Tirzepatide activates two incretin receptors rather than one: GIP (glucose-dependent insulinotropic polypeptide) as well as GLP-1. It is a single 39-amino-acid peptide engineered to bind both, with a fatty-acid chain that extends its half-life to roughly five days.
In head-to-head and placebo-controlled trials it has produced larger average weight reductions than GLP-1 agonism alone. Why adding GIP activity helps is still debated, since the receptor's role in appetite regulation is not settled. The clinical effect has been replicated across large trials regardless.
How it works
GLP-1 receptor activity accounts for the familiar effects: insulin release when glucose is high, suppressed glucagon, slowed gastric emptying, and reduced appetite through receptors in the brain.
The GIP component adds activity at a second incretin receptor found in the pancreas, in fat tissue, and in the brain. Current thinking is that GIP agonism improves how fat tissue handles nutrients and may independently reduce food intake, though the mechanism is an active research question rather than a settled one.
Regulatory status — United States
Approved by the FDA as a prescription medicine for type 2 diabetes and for chronic weight management. Material sold as a research chemical is not the approved product and is not legal to sell for human use.
Last reviewed 12 Aug 2026. Regulatory positions in this category change frequently; we date this line so you can see how current it is.
What it is studied for
Each entry states the evidence behind it. We do not rank indications by effectiveness — for most compounds here, that would be a claim nobody can support.
Weight management
Clinical trialApproved for chronic weight management.
EvidenceRandomised placebo-controlled phase 3 trial in adults with obesity over 72 weeks.
Type 2 diabetes
Clinical trialApproved for glycaemic control in type 2 diabetes.
EvidenceThe SURPASS phase 3 programme.
Identity and clearance
Molecule
- Class
- Dual GIP and GLP-1 receptor agonist
- Molecular weight
- 4813.5 Da
- Length
- 39 amino acids
A single engineered peptide, not two molecules combined. The C20 fatty diacid chain provides albumin binding and the long half-life.
Pharmacokinetics
Clinical trialAbout five days, so steady state is reached after roughly four weeks of consistent weekly dosing.
Dose protocols reported in sources
Displayed for reference only. Every row says where it came from, and a trial protocol and a community convention are not the same kind of information. None of this is fed into the calculator, and none of it is a recommendation.
| Goal | Dose | Frequency | Route | Units, 5 mg vial | Source | Start this protocol |
|---|---|---|---|---|---|---|
| Trial escalation, weeks 1–4 | 2.5 mg | Once weekly | Subcutaneous | 50 u | Clinical trial | Start this |
| Trial escalation, thereafter | 5 mg – 12.5 mg | Once weekly, raised by 2.5 mg every four weeks | Subcutaneous | from 100 u | Clinical trial | Start this |
| Trial maintenance doses | 5 mg – 15 mg | Once weekly | SubcutaneousThe trial ran separate 5 mg, 10 mg and 15 mg maintenance arms, not a single target dose. | from 100 u | Clinical trial | Start this |
Start this copies a row into a protocol of your own, which you can then edit. Where a source gave a dose range or an ambiguous frequency, those fields arrive empty — we will not pick a number on your behalf.
Calculator
Work out what to draw
Pre-filled with a 10 mg vial as a worked example. These are not recommended values — change them to match the vial in front of you.
Draw to 50 units on a 1 mL U-100 syringe. That is 0.5 mL, containing 2.5 mg of Tirzepatide.
50 units sits exactly on a printed line.
Bioalmanac performs arithmetic on values you enter. It does not recommend doses, schedules or compounds, and nothing here is medical advice. Confirm every calculation against your vial and syringe before drawing, and speak with a licensed healthcare provider.
Open this calculation in the full calculator
Units, concentration, bacteriostatic water — the glossary defines the vocabulary, and a unit is not a fixed volume.
Safety
Reported effects
- NauseaClinical trial
Very common in trials
Dose-related and worst after an increase.
- Diarrhoea, constipation, vomitingClinical trial
Common in trials
- Reduced appetiteClinical trial
Very common
Can be pronounced enough to make adequate protein and fluid intake difficult.
- Gallbladder problemsClinical trial
Uncommon but documented
- PancreatitisClinical trial
Rare
- Loss of lean mass alongside fatClinical trial
Documented in trials
When to stop
- Severe, persistent abdominal pain radiating to the back, with or without vomiting. Seek urgent medical care.
- Persistent vomiting or inability to keep fluids down.
- Upper right abdominal pain, fever, or yellowing of the skin or eyes.
- A neck lump, hoarseness, or difficulty swallowing.
- Any allergic response: rash, hives, facial swelling, or difficulty breathing. Seek urgent care.
- If you become pregnant or are planning to.
Interactions and situations that need care
- Personal or family history of medullary thyroid carcinoma, or MEN 2Avoid
The approved product carries a boxed warning on this basis, following rodent thyroid C-cell findings.
- History of pancreatitisUse caution
Pancreatitis is a documented if uncommon adverse event.
- Pregnancy and breastfeedingAvoid
Not recommended, and the long half-life means stopping well in advance.
