Retatrutide Dosing: 0.5mg 3x/Week Protocol

Retatrutide is a triple-agonist peptide targeting GLP-1 + GIP + glucagon receptors simultaneously. Phase 2 trials showed up to 24.2% body weight loss in 48 weeks at higher doses — the most potent weight-loss data from any metabolic peptide studied to date.

Retatrutide is not FDA-approved. Everything below reflects published clinical trials and community protocols. This is not medical advice.

Quick Reference: Standard Protocol

Most people start at 0.25 mg for the first week to assess GI tolerance, then increase to 0.5 mg.

For the full retatrutide profile and vendor pricing, see our Retatrutide peptide page.

Cycling Details

The standard cycle is 0.5 mg 3x/week (1.5 mg/week total) for 8 weeks, then 8 weeks off. Some users run goal-oriented cycles — continuing until target weight loss, then cycling off. Maintenance phases may drop to 2x/week (1 mg/week total).

The 3x/week split (vs. single weekly injection used in clinical trials) may provide more stable receptor activation throughout the week.

Routes of Administration

Subcutaneous injection is the only route. Retatrutide cannot be taken orally.

• Sites: Abdomen, thigh, or anywhere with subcutaneous fat
• Volume: 0.1 mL with insulin syringe (29-31 gauge)
• Rotation: Rotate injection sites to prevent lipodystrophy

Reconstitution Quick Reference

Math: 10 mg / 2 mL = 5 mg/mL. For 0.5 mg: 0.5 / 5 = 0.1 mL = 10 units.

Swirl gently — do not shake. Refrigerate at 2-8 C, use within 28 days. For step-by-step instructions and vial size comparisons, see the full Retatrutide Reconstitution Guide.

Where These Numbers Come From

Community doses represent a conservative approach compared to clinical trials.

Phase 2 obesity trial: Escalating weekly doses from 1 mg to 12 mg over 48 weeks. Maximum weight loss: 24.2% at 12 mg/week (Jastreboff et al., 2023).

Phase 2 diabetes trial: Dose-dependent HbA1c reductions — minimum effective dose for meaningful glucose control was 4 mg/week (Rosenstock et al., 2023). Community protocols at 1.5 mg/week fall below this threshold.

Why community doses are lower: No FDA approval means conservative self-titration. Lower doses reduce GI side effects. The clinical trial starting dose (1 mg/week) is already close to the community protocol (1.5 mg/week split 3x). Many see significant effects at these lower levels.

Research Vial Sizing

Larger vials offer better per-mg pricing. Compare current vial options and verified vendors at Best Retatrutide Vendors.

Stacking Protocols

Retatrutide already hits three major metabolic pathways, leaving few complementary targets. Adding other GLP-1 agonists (semaglutide, tirzepatide) is redundant and increases side effects. Stacking with other weight loss peptides is generally unnecessary.

Side Effects & Safety

• Nausea — most common (~33% at high doses), dose-dependent, typically improves over time
• GI effects — vomiting, diarrhea, constipation, slowed gastric emptying (GLP-1 class effects)
• Heart rate changes — transient increases observed in trials, peaked at 24 weeks then declined
• Injection site reactions — mild redness or irritation
• Gallbladder risk — rapid weight loss increases gallstone risk (common with any rapid weight loss method)
• No major safety signals in 48-week trial up to 12 mg weekly
• At community doses (1.5 mg/week), side effects are notably milder than high-dose trial groups

Frequently Asked Questions

What is the standard retatrutide dose for weight loss?

0.5 mg subcutaneously 3 times per week (1.5 mg/week total), in the morning, cycled 8 weeks on / 8 weeks off. This is much lower than the clinical trial max of 12 mg/week.

Why are research vials sold as 12mg, 24mg, or 60mg?

These are total vial contents, not single doses. A 24 mg vial provides 48 doses at 0.5 mg each.

How does retatrutide compare to tirzepatide?

Based on Phase 2 data, retatrutide showed greater weight loss (24.2% max vs ~22% for tirzepatide). Retatrutide is a triple agonist (GLP-1 + GIP + glucagon) while tirzepatide is dual (GLP-1 + GIP).

Is retatrutide FDA-approved?

No — Phase 3 trials are ongoing. All dosing reflects research protocols and community use.

Should I start at 0.5mg or lower?

Many start at 0.25 mg for the first week to assess GI tolerance, then increase to 0.5 mg.

Can retatrutide be taken orally?

No — it's a peptide that would be destroyed by digestive enzymes. Subcutaneous injection only.

Related Guides

• Retatrutide Peptide Page — Vendor pricing, comparisons, and full profile
• Retatrutide Reconstitution Guide — Step-by-step mixing and dilution charts
• Retatrutide Bloodwork Guide — What labs to track and optimal ranges
• Tirzepatide Dosing Guide — Dual agonist alternative
• Semaglutide Dosing Guide — Single GLP-1 agonist reference
• Retatrutide Phase 3 Results — Latest clinical trial updates
• Best Retatrutide Vendors of 2026 — ranked by price, purity testing, and buyer trust
• Calculate Your Retatrutide Cycle Cost — estimate vials needed and total cost for your protocol
• Where to Buy Retatrutide — COA verification, vial sizes, and vendor comparison

References

This article is for educational and informational purposes only. It is not medical advice. Retatrutide is not FDA-approved for any indication. Consult a licensed healthcare provider before using any peptide.