A compounding pharmacy prepares a medication to order, instead of dispensing a manufacturer’s finished product. US law recognises two kinds: 503A pharmacies, which compound against an individual patient’s prescription, and 503B outsourcing facilities, which compound at larger scale.
The key difference from a branded drug: a compounded product is not FDA-approved. The agency reviewed the original medication, not the compounded version, so quality control rests with the pharmacy that made it.
That difference has produced documented problems. In 2023 the FDA placed 19 peptides in a restricted category, citing safety concerns including immune reactions and impurities.[1] In a July 2024 alert, the FDA warned that dosing errors with compounded semaglutide led some people to take 5 to 10 times the intended dose, with some requiring hospitalisation.[2] A 2024 WHO alert warned of falsified Ozempic found in several countries.[3]
Compounded versions are usually cheaper than branded ones, and are priced by the milligram rather than at one flat monthly rate — see the cost calculator and titration.