This is a premixed vial of retatrutide (12.5 mg) and cagrilintide (2.5 mg), 15 mg total in a 5:1 ratio. Retatrutide is an experimental weekly shot from Eli Lilly and cagrilintide is one from Novo Nordisk, and neither is approved on its own. The idea copies CagriSema, Novo Nordisk's mix of cagrilintide and semaglutide, but swaps in retatrutide for semaglutide.
How it works
Retatrutide copies three gut hormones: two that cut appetite and help blood sugar (GLP-1 and GIP), and one (glucagon) that may help you burn more energy. Cagrilintide copies amylin, a hormone released with insulin after meals that makes you feel full sooner and slows your stomach. Because amylin works a different way, adding it to a GLP-1 drug gave extra weight loss in CagriSema trials, and the hope is it does the same here.
What people use it for
Weight loss
Appetite control
The evidence
Some human studies
Each drug has strong human data on its own: retatrutide 12 mg cut weight by 24.2% at 48 weeks in an early (phase 2) trial and by 25.0% at 80 weeks (vs 3.9% on placebo) in the 2026 late-stage (phase 3) TRIUMPH-1 trial, and cagrilintide plus semaglutide (CagriSema) cut weight by 20.4% at 68 weeks (vs 3.0% on placebo) in REDEFINE 1. But no human trial has tested retatrutide and cagrilintide together (we found none on PubMed or ClinicalTrials.gov as of October 2026); the only data is one 2026 study in obese rats, where the mix beat either drug alone, and rat results often don't carry over to people. Nobody knows the side effects of two strong appetite drugs taken together.
2.4–14.4 mg of blend a week (2–12 mg retatrutide + 0.4–2.4 mg cagrilintide)
How often
Once a week
When
Same day each week, any time of day, with or without food
Cycle
Ongoing while losing weight, stepping up no faster than every 4 weeks
Route
Subcutaneous injection (belly, thigh or upper arm)
Why: Both drugs last about a week in your body, so one weekly shot keeps levels steady. Dose by retatrutide, the main part. The 5:1 ratio happens to match the trials: 12 mg retatrutide (its top trial dose) brings 2.4 mg cagrilintide (its top trial dose). Slow steps cut nausea. Example: add 2.5 mL of bacteriostatic water to a 15 mg vial. That makes 6 mg/mL of blend (5 mg/mL retatrutide, 1 mg/mL cagrilintide). A 2 mg retatrutide dose is 0.4 mL, or 40 units on a U-100 insulin syringe. A 4 mg dose is 0.8 mL, or 80 units. At 8 mg and up, one vial lasts only one or two weeks.
Step-up schedule
Weeks
Dose
1–4
2 mg retatrutide + 0.4 mg cagrilintide once a week (0.4 mL with the 2.5 mL mix)
5–8
4 mg retatrutide + 0.8 mg cagrilintide once a week (0.8 mL)
9–12
8 mg retatrutide + 1.6 mg cagrilintide once a week (1.6 mL, split into two shots), only if needed and tolerated
13+
Up to 12 mg retatrutide + 2.4 mg cagrilintide once a week, only if needed. Many people stop climbing at the lowest dose that works.
Start at the low end, and change one thing at a time. If you take medication or have a health condition, check with a doctor first.
We may earn a commission from these links. Counts include one syringe and two swabs per dose.
Stay safe
Side effects
Nausea (very common, and likely worse with two appetite drugs)
Vomiting
Diarrhea or constipation
Stomach pain, burping, bloating
Eating too little, dehydration, dizziness
Faster resting heart rate (seen with retatrutide)
Reactions where you inject
Gallstones with fast weight loss
Losing muscle along with fat if you skimp on protein and strength training
Skip it if
You or a family member had medullary thyroid cancer or MEN2 (a warning for this drug type)
Past pancreatitis (inflamed pancreas)
Pregnant, breastfeeding or trying to get pregnant (stop well before)
Type 1 diabetes
Serious stomach problems like gastroparesis (slow stomach emptying)
Gallbladder disease
Past eating disorder
Under 18
Already on semaglutide, tirzepatide or another GLP-1 drug
Interactions
Insulin or sulfonylureas: higher chance of low blood sugar
Pills that need steady absorption (like birth-control pills or thyroid meds): a slower stomach can change how well they absorb
Other GLP-1 or amylin drugs: don't combine
Get help right away for swelling of the face or throat, trouble breathing, chest pain, or a spreading, hot, red injection site.
Storage & legal
Storage
Powder: fridge or freezer. Mixed: fridge, use within about 4 weeks. Don't freeze once mixed.
Legal status
FDA: Not approved. Retatrutide is still in phase 3 trials. Cagrilintide is not approved on its own. This blend has never been studied in people.
Sport (WADA): Not named on the list. Unapproved drugs can fall under S0 (non-approved substances); check before competing.
Common questions
Is this the same as CagriSema?
No. CagriSema pairs cagrilintide with semaglutide and has late-stage (phase 3) trial data. This blend pairs it with retatrutide, a different and stronger drug, and has no human trial data at all.
Can I raise cagrilintide without raising retatrutide?
Not with this vial. The 5:1 ratio is locked. If you feel sick on it, you can't tell which drug is the cause or lower just one.
Why start so low?
Both drugs cause nausea, and two together may cause more. Both were tested in trials with slow steps every 4 weeks, which cut stomach side effects.
Sources
Jastreboff AM, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial. N Engl J Med. 2023;389(6):514-526. PubMed 37366315
Jastreboff AM, et al. Retatrutide, a Triple Hormone Receptor Agonist, for Treatment of Obesity. N Engl J Med. 2026 Sep 29 (online ahead of print). PubMed 42814954
Garvey WT, et al. Coadministered Cagrilintide and Semaglutide in Adults with Overweight or Obesity. N Engl J Med. 2025;393(7):635-647. PubMed 40544433
Frias JP, et al. Efficacy and safety of co-administered once-weekly cagrilintide 2.4 mg with once-weekly semaglutide 2.4 mg in type 2 diabetes: a multicentre, randomised, double-blind, active-controlled, phase 2 trial. Lancet. 2023;402(10403):720-730. PubMed 37364590
Lau DCW, et al. Once-weekly cagrilintide for weight management in people with overweight and obesity: a multicentre, randomised, double-blind, placebo-controlled and active-controlled, dose-finding phase 2 trial. Lancet. 2021;398(10317):2160-2172. PubMed 34798060
Petersen J, et al. Cagrilintide and retatrutide combination therapy enhances weight loss and metabolic outcomes in obese male rats. Nat Metab. 2026 Sep 15 (online ahead of print). PubMed 42744908