Tirzepatide
A once-weekly dual GIP and GLP-1 agonist; on average more weight loss than semaglutide.
FDA-approved: Zepbound (weight, sleep apnea), Mounjaro (type 2 diabetes).
Used for
- Weight loss
- Type 2 diabetes
- Obstructive sleep apnea
How it works
Adds GIP to GLP-1 action; GIP seems to improve fat handling and tolerance of GLP-1 effects.
Half-life: about 5 days
What the research shows
- SURMOUNT-1 (72 weeks): average weight loss 15.0% on 5 mg, 19.5% on 10 mg and 20.9% on 15 mg vs 3.1% on placebo.
Dosing
Dosing isn’t listed on the public site. In the app, each published option is shown with its source (a drug label, a clinical guideline, a trial or community reports) and can be turned into a protocol you review.
Work out the units to draw for your vial →Side effects
- Nausea, especially after a dose step
- Constipation or diarrhea
- Reflux, burping
- Lower appetite and thirst: dehydration risk
Cautions
- Not for anyone with a personal or family history of medullary thyroid cancer or MEN2.
- Pancreatitis and gallbladder problems are uncommon but reported; severe belly pain needs urgent care.
- Rapid weight loss costs muscle too: keep protein high and keep lifting.
- Stop before planned surgery or sedation per your doctor (slower stomach emptying).
- Can make birth control pills less reliable after starting and after each dose step.
- Don’t mix it with vitamin B12 in one vial: Lilly found a new impurity, at substantial levels, in compounded tirzepatide + B12 products, made by the two reacting (Jordan 2026, Expert Opin Drug Saf, PMID 42010938). Its health effect is unknown, and Lilly sells the brand drug.
Storage
Unmixed or unopened: Fridge (2–8 °C) in the carton. Never freeze; protect from heat and light. A single-dose pen or vial may stay out up to 30 °C for a total of 21 days.
Mixed or in use: An opened multi-dose vial or KwikPen: fridge or up to 30 °C; throw it away 30 days after first use or after 4 weekly doses, even if some is left. Unopened ones out of the fridge: 30 days.
From the Zepbound (Eli Lilly) label.
Stability once mixed
Built to last, with a fatty-acid side chain and a modified backbone, yet the label still says throw out an opened vial or pen 30 days after first use. A vial you mix yourself is a different formulation (no pen buffer), so those days are the pen’s, not yours.
Heat, shaking, freezing a mixed vial, light and many needle punctures all speed breakdown. Toss it if it turns cloudy, grows specks or changes color.
One storage test
Fridge (2 °C): 94% left at day 15, 92% at day 61, 40% at day 113.
Room (about 24 °C): 98% at day 7, 95% at day 15, 40% at day 31.
One vial in the fridge and one at room temperature per peptide, mixed with bacteriostatic water (0.9% benzyl alcohol), kept dark, measured by UV light absorbance (a rough proxy, not a purity test). Vendors and lots not named; not peer reviewed. A single test, not a use-by date. Peptide Critic with Analytical Formulations, Apr 2026
Interactions
It slows stomach emptying. If you use birth-control pills, switch to a non-oral method or add a barrier method for 4 weeks after starting and for 4 weeks after each dose increase.
With insulin or a sulfonylurea it can cause low blood sugar; the label suggests considering a lower dose of those drugs when starting.
For pills that need a steady level or have a narrow safe range (warfarin is the label’s example), the label says to monitor.
Not a full list. Tell your doctor and pharmacist everything you take.
More in Weight & metabolic
Reference only, not medical advice. Written for this app from the cited research. Doses marked community-reported are not from trials.