FDA logs 520 adverse event reports tied to compounded semaglutide

By April 30, 2025, the Food and Drug Administration had received 520 adverse event reports connected to compounded semaglutide, and the agency pointed to that tally as part of its reasoning for enforcement deadlines that forced most compounding pharmacies to stop making copies of the drug ^[1].

The reports came after several years of rapid growth in compounded semaglutide. When the FDA added semaglutide to its drug shortage list, it created a legal opening for compounding pharmacies, both state-licensed 503A pharmacies and larger 503B outsourcing facilities, to produce versions of the drug while Novo Nordisk could not meet demand ^[1]. That compounded product often cost patients between $150 and $400 a month, compared with $935 to $1,349 a month for brand-name Ozempic or Wegovy without insurance, which drove millions of patients toward compounded versions ^[1].

In February 2025, the FDA declared the semaglutide shortage resolved, citing expanded manufacturing by Novo Nordisk and the approval of a higher-dose Wegovy formulation ^[1]. That declaration removed the legal basis that had allowed widespread compounding, and the agency set firm deadlines: April 22, 2025, for 503A pharmacies, and May 22, 2025, for 503B outsourcing facilities, to stop compounding versions of semaglutide considered "essentially a copy" of the approved drug ^[1]. The 520 adverse event reports logged by the end of April 2025 were cited as underscoring the urgency behind those deadlines, though the source notes the figure reflects only reported incidents and likely undercounts actual harm ^[1].

Among the safety concerns tied to compounded semaglutide were dosing errors in which patients administered five to 20 times their intended dose because of confusion between units and milligrams-per-milliliter concentrations, a problem linked to multi-dose vials with varying concentrations rather than the fixed-dose pens used for brand-name products ^[1]. Regulators and pharmacy safety groups also flagged the use of unapproved salt forms, such as semaglutide sodium and semaglutide acetate, which have not been evaluated for safety or effectiveness, unlike the semaglutide base used in FDA-approved products ^[1].

Why it matters for patients

The adverse event count helps explain why the compounding market patients relied on for lower-cost access shrank so quickly after the shortage was declared over. Anyone who was getting compounded semaglutide from a 503A or 503B pharmacy during 2025 may have experienced disruptions in supply or been asked to switch to a different product or dosage form as pharmacies came into compliance with the deadlines ^[1].

The reported dosing confusion also points to a practical difference between compounded and brand-name products: multi-dose vials require patients to calculate their own dose, while auto-injector pens deliver a fixed amount, which the source suggests is one reason for the error reports ^[1]. Patients who used unapproved salt forms were taking products that had not gone through the same FDA safety and effectiveness review as approved semaglutide ^[1].

What happens next

After the April and May 2025 deadlines, industry groups won court injunctions that temporarily protected some 503B facilities from a full shutdown, though the 503A deadline was not affected ^[1]. Enforcement escalated further, with a September 2025 warning letter to Hims & Hers Health and, by March 2026, a coordinated wave of more than 50 warning letters to telehealth firms and compounding pharmacies described as the largest action against GLP-1 compounders in U.S. history ^[1]. On April 30, 2026, the FDA proposed removing semaglutide from the list of substances 503B facilities may use, opening a public comment period through June 29, 2026, a step widely expected to end most remaining compounded semaglutide production ^[1].