Retatrutide Dosing Protocol — 2026 Guide

The 12-week starter protocol

This is the protocol we recommend to every first-time retatrutide buyer in Canada. It’s a slower, safer titration than what many aggressive protocols online suggest — but it’s the one that produces the lowest reported side-effect rate in our post-purchase surveys, and it matches the TRIUMPH-4 clinical trial ramp-up almost exactly.

Standard 12-week starter protocol

This 12-week ramp uses roughly one 10mg vial per 5 weeks — you’ll need approximately 2-3 vials to complete the full starter protocol. Our Buy-3-Get-1-Free vial bundle covers the entire protocol with a spare vial for continuation into weeks 13+ at maintenance dose.

Reconstitution math for vials

The concentration you end up with depends entirely on how much bacteriostatic water you inject into the vial. There’s no single “correct” concentration — but there’s a smart one, and it’s the one we recommend for the 10mg vials.

Recommended: 10mg + 2ml = 5mg/ml

This gives clean integer syringe measurements at every dose that matters. Every milligram of retatrutide equals 20 units on a standard 0.3ml (30-unit-per-0.3ml) insulin syringe. Simple mental math, low risk of dosing errors.

Alternative: 10mg + 1ml = 10mg/ml

Doubles the concentration, halves the injection volume. Good if you want smaller volume injections or you’re tracking sensitive site reactions. Downside: doubles your risk of syringe measurement error, because each unit represents twice as much peptide.

Alternative: 10mg + 2.5ml = 4mg/ml

Slightly larger volume per dose. Some researchers prefer this because it gives more graduated control over small dose increments (0.5mg steps become clean 12.5-unit marks). But we’ve found buyers get confused with fractional-mg calculations, so we only recommend this for experienced protocol runners.

Full syringe unit conversion table (5mg/ml concentration)

Advanced protocol for high responders

For the roughly 12% of protocols where the buyer has fully acclimated to 6mg weekly by week 12 with minimal side effects and wants to push further, here’s the aggressive titration we’ve seen work in practice. This is not a recommendation — it’s a documented pattern.

The TRIUMPH-4 trial went as high as 12mg per week. Higher doses have not been studied in Phase 3 and we don’t recommend exceeding 12mg per week for any protocol.

Split-dose protocols (twice-weekly)

Some Canadian buyers report smoother side-effect profiles from splitting the weekly dose into two smaller injections rather than one large weekly injection. Retatrutide has a plasma half-life of approximately 6 days, which means a single weekly injection produces relatively stable serum levels — but the “peak” 24 hours after injection can be uncomfortable for some.

Splitting a 6mg weekly dose into two 3mg injections (Monday morning + Thursday evening, for example) reduces the peak and can smooth out the nausea curve. The total weekly bio-exposure is nearly identical.

Travel-day dosing considerations

Travelling with reconstituted vials across time zones creates two logistical challenges: temperature control and dose timing. Both are solvable, but neither is automatic.

Temperature control

An insulated travel case with 2 small gel packs keeps a reconstituted vial in the 2-8°C safe zone for approximately 24 hours. For longer trips, consider taking your vials un-reconstituted and packing bac water separately — a lyophilized vial handles room temperature for up to 30 days without degradation.

Dose timing across time zones

If you’re travelling Vancouver-to-London (8 hour time shift), don’t reset your injection day to local time. Keep injecting on the same 7-day rhythm from your home time zone. Once you’ve been in the new location for 3+ weeks, you can gradually shift the injection to local morning by moving it 1-2 hours per week.