Zepbound
tirzepatide · Eli Lilly
Form
Injectable pen (subcutaneous)
Frequency
Once weekly
Available Doses
FDA Approval Date
November 8, 2023
Mechanism
Dual GLP-1 + GIP receptor agonist
Manufacturer
Eli Lilly
Cost
Self-Pay
$499/mo flat (all doses) via LillyDirect
With Savings Card
$25/mo for commercially insured patients
List Price
~$1,086/mo
LillyDirect self-pay recently updated to $499/mo flat rate for all doses.
Side Effects
| Side Effect | Rate | Source |
|---|---|---|
| Nausea | ~28% | SURMOUNT-1, 15mg dose |
| Diarrhea | ~23% | SURMOUNT-1, 15mg dose |
| Vomiting | ~12% | SURMOUNT-1, 15mg dose |
| Constipation | ~11% | SURMOUNT-1, 15mg dose |
| Injection site reactions | ~3.2% | SURMOUNT-1 |
| Hair loss | ~5% | SURMOUNT-1 |
Source: SURMOUNT-1 Phase 3 Trial, tirzepatide 15mg, 72 weeks
Weight Loss Results
SURMOUNT-1
~22.5%
72 weeks · Completers analysis
Tirzepatide 15mg vs placebo. Highest weight loss of any single-agent GLP-1 class drug.
SURMOUNT-1
~20.9%
72 weeks · Treatment regimen (ITT)
Treatment regimen estimate — all randomized patients.
How It Works
Zepbound activates both GLP-1 and GIP receptors — two key incretin hormones involved in appetite regulation and metabolism. GLP-1 activation reduces appetite, slows gastric emptying, and improves insulin sensitivity. GIP activation adds complementary metabolic benefits including enhanced fat breakdown and additional appetite suppression. The dual mechanism is why Zepbound achieves higher weight loss than GLP-1-only drugs.
Mechanism: Zepbound (tirzepatide) is the first FDA-approved dual incretin agonist, activating both GLP-1 and GIP receptors. This dual mechanism provides enhanced metabolic effects compared to GLP-1-only drugs, leading to the highest weight loss seen in any single-agent GLP-1 class medication.
Who It's For
Indication
Chronic weight management (obesity or overweight with comorbidities)
Adults with obesity (BMI ≥30) or overweight (BMI ≥27) with at least one weight-related condition. Best for patients who need maximum weight loss and are comfortable with weekly injections. Lilly recommends patients may later switch to Foundayo for oral maintenance.
Food & Water Restrictions
✅ No Restrictions
This medication can be taken at any time of day, with or without food and water.
Switching Guides
Comparisons
Medical Disclaimer: This information is for educational purposes only and does not constitute medical advice. Clinical trial data referenced comes from published studies and FDA prescribing information. Side effect rates are from specific clinical trials and may not reflect real-world experience. Always consult your healthcare provider before starting, stopping, or switching any medication.