Tirzepatide: what it is, what it costs, and who sells it

Tirzepatide is a synthetic peptide, 39 amino acids long, engineered to activate two separate hormone receptors that the body's own gut hormones normally trigger after eating. FDA has approved two branded products built on it — Zepbound, for chronic weight management, and Mounjaro, for type 2 diabetes — confirmed directly against FDA's own Drugs@FDA record, which lists both products' marketing status as “Prescription.”

A compounded tirzepatide product is a different thing: a pharmacy-prepared version made under a narrow federal exemption (21 U.S.C. §353a) that lets a compounder legally sell a copy of tirzepatide only while Zepbound stays in an FDA-declared shortage. It is not a generic, it is not independently reviewed by FDA the way the branded pens are, and it is the product almost every telehealth provider on the board below actually sells.

Tirzepatide activates two hormone receptors at once — GIP and GLP-1 — rather than the single GLP-1 target semaglutide works on. Activating both slows how quickly the stomach empties, increases insulin release when blood sugar is high, and reduces appetite. In the one randomized trial that put tirzepatide and semaglutide head to head, SURMOUNT-5, 751 adults on either drug at its own maximum dose for 72 weeks lost -20.2% body weight on tirzepatide versus -13.7% on semaglutide — read the full trial breakdown, and how it compares to tirzepatide's own earlier placebo trial (SURMOUNT-1, -20.9% at 15 mg vs. -3.1% placebo), in our full tirzepatide-vs-semaglutide review.

Compounding is a real, legal activity, but it is a narrow one: a pharmacy can only compound tirzepatide because it is the active ingredient in an FDA-approved drug, and it can only sell it in volume while that drug — Zepbound — remains in shortage. FDA declared that shortage resolved in late 2024 and has since narrowed who may keep compounding tirzepatide legally, a moving timeline this site tracks in full detail rather than restating here.

For the complete regulatory timeline, what “essentially a copy” means under the statute, and how the providers on the board below each disclose (or don't) their pharmacy sourcing, see is compounded tirzepatide still legal? and what compounded tirzepatide actually is, both read directly off the statute and FDA's own guidance, not a summary of a summary.

The dominant, dose-related signal on both FDA labels is gastrointestinal: nausea, diarrhea, vomiting, and constipation, concentrated during dose escalation. Zepbound's label reports gastrointestinal adverse reactions in 56% of patients at every dose tested (5, 10, and 15 mg alike) against 30% on placebo — this is what the label's own four-week escalation steps exist to blunt, not eliminate.

This page states the headline finding only. For the full dose-by-dose breakdown across both Zepbound's (obesity) and Mounjaro's (type 2 diabetes) separate label data, discontinuation rates, and the label's own gastric-emptying interaction with oral contraceptives, see our full tirzepatide side-effects review. None of this is a recommendation for or against starting tirzepatide — talk to a licensed clinician about your own situation.