Tirzepatide
Metabolic & weight lossAlso known as: Mounjaro, Zepbound, GIP / GLP-1 dual agonist, LY3298176
A dual GIP and GLP-1 receptor agonist approved for type 2 diabetes and weight loss, sold as Mounjaro and Zepbound.
2.What it is / mechanism
Tirzepatide switches on two gut hormone receptors at once, and . Together they lower appetite, slow stomach emptying, and improve how the body handles blood sugar. Hitting both receptors appears to drive more weight loss than a GLP-1 drug alone. It is approved by the FDA for type 2 diabetes (Mounjaro) and weight loss (Zepbound). A fatty acid chain gives it a of about 5 days, which allows once weekly dosing.s1, s3
3.What the evidence supports
- Strong human dataProduces very large weight loss in people with obesity, around 21 to 23 percent of body weight at the higher doses over about 72 weeks.s1
From the SURMOUNT trials. In a head to head study it beat semaglutide for weight loss.
- Strong human dataLowers blood sugar in type 2 diabetes.s2
Its original approved use, from the SURPASS trials.
4.Dosing
| Route(s) | subcutaneous, once weekly |
|---|---|
| Typical range | Start 2.5 mg weekly, which is a starter dose to let the gut adjust, not the target. Then step up every 4 weeks through 5, 7.5, 10, 12.5, and up to 15 mg as needed. |
| Frequency | Once weekly |
| Half-life | 5 days |
| Cycle guidance | Titrated up in 2.5 mg steps, then used continuously. |
| Notes | The slow limits nausea. With a around 5 days, tirzepatide builds up over about a month before it levels off, which is why each step is held for 4 weeks. See the plot below. Like others in this class, it slows stomach emptying and can change how fast other swallowed medicines are absorbed. |
A dose is only as good as the draw. Which syringe you need depends on how much water you mixed with, and the most common gear mistakes (a 0.5 mL syringe that cannot hold the dose, a mixing barrel that ships without needles, sizing up a needle because of body fat) are all avoidable. See what to buy: syringes, needles, and the rest of the kit.
Saturation plotter
Adjust the protocol to see how Tirzepatide builds up in the blood over a cycle and whether it reaches a steady-state plateau.
Blood level over time
Level (mg)Steady-state avg
5.2 mg
Peak / trough
8.1 / 3.1
Time to ~90% saturation
2.4 wk
Saturation at cycle end
100%
Teaching model that assumes even dose spacing, instant absorption, and single compartment clearance. An educational estimate, not a clinical PK simulation or dosing advice.
5.Reconstitution
| Vial sizes | 10 mg, 20 mg, 30 mg |
|---|---|
| Diluent | Bacteriostatic water for multi dose vials, or sterile water for single use |
| Concentration | Example: a 30 mg vial plus 1.5 mL of water gives 20 mg/mL, so a 5 mg dose is 0.25 mL, which is 25 units on a U-100 syringe. Research vials vary widely, so check your label. |
| Notes | The approved products come as prefilled pens or single dose vials with their own instructions. Research material is sold as lyophilized vials in many sizes. |
Reconstitution calculator
Pick your vial size and how much water you add to see the draw volume and syringe units for a dose. Open the full calculator →
Inputs
Which do you know?
You want a set amount of compound. We show how many units to draw on the syringe.
Reminder: 1 mg = 1,000 mcg
Total amount stated on the vial, e.g. 5 mg.
How much diluent you draw into the vial.
Check this before you read the result. 1 mg = 1,000 mcg, so picking the wrong one is a 1,000x error, not a rounding error.
Result
Draw to
100 units
= 1 mL on a U-100 syringe
Over 50 units, so this needs a 1 mL syringe. A 0.5 mL holds 50. Mixing with about 0.9 mL of water would bring it back inside a 0.5 mL, which is easier to read.
Easy draw: this dose comes out to a clean 100 units.
Aim for a dose that lands on an even number of units, like 10, 20, or 50. It is easier to draw accurately and to remember, and it keeps you off awkward repeating decimals.
- Concentration
- 5,000 mcg/mL
- Per unit
- 50 mcg / unit
- Doses per vial
- 2
Your settings live in the address bar, so a pasted link opens this calculator exactly as you left it.
Educational estimate only. Not medical or dosing advice. Verify every calculation independently before use.
6.Storage & stability
Lyophilized (dry)
| Temp | Freeze for long term storage, or 2 to 8 short term |
|---|---|
| Shelf life | Many months when frozen |
| Notes | Keep dry and out of light. If you have an approved product, follow its own storage instructions. |
Reconstituted
| Temp | 2 to 8 (refrigerated) |
|---|---|
| Shelf life | About 2 to 4 weeks |
| Notes | Do not freeze after mixing. Discard if cloudy or discolored. |
7.Reported side effects
- SeriousAcute pancreatitis(rare)s3Seek care for severe, lasting abdominal pain.
- WarningGallbladder problems, including gallstones(uncommon)s3Rapid weight loss can raise the risk of gallstones.
- CautionNausea(common)s1The most common effect, worst in the days after a dose increase, then it eases.
- CautionVomiting, diarrhea, or constipation(common)s1
- InfoReduced appetite(common)s1Expected, and part of how the drug works.
8.Interactions & stacking risks
Tirzepatide can make the pill less reliable, especially around a dose increase. A backup method or a non oral option is advised for the first weeks and after each step up.
Raises the risk of low blood sugar. These medicines may need to be lowered under medical supervision.
Tirzepatide slows stomach emptying, which can change how quickly swallowed drugs are absorbed.
- WarningOther GLP-1 or incretin drugs (semaglutide, retatrutide)
Do not combine drugs in this class. Using more than one at once stacks the gut effects and risks with no proven benefit.
9.Contraindications / who should avoid
- SeriousPersonal or family history of medullary thyroid cancer, or MEN2
Carries an FDA boxed warning based on thyroid C cell tumors seen in rodents. No clear human cases, but the warning stands.
- SeriousPregnancy or breastfeeding
Not for use in pregnancy. It is generally stopped well before trying to conceive.
- WarningHistory of pancreatitis
A possible pancreatitis signal means extra caution.
10.COA & purity notes
| Common adulterants | underdosed or mislabeled research vials, research tirzepatide sold without the controls of the approved product, the wrong salt form sold as the active drug, giving less real drug than the label suggests |
|---|---|
| Mislabeling | There are FDA approved products made to pharmaceutical standards. Research or compounded vials are not held to the same controls, so a recent third party COA matters. |
| Notes | Tirzepatide has approved versions (Mounjaro, Zepbound). Research or compounded material is not the same product. |
11.Sources
- [s1]Diabetes, Obesity and Metabolism (2025). Tirzepatide for obesity: weight reduction and tolerability across the SURMOUNT trials. rct link
- [s2]The Lancet / New England Journal of Medicine (2021). Tirzepatide for type 2 diabetes (SURPASS program). rct
- [s3]U.S. FDA / Drugs.com (2024). Tirzepatide prescribing information and drug overview. regulatory link
Last reviewed 2026-07-07 · status: reviewed