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What is Zepbound?
About this page. Written by the GLPInfo editorial team with AI assistance from the official sources listed at the end, and approved by the site owner before publication. It has not been reviewed by a named clinician. Published 7 Sep 2026 · next scheduled review 7 Dec 2026.
This page is information, not medical advice. It never tells you which medicine or dose is right for you: those decisions sit with you and a licensed prescriber. Report suspected side effects to FDA MedWatch. Spotted an error? Tell us.
Zepbound is Eli Lilly's tirzepatide under its weight-management brand: a once-weekly injection FDA-approved for chronic weight management in November 2023, and for obstructive sleep apnoea in adults with obesity in December 2024. It is sold as single-dose vials and as the multi-dose KwikPen.
How it works
Tirzepatide activates both the GIP and GLP-1 receptors, two gut-hormone pathways involved in appetite and blood-sugar regulation, reducing appetite and slowing stomach emptying. It is the same molecule as Mounjaro, which carries the type 2 diabetes indication.
Doses and formats
Treatment starts at 2.5mg weekly and steps by 2.5mg at intervals of at least four weeks to 5mg, 7.5mg, 10mg, 12.5mg or 15mg, with 5mg, 10mg and 15mg the labelled maintenance doses. Single-dose vials are the self-pay format sold through LillyDirect; the KwikPen holds four weekly doses.
What the trials showed
In SURMOUNT-1 (72 weeks, adults with obesity without diabetes), tirzepatide 15mg produced an average body-weight reduction of about 20.9% against 3.1% with placebo. In the SURMOUNT-5 head-to-head against semaglutide, average loss was 20.2% with tirzepatide versus 13.7% with semaglutide at maximum tolerated doses. Averages hide wide individual variation, and trial participants received lifestyle support.
Side effects and safety
The most common side effects are gastrointestinal (nausea, diarrhoea, vomiting, constipation), most often around dose increases. The prescribing information carries a boxed warning about thyroid C-cell tumours seen in rodents and lists pancreatitis, gallbladder disease and hypoglycaemia with certain diabetes medicines among the serious risks. Report suspected side effects to FDA MedWatch.
What it costs today
First-month all-in prices for Zepbound at the 2.5mg starting dose currently start from $299 at LillyDirect across the channels we compare, read 6 Sep 2026. Compare all Zepbound channels or see the 12-month true cost.
Frequently asked questions
Zepbound or Mounjaro: what is the difference?
The same medicine, tirzepatide, under two brands with two indications: Zepbound for chronic weight management and sleep apnoea, Mounjaro for type 2 diabetes. Zepbound is also sold in vials at lower self-pay prices through LillyDirect; Mounjaro is $499 at every dose there.
How much does Zepbound cost without insurance?
From $299 (2.5mg) through $399 (5mg) to $449 (7.5mg and above) at LillyDirect and the telehealth channels that match it, plus the channel's membership fee where there is one. Live comparison.
Is Zepbound covered by Medicare?
Not under Part D for weight management, but eligible Medicare members can obtain the Zepbound KwikPen for $50 a month under the GLP-1 Bridge program to the end of 2027: details.