- Insulin or sulfonylurea therapyUse caution
Combined glucose-lowering raises hypoglycaemia risk and usually requires the other agent to be adjusted by its prescriber.
- Planned surgery or general anaesthesiaUse caution
Delayed gastric emptying can leave food in the stomach despite standard fasting, which is an aspiration risk. Tell your anaesthetist.
What to expect
- In SURMOUNT-1, mean weight reduction over 72 weeks was about 15% at 5 mg, 19.5% at 10 mg and 20.9% at 15 mg weekly, against 3.1% on placebo.
- Escalation to a maintenance dose takes roughly five months under the trial schedule.
- These are averages under supervised conditions with lifestyle support, not a prediction for an individual.
- As with semaglutide, weight regain after discontinuation is documented.
Storage and handling
- Freeze-dried powder
- Refrigerated at 2–8 °C and protected from light. Keep the powder dry until you are ready to use it.
- After mixing
- Refrigerated at 2–8 °C. Do not freeze. Discard if cloudy or discoloured.
- Long-term, frozen
- Unopened lyophilised powder is stable at −20 °C or colder.
With other peptides
- Semaglutideincompatible
Both act on the GLP-1 receptor. Running them together duplicates a mechanism rather than adding one, and compounds gastrointestinal effects.
- Retatrutideincompatible
Overlapping GLP-1 and GIP agonism. These are alternatives, not a stack.
- Liraglutideincompatible
Tirzepatide already includes full GLP-1 receptor agonism. Adding liraglutide stacks the same mechanism, with the same side effects and no additional benefit.
- Cagrilintidecaution
Plausible on paper, since amylin signalling is separate from both GLP-1 and GIP. No trial has tested it, and stacking three appetite-suppressing mechanisms risks intake falling below what is safe.
- Orforglipronincompatible
Tirzepatide already includes full GLP-1 agonism. Adding orforglipron stacks the same mechanism with the same side effects and no additional benefit.
Checking your vial
Research chemicals carry no manufacturing standard, so what the vial looks like is often the only quality signal available before you use it. More on assessing quality and COAs.
White cake, clear solution
Standard for a correctly lyophilised peptide of this class.
Collapsed cake or discoloured solution
Indicates heat damage or degradation. Do not use.
Questions
- How is tirzepatide different from semaglutide?
- Semaglutide acts on the GLP-1 receptor alone; tirzepatide acts on both GLP-1 and GIP. In trials the dual agonist has produced larger average weight reductions, though the two have different dosing scales and different side-effect profiles.
- Why are tirzepatide vials sold in such large milligram sizes?
- Doses are measured in milligrams rather than micrograms, so a vial covering several weeks holds substantially more compound than a typical research peptide vial. This is also why entering a tirzepatide dose in micrograms by mistake produces an obviously wrong result, and the calculator will flag it.
References
Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1)
New England Journal of Medicine, 2022 · Randomised, double-blind, placebo-controlled phase 3 trial
Adults with obesity, without diabetes · n = 2539 · 5 mg, 10 mg or 15 mg once weekly · 72 weeks
Mean weight change of −15.0%, −19.5% and −20.9% across the three dose arms against −3.1% on placebo. Gastrointestinal events were the most common adverse effects.
10.1056/NEJMoa2206038
Tirzepatide compared with
Tirzepatide vs survodutide
Two dual agonists that picked different second receptors, GIP in one case and glucagon in the other, and that sit at very different stages of evidence.
Semaglutide vs tirzepatide
Both are once-weekly incretin agonists approved for weight management. The difference is how many receptors each one acts on, and what that does to the dosing scale.
Tirzepatide vs retatrutide
Two and three receptors respectively. Retatrutide reported the larger weight reduction; tirzepatide has a completed phase 3 programme and an approval. This is a different kind of claim.
Related compounds
Semaglutide
A long-acting GLP-1 receptor agonist approved for type 2 diabetes and for weight management, dosed once weekly.
Retatrutide
An investigational once-weekly triple agonist acting on the GLP-1, GIP and glucagon receptors. Not approved anywhere.
Liraglutide
The first GLP-1 analogue approved for weight loss. A daily injection, superseded by weekly semaglutide but still the best-documented compound in the class.
Cagrilintide
A long-acting amylin analogue in late-stage trials. It works on a different satiety pathway from the GLP-1 drugs. Which is why it is being developed alongside semaglutide rather than against it.
Next
What to do with Tirzepatide
- Keep a record of itTurn a dose and a schedule into a protocol, then log what you actually take. Tirzepatide is filled in for you.
- See what it costsPer-milligram prices read from vendor sites and confirmed by a person, so vial sizes compare.
- Check a combinationWhat our profiles record about Tirzepatide alongside each other compound — including the pairs where nothing is recorded.
Keep this page honest
If something here is wrong, out of date, or missing a source, tell us and we will fix it and say that we did.
This page is educational. It describes what published research reports, not what you should do. Peptides discussed here are largely not approved for human use, and nothing on Bioalmanac is medical advice. No clinician reviews these pages.
Page last updated 12 Aug 2026