Common questions
What is the cagrilintide + retatrutide stack?
It is a two-compound research protocol that pairs cagrilintide (an amylin analog that signals fullness through the hindbrain) with retatrutide (a triple GLP-1 / GIP / glucagon agonist). Together they cover four receptor pathways. No clinical trial has tested the exact combination, but the closely related CagriSema (cagrilintide + semaglutide) Phase 3 trial showed that adding amylin to a GLP-1 backbone improves weight loss.
What is 'cag peptide' or 'reta/cag'?
Cag is short for cagrilintide. Reta/cag (or reta-cag) is shorthand for this two-compound stack. Supplier blend names like ma-3rt/cag, fg3-r/cag, GLP-3/cag, 3R + cagri, and AO-3RT/cag all refer to a retatrutide + cagrilintide pre-blend. The mg breakdown on the actual vial label is what matters — the brand name is just supplier shorthand.
How much cagrilintide do you take with retatrutide?
Most community protocols start cagrilintide at 0.25 mg/week once retatrutide is established, then step up every 4 weeks to 0.5, 1.0, 1.7, and 2.4 mg/week. Retatrutide titrates separately from 2 mg up to 12 mg/week.
What is in a 12.5 mg / 2.5 mg reta/cag blend vial?
A standard 5:1 pre-blend contains 12.5 mg retatrutide + 2.5 mg cagrilintide = 15 mg total in one vial. Reconstituted with 2.5 mL bacteriostatic water, this gives 5.0 mg/mL retatrutide + 1.0 mg/mL cagrilintide. A 0.40 mL draw delivers 2.0 mg reta + 0.4 mg cag.
Open the reconstitution calculator →How do you reconstitute the 12.5 mg / 2.5 mg reta-cag blend?
Add 2.5 mL of bacteriostatic water to the 15 mg total pre-blend vial. Inject the BAC water slowly down the inside of the glass — never aim it at the powder. Swirl gently for 30–60 seconds. Do not shake. The resulting concentration is 5.0 mg/mL retatrutide + 1.0 mg/mL cagrilintide. Use within 28–30 days when stored at 2–8 °C.
Open the reconstitution calculator →Should I use a pre-blended vial or separate vials?
Pre-blend is simpler — one injection, one reconstitution, one math step. The trade-off is the fixed 5:1 ratio: you cannot raise one compound without raising the other. Separate vials are better for staggered titration (start retatrutide alone first, then add cagrilintide at Week 9) and for users who have GI sensitivity. For most first-time stack users, separate vials are the safer pick.
Open the reconstitution calculator →Can you take cagrilintide and retatrutide together?
Yes — both compounds are dosed once weekly and the schedules line up well. Same day at different injection sites is standard. The catch is that both slow digestion, so GI side effects can stack. Run retatrutide alone for the first 8 weeks, then add cagrilintide at the lowest dose (0.25 mg). Step both compounds up slowly.
What is the starting dose for cagrilintide when stacking with retatrutide?
0.25 mg/week is the standard starting dose for cagrilintide in a staggered protocol. Hold for at least 2 weeks before stepping up. The titration ladder is 0.25 → 0.5 → 1.0 → 1.7 → 2.4 mg/week, with each step usually held 2–4 weeks. Drop back a step if GI side effects are intense.