Different products, same active ingredient
Brand-name GLP-1s — Mounjaro, Zepbound, Ozempic, Wegovy, Rybelsus, Saxenda, Victoza — are FDA-approved drug products. They went through the FDA's drug-approval process, including bioequivalence and stability data, clinical trials documenting safety and efficacy at specific doses, and ongoing post-marketing surveillance.
Compounded versions of semaglutide or tirzepatide are not FDA-approved drug products. They are preparations made by licensed compounding pharmacies (503A) or FDA-registered outsourcing facilities (503B) that contain the same active pharmaceutical ingredient — but as separately-prepared preparations, not as the FDA-reviewed drug product.
Why the distinction matters
Practically: the FDA-approved versions have a specific labeled formulation (with inactive ingredients chosen for stability), known shelf life under specific storage conditions, and bioequivalence data supporting their dose-response curves. Compounded preparations may have different inactive ingredients, different stability profiles, and have not been individually evaluated for bioequivalence to the brand-name product.
For most patients on legitimate programs with reputable pharmacy partners, the active drug behaves clinically similarly to the brand-name version. But 'similarly' is not 'identically,' and the regulatory framing matters legally and clinically.
When compounded is the right answer
Compounded GLP-1s are the right answer when: (1) the cost differential is large enough to materially affect treatment access, (2) you've selected a provider with documented pharmacy disclosure and CoA availability, (3) your clinical picture is straightforward (no complicating allergies, no unusual dose requirements).
Compounded is not the right answer when: insurance coverage for brand-name product is robust; you have allergies to excipients common in compounded preparations; you have a clinical situation requiring tight bioavailability predictability (e.g., advanced T2D with brittle glycemic control).
What about safety?
Reputable 503A and 503B preparations have safety profiles broadly similar to the brand-name products at equivalent doses, based on aggregate post-market experience and on quality testing of compounded preparations.
Unsafe outliers exist — and have been the subject of FDA warning letters and state pharmacy-board actions — typically in pharmacies that don't perform per-batch sterility and potency testing, or in telehealth programs that source from offshore APIs of unverified provenance. Disclosure of pharmacy partner and CoA availability are the two best practical signals of safety posture.