Retatrutide Dosage Guide & Titration Schedule 2025
Retatrutide Dosage Guide & Titration Schedule 2025
Retatrutide — a once-weekly injectable that targets GLP-1, GIP, and glucagon receptors simultaneously — is emerging as one of the most powerful anti-obesity drugs in development. Phase 2 data showed up to 24 % average body-weight reduction in 48 weeks (NEJM, 2023). But those results came with a clear caveat: dose matters. Starting too high or escalating too quickly can turn manageable nausea into a deal-breaker.
This guide breaks down everything we know about retatrutide dosing so you can have an informed discussion with your healthcare provider.
What you’ll find inside:
- A step-by-step titration schedule from Phase 2 trials
- A printable dosing template you can share with your clinician
- Comparative charts vs. semaglutide and tirzepatide
- Side-effect mitigation strategies you can discuss with your provider
- An evidence-based FAQ
Disclaimer: Retatrutide remains investigational. Final dosing instructions will depend on Phase 3 outcomes and FDA labeling. Always follow your prescriber’s advice.
Why Dosing Strategy Matters
Like other incretin-mimicking drugs, retatrutide’s main adverse events are gastrointestinal: nausea, diarrhea, vomiting, and constipation. In the Phase 2 study, GI symptom rates nearly doubled when participants jumped straight to 8 mg instead of titrating from 1 mg (NEJM, 2023). A “start low, go slow” approach keeps side-effects mild while preserving the dramatic weight-loss effect.
Standard Retatrutide Titration Schedule
The table below synthesizes the protocols used by Eli Lilly (the manufacturer) and those recommended in expert commentaries (IAPAM, 2024; Nicerx, 2024).
| Phase | Weeks | Weekly Dose (mg) | Key Notes |
|---|---|---|---|
| Initiation | 1 – 2 | 1 mg | Assess tolerance; most GI events appear here |
| Early Ramp | 3 – 4 | 2 mg | Increase dose only if nausea is mild or absent |
| Middle Ramp | 5 – 8 | 4 mg | Some protocols adjust ramp speed based on factors such as BMI |
| Late Ramp | 9 – 12 | 6 mg | Escalate in 2 mg steps every 4 weeks |
| Maintenance | ≥ 13 | 8 → 10–12 mg | Target 8–12 mg based on weight-loss response & side-effects |
Dose vs. Results: What the Data Show
| Weekly Dose | Mean Loss @ 24 wks | Mean Loss @ 48 wks | % with ≥15 % Loss at 48 wks |
|---|---|---|---|
| 1 mg | –7.2 % | –8.7 % | 13 % |
| 4 mg | –13.1 % | –17.3 % | 60 % |
| 8 mg | –15.9 % | –22.8 % | 77 % |
| 12 mg | –17.5 % | –24.2 % | 83 % |
Source: NEJM, 2023.
How Retatrutide Stacks Up
| Drug | Receptor Targets | Typical Maintenance Dose | 1-Year Weight Loss | FDA Status |
|---|---|---|---|---|
| Retatrutide | GLP-1 + GIP + Glucagon | 8–12 mg weekly | 22–24 % (Phase 2) | Investigational (Phase 3 ends 2026) |
| Tirzepatide (Mounjaro/Zepbound) | GLP-1 + GIP | 10–15 mg weekly | ~21 % | Approved T2D (Mounjaro); weight-loss (Zepbound) 2023 |
| Semaglutide (Wegovy) | GLP-1 | 2.4 mg weekly | ~15 % | Approved 2021 |
For a deeper dive into semaglutide protocols, read Mastering Ozempic Dosing.
Injection Know-How: Technique & Timing
- Rotate sites (abdomen, thigh, upper arm) to minimize irritation.
- Pick a consistent day/time. Retatrutide’s ~6-day half-life supports once-weekly dosing (NEJM, 2023).
- Use an ultra-fine needle (32–34 G) for comfort.
Managing Common Side Effects
These provider-recommended strategies can help manage common side effects.
| Symptom | Practical Tips |
|---|---|
| Nausea | Eat smaller, lower-fat meals; stay upright after dosing; discuss anti-nausea prescriptions with your provider |
| Diarrhea | Hydrate with electrolyte drinks; reduce high-fiber foods temporarily |
| Constipation | Add soluble fiber; increase water; short daily walks |
| Heart-rate rise | Monitor resting HR; report sustained > 20 bpm increases to your provider |
Tracking Progress: Why a DEXA Scan Matters
Scale weight can’t tell you whether you’re burning fat or losing muscle. A 2023 tirzepatide study reported lean tissue made up roughly 25–40 % of the weight lost (PubMed).
Because incretin-based medications like retatrutide work through similar mechanisms, monitoring body composition is critical. Scheduling a baseline BodySpec DEXA scan before starting — and repeating every 12 weeks — lets you adjust protein intake and resistance training to safeguard muscle.
Ready to get started? Use our location finder to book a scan, or view an example of how to compare providers in Austin.
Counterfeit Alert & Regulatory Timeline
The FDA has already flagged fake retatrutide vials being sold online (GoodRx, 2024). Genuine product is available only through clinical trials. Phase 3 completion is slated for early 2026, with FDA approval possible in 2027.
Frequently Asked Questions
What is the starting dose of retatrutide?
Most trials begin at 1 mg once weekly for two weeks before increasing to 2 mg. Some clinics may start at 2 mg based on individual factors, but 1 mg remains the safest evidence-based entry point.
How fast can I escalate to 8 mg?
Phase 2 protocols increased the dose every four weeks (1 → 2 → 4 → 6 → 8 mg). Slower escalation is fine if side effects persist.
Can I pause dose increases if I feel too nauseous?
Yes. Staying an extra 2–4 weeks at your current dose is common and does not blunt long-term weight loss.
Is retatrutide approved yet?
No. It is in Phase 3 trials. FDA approval could arrive in 2027 at the earliest.
How does retatrutide compare to tirzepatide?
Indirect data suggest slightly greater weight loss with retatrutide (24 % vs. 21 % at ~1 year). Direct head-to-head trials have not yet been published.
Key Takeaways
- Start at 1 mg and escalate every four weeks to reach 8–12 mg.
- Highest-dose studies report up to 24 % body-weight reduction in 48 weeks.
- Combine pharmacotherapy with resistance training and adequate protein to protect muscle.
- Use DEXA scans to track fat vs. lean-mass changes.
- Avoid gray-market products; authentic retatrutide is available only in clinical trials.
Ready to quantify your progress? Book a BodySpec DEXA scan today and see exactly how your body composition changes over time.
