Retatrutide is an investigational drug that is not FDA-approved and not available at any pharmacy. It is a triple-hormone agonist in Phase 3 trials from Eli Lilly — the same company that makes Zepbound. This page compares what the trial data shows against Zepbound (tirzepatide), which is available now. All comparisons are cross-trial — no head-to-head study exists.
Zepbound vs Retatrutide: What to Know
Helpful Products for GLP-1 Treatment
Managing your GLP-1 medication is easier with the right tools:
- Sharps container — Essential for safe needle disposal. A sharps container is required for home use.
- Ginger products — Manage nausea with ginger chews or ginger tea.
- Water bottle — Stay hydrated to reduce side effects. A large water bottle helps you track intake.
- Electrolyte packets — Prevent dehydration. Liquid I.V. packets dissolve easily in water.
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Quick Comparison
| Zepbound | Retatrutide | |
|---|---|---|
| Active drug | Tirzepatide | Retatrutide |
| Drug class | Dual GIP/GLP-1 agonist | Triple GIP/GLP-1/Glucagon agonist |
| FDA approval | Weight management (approved) | Phase 3 trials (not FDA-approved) |
| Dosing | Once weekly injection | Once weekly injection (in trials) |
| Status | Available now | Investigational — not available |
| Weight loss | ~21% at max dose | 28.3% at 80 wks (TRIUMPH-1); 30.3% at 104 wks (BMI ≥35 subset) |
Cross-trial comparison only. These numbers come from separate studies with different populations, durations, and designs. They cannot be directly compared.
What Makes Retatrutide Different?
Retatrutide mimics three hormones:
- GLP-1 — signals fullness, slows digestion
- GIP — works with GLP-1 to boost the effect
- Glucagon — increases energy expenditure (burns more calories)
Zepbound uses the first two. Retatrutide adds the third.
Weight Loss Results
From clinical trials (as of May 2026):
- Zepbound: ~21% body weight loss at max dose
- Retatrutide — TRIUMPH-1 (general obesity): up to 28.3% average body weight loss at 80 weeks on 12 mg; a subset with BMI ≥35 who continued to 104 weeks reached 30.3%
- Retatrutide — TRIUMPH-4 (obesity with knee osteoarthritis): up to 28.7% at 72 weeks
- Retatrutide — TRANSCEND-T2D-1 (type 2 diabetes): up to 16.8% at 40 weeks
The 28.7% figure comes from TRIUMPH-4, a specific trial in people with knee osteoarthritis. The broader general-obesity figure from TRIUMPH-1 is 28.3% at 80 weeks. Retatrutide shows stronger results than Zepbound in Phase 3 trials, but these are different trials with different populations. No head-to-head trial exists.
Side Effects
Based on Phase 3 trial data:
Zepbound side effects:
- Nausea
- Decreased appetite
- Diarrhea or constipation
Retatrutide side effects (from trials):
- Nausea
- Decreased appetite
- Increased heart rate (from glucagon component)
- Diarrhea or constipation
- Dysesthesia (tingling or burning sensation) — reported in 20.9% of people at the 12 mg dose in TRIUMPH-1. Most cases were mild and did not cause people to stop the drug.
The glucagon component may cause a slightly higher heart rate, which is being monitored in trials. Tell your doctor if you have heart rhythm concerns.
Availability
Retatrutide is not yet FDA-approved. Three Phase 3 trials have reported positive results (TRIUMPH-1, TRIUMPH-4, and TRANSCEND-T2D-1). More Phase 3 readouts are expected in 2026. The earliest likely FDA filing is late 2026 or 2027, with potential approval in 2027.
Zepbound is available now. Retatrutide is not.
Should You Wait for Retatrutide?
No. If Zepbound is working for you, stick with it. If you are not getting the results you want, talk to your doctor about current options — including adjusting your Zepbound dose or considering other approved GLP-1 medications. If retatrutide becomes available later, you and your doctor can discuss switching then.
See our retatrutide guide for full pipeline details, and Mounjaro vs Retatrutide for the most recently updated comparison page in this cluster.
Cost
No pricing yet for Retatrutide. Likely similar to Zepbound (~$1,060/month). See our Zepbound savings card guide for current Zepbound cost assistance.
FAQ
When will retatrutide be available?
Retatrutide is not yet FDA-approved. As of May 2026, three Phase 3 trials have reported positive results, with more Phase 3 readouts expected in 2026. The earliest likely FDA filing is late 2026 or 2027, with potential approval in 2027.
How much more weight loss does retatrutide offer compared to Zepbound?
TRIUMPH-1 showed retatrutide produced up to 28.3% body weight loss at 80 weeks vs approximately 21% for Zepbound at maximum dose. These are cross-trial comparisons — no head-to-head trial exists — and retatrutide is not yet approved. Individual results may vary.
Does retatrutide have more side effects than Zepbound?
Both drugs cause similar GLP-1 side effects like nausea and decreased appetite. Retatrutide may cause increased heart rate due to its glucagon component, which is not present in Zepbound. Dysesthesia was reported in 20.9% at the 12 mg dose in TRIUMPH-1. This is being closely monitored in trials.
Can I take Zepbound now and switch to retatrutide later?
Possibly, but talk to your doctor. Switching between GLP-1 medications is done clinically, but retatrutide will not be available until at least 2027. If Zepbound is working for you now, there is no urgent reason to plan a switch.
Bottom Line
Retatrutide shows stronger weight loss than Zepbound in Phase 3 trials — up to 28.3% at 80 weeks (TRIUMPH-1) vs around 21% for Zepbound — but it is not FDA-approved and not available. The earliest possible approval is likely 2027. If Zepbound is working for you, stick with it. If you are not getting the results you want, talk to your doctor about current options.
Work with your healthcare provider to determine which medication is right for you. Individual results and experiences vary.
