Retatrutide Dosage Calculator
Calculate your exact retatrutide dose in units and ml for compounded vials. Triple agonist (GLP-1/GIP/GCGR).
Common: 3mg, 5mg, 10mg, 12mg
What is Retatrutide?
Retatrutide is the first triple hormone receptor agonist, activating three key receptors simultaneously: GLP-1 (glucagon-like peptide-1), GIP (glucose-dependent insulinotropic polypeptide), and the glucagon receptor (GCGR). This triple mechanism of action makes it fundamentally different from semaglutide (GLP-1 only) and tirzepatide (GLP-1 + GIP). The addition of glucagon receptor activation increases energy expenditure and promotes fat oxidation, which contributes to significantly greater weight loss than either single or dual agonist therapies.
In a landmark phase 2 clinical trial published in the New England Journal of Medicine, retatrutide demonstrated unprecedented weight loss results. Participants on the highest dose (12 mg weekly) lost an average of 24.2% of their body weight over 48 weeks, making it the most potent weight loss peptide ever tested in clinical trials. This surpasses the results of both semaglutide (approximately 15-17%) and tirzepatide (approximately 22.5%) in their respective pivotal trials.
Retatrutide is developed by Eli Lilly and is currently in phase 3 clinical trials. It is administered as a once-weekly subcutaneous injection. Compounded retatrutide is available as a lyophilized powder that must be reconstituted with bacteriostatic water before injection. This calculator helps you determine the exact volume to draw for your dose based on your specific vial concentration.
How to Use This Calculator
- 1.Enter your vial size in milligrams. This is the total amount of retatrutide in your vial (printed on the label). Common sizes include 3 mg, 5 mg, 10 mg, and 12 mg.
- 2.Enter how much bacteriostatic water you added (or plan to add) during reconstitution. Your pharmacy or provider will usually specify this amount.
- 3.Select or type your weekly dose. If you are just starting, use 1 mg and follow the titration schedule below.
- 4.Click "Calculate My Dose" and the calculator will show you the exact number of units to draw on your insulin syringe, the concentration, and the injection volume in ml.
Standard Titration Schedule
Retatrutide is always started at a low dose and gradually increased every 4 weeks to minimize side effects from the triple agonist mechanism.
Frequently Asked Questions
How is retatrutide different from semaglutide and tirzepatide?
Retatrutide is a triple agonist that activates three receptors: GLP-1, GIP, and the glucagon receptor (GCGR). Semaglutide is a single GLP-1 agonist, while tirzepatide is a dual GIP/GLP-1 agonist. The addition of glucagon receptor activation in retatrutide increases energy expenditure and fat oxidation, which is believed to contribute to the significantly greater weight loss observed in clinical trials compared to both semaglutide and tirzepatide.
What is the recommended starting dose for retatrutide?
The recommended starting dose is 1 mg once per week for the first 4 weeks. This low starting dose allows your body to adjust to the triple agonist mechanism and minimizes gastrointestinal side effects such as nausea, diarrhea, and decreased appetite. Never start at a higher dose, even if you have prior experience with other GLP-1 medications like semaglutide or tirzepatide.
What are the common side effects of retatrutide?
The most common side effects are gastrointestinal: nausea, diarrhea, vomiting, constipation, and decreased appetite. These are most frequent during the first few weeks and after dose increases, and typically improve over time. Because retatrutide also activates the glucagon receptor, some users may experience a slight increase in heart rate. Eating smaller meals, staying hydrated, and avoiding high-fat foods can help manage symptoms. Contact your healthcare provider if side effects are severe or persistent.
When can I expect to see results with retatrutide?
In phase 2 clinical trials, participants began seeing meaningful weight loss within the first 4 to 8 weeks. By 24 weeks, participants on the highest dose (12 mg) had lost an average of 17% of their body weight. By 48 weeks, average weight loss reached up to 24.2%. Individual results vary based on dose, diet, exercise, and metabolic factors. The most significant results are typically seen after 3 to 6 months of consistent use.
How often do I inject retatrutide?
Retatrutide is injected once per week, subcutaneously (under the skin). You can inject in the abdomen, thigh, or upper arm. Choose a consistent day each week (like Sunday or Monday) for your injection. If you need to change your injection day, ensure there are at least 3 days (72 hours) between doses. Rotate injection sites to avoid irritation.
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Which Weight Loss Peptide is Right for You?
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