved on October 2, 2024. After the Outsourcing Facilities Association and a compounding pharmacy sued, the agency re-evaluated and confirmed the decision on December 19, 2024, giving state-licensed pharmacies until February 18, 2025 and outsourcing facilities until March 19, 2025 to stop making copies. It declared the semaglutide shortage resolved on February 21, 2025, with end dates of April 22, 2025 for pharmacies and May 22, 2025 for outsourcing facilities.2,
The same plaintiffs challenged both decisions. A federal district court in Texas refused to block them in March and April 2025 and later ruled for the FDA. On August 27, 2026, the Fifth Circuit affirmed in two unpublished opinions, finding that any failure to use notice-and-comment procedures was harmless and that the shortage decisions were not arbitrary or capricious. As of the FDA's April 2026 update, neither drug was on the shortage list.2,
What compounders may still do
- A 503A pharmacy may compound for an individual patient on a prescription. It may not regularly or in inordinate amounts make what are essentially copies of an approved drug, unless the prescriber determines and documents that a change produces a significant difference for that patient.
- The FDA has said it does not intend to act against a pharmacy that fills four or fewer prescriptions of such a copy in a calendar month.
- Adding an ingredient does not automatically make a product different: the FDA may treat semaglutide plus vitamin B12 (cyanocobalamin) as essentially a copy when it is given the same way and both ingredients are within 10% of the strengths of commercially available products.
- Outsourcing facilities may compound from bulk ingredients only if the substance is on the 503B bulks list or the drug is on the shortage list, and as of April 2026 semaglutide and tirzepatide were on neither. In April 2026 the FDA proposed keeping them and liraglutide off the bulks list, finding no clinical need. Comments were due by July 30, 2026, ahead of a final decision.
- Companies may not claim that compounded products are generic versions of, or the same as, FDA-approved drugs, or that they are clinically proven, the FDA said in February 2026.2,
6, 7, 8
The FDA's safety concerns
Dosing errors. In 2024 the FDA noted that approved semaglutide injections came in pre-filled pens with standard concentrations, while compounded versions were offered in various containers, including multiple-dose vials, at concentrations that varied by compounder. It reported patients drawing up five to 20 times their intended dose, and clinicians miscalculating conversions between measurement units, leading to five to 10 times the intended dose. Reported harms included vomiting, fainting, dehydration, acute pancreatitis and gallstones, and some patients needed hospital care.5
Salt forms. Some compounders have used semaglutide sodium or semaglutide acetate. The FDA says these are different active ingredients from the one in the approved drugs, that it does not know whether they have the same chemical and pharmacological properties, and that it is not aware of any lawful basis for using them in compounding.3
Added vitamins. In a September 18, 2026 warning letter to a Texas compounding pharmacy, the FDA said tirzepatide with niacinamide and semaglutide with cyanocobalamin appeared to be essentially copies of approved drugs. It said the volume produced suggested the claimed differences were pretextual, noted "significant difference" statements repeated word for word across many prescriptions, and said products meant to be sterile were made under insanitary conditions. A 2026 study of 33 compounded products advertised online found that 48% combined semaglutide or tirzepatide with ingredients such as cyanocobalamin, glycine, niacinamide, docusate or ondansetron, and its authors saw little justification for adding nutrients.9,
Adverse event reports. As of May 31, 2026, the FDA had received 990 adverse event reports associated with compounded semaglutide and more than 730 with compounded tirzepatide. Federal law does not require state-licensed pharmacies that are not outsourcing facilities to report adverse events to the FDA, so these are likely underreported, and it is not always possible to tell whether the drug caused a reported problem.3
Compounding did not stop when the shortages ended. In a secret-shopper study run from August to October 2025 in West Virginia and Oklahoma, 42 of 75 weight-loss clinics and medical spas offering compounded GLP-1 drugs (56%) offered products combined with B vitamins, and 4 of 21 supplying compounders checked were not licensed for sterile compounding.15
Outside the US
In the UK, unlicensed medicines ("specials") may be supplied only for the special clinical needs of an individual patient, not where an equivalent licensed medicine can meet those needs, and cost or convenience do not count. When a licensed product is unavailable, an unlicensed equivalent may be supplied as a temporary measure, but the MHRA says this does not justify long-term supply and should stop once the licensed product is back. Particular specials may not be advertised.12
That rule comes from Article 5(1) of the EU medicines directive, which lets member states exempt medicines supplied, on a healthcare professional's order, for an individual patient's special needs. During the EU's GLP-1 shortages, which began in 2022, EU regulators helped redistribute stock between member states, asked manufacturers to increase capacity and asked prescribers to keep to authorised uses, while warning that high demand had attracted criminal activity and raised the risk of falsified products.12,