Tirzepatide vs. semaglutide: how they compare for weight loss
How tirzepatide and semaglutide work, what head-to-head research shows, side effects, cost and how to choose with your clinician.
If you've looked at online weight-loss programs, you've seen "compounded" tirzepatide and semaglutide. Here's what that word means, what it doesn't, and what to look for in a provider.
What compounding is
Compounding is when a licensed pharmacist prepares a medication for an individual patient, based on a prescription. It has existed for a long time, for example to make a liquid version of a pill or to leave out an ingredient someone is allergic to. Compounded GLP-1 preparations often add an ingredient such as vitamin B12.
What compounded medications are not
- They are not FDA-approved. The FDA does not review them for safety, effectiveness or quality before they're dispensed.
- They are not generics. Generic drugs are FDA-approved copies of brand-name drugs; compounded drugs are not.
- They are not the same as Zepbound®, Mounjaro®, Wegovy® or Ozempic®, and were not studied in those medicines' clinical trials.
The rules have changed
During the GLP-1 shortages of 2022–2024, compounders had wider latitude to make copies of these medicines. The FDA declared the tirzepatide shortage resolved in December 2024 and the semaglutide shortage resolved in February 2025. Since then, compounding pharmacies are generally limited to preparations that meet an individual patient's documented clinical need, and the FDA has warned companies, including in a March 2026 round of 30 warning letters to telehealth firms, against marketing compounded GLP-1s as the same as approved drugs or hiding who actually makes them.
How to choose a safer provider
- A licensed clinician reviews your full health history before prescribing, and you can verify their license.
- The pharmacy is state-licensed and named. You should be able to find out who prepares your medication.
- The company is clear that compounded drugs aren't FDA-approved, and doesn't promise guaranteed results.
- You get ongoing care: dose adjustments, side-effect support and a way to reach a clinician.
- Avoid "research use only" peptides sold without a prescription.
Sources
- U.S. Food and Drug Administration. FDA's concerns with unapproved GLP-1 drugs used for weight loss.
- U.S. Food and Drug Administration. Clarification of policies for compounders as national GLP-1 supply begins to stabilize.
This article is for general information and isn’t medical advice. See our Important Safety Information.
