Tirzepatide
Also known as Mounjaro, Zepbound, GIP / GLP-1 dual agonist, LY3298176
Last reviewed · Awaiting clinical review
Main safety concerns
Well studied and approved, but not for anyone with a personal or family history of medullary thyroid cancer or MEN2. Gut side effects are common during dose increases, and it can make the birth control pill less reliable.
- SeriousAcute pancreatitis
- SeriousAvoid if: Personal or family history of medullary thyroid cancer, or MEN2
- SeriousAvoid if: Pregnancy or breastfeeding
Educational information, not medical advice. If you have symptoms that worry you, contact a clinician or emergency services.
What is known
A dual GIP and GLP-1 receptor agonist approved for type 2 diabetes and weight loss, sold as Mounjaro and Zepbound.
- Status:
- FDA approved for type 2 diabetes (Mounjaro) and weight loss (Zepbound). Research vials are not the approved product.[3]
- Strongest evidence for any claim:
On this page
What it is and how it works
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.[1] [3]
Evidence by claim
Each claim is graded on its own. Tap a grade to see what it does and does not mean.
Produces very large weight loss in people with obesity, around 21 to 23 percent of body weight at the higher doses over about 72 weeks.
Source type: Randomized trial
From the SURMOUNT trials. In a head to head study it beat semaglutide for weight loss.
[1]Diabetes, Obesity and Metabolism 2025 (opens source in a new tab)· Randomized trialLowers blood sugar in type 2 diabetes.
Source type: Randomized trial
Its original approved use, from the SURPASS trials.
[2]The Lancet 2021 (opens source in a new tab)· Randomized trial
Reported side effects
- SeriousAcute pancreatitis(rare)[3]Seek care for severe, lasting abdominal pain.
- WarningGallbladder problems, including gallstones(uncommon)[3]Rapid weight loss can raise the risk of gallstones.
- CautionNausea(common)[1]The most common effect, worst in the days after a dose increase, then it eases.
- CautionVomiting, diarrhea, or constipation(common)[1]
- InfoReduced appetite(common)[1]Expected, and part of how the drug works.
Interactions and combination 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.
Who should avoid it
- 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.
Dosing
Placed after the evidence and risks on purpose. Nothing here is a recommendation for you.
| 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 used in the model | 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. |
For the equipment itself, see syringes, needles, and the rest of the kit.
Saturation model (simplified)
A textbook one compartment model of how Tirzepatide could build up with repeated doses. It is a shape, not a measured blood level. The starting values mirror the table above for illustration only.
Modeled amount in the body over time
Assumes evenly spaced doses, instant absorption, and one compartment first order clearance at the half life you entered. The vertical axis is modeled amount remaining in mg, not a measured blood concentration, and real levels vary between people.
Plateau average (modeled)
5.2 mg
Peak / trough
8.1 / 3.1
Time to about 90% of plateau
2.4 wk
Share of plateau at cycle end
100%
Tirzepatide: in this model the amount reaches about 90% of its plateau after 2.4 weeks, and is at 100% of that plateau when dosing stops at week 16.
Show the modeled values as a table
| Week | Tirzepatide (mg) |
|---|---|
| 0 | 5 |
| 1 | 6.9 |
| 2 | 7.6 |
| 3 | 7.9 |
| 4 | 8 |
| 5 | 8 |
| 6 | 8 |
| 7 | 8 |
| 8 | 8 |
| 9 | 8.1 |
| 10 | 8.1 |
| 11 | 8.1 |
| 12 | 8.1 |
| 13 | 8.1 |
| 14 | 8.1 |
| 15 | 8.1 |
| 16 | 3.1 |
| 17 | 1.2 |
| 18 | 0.4 |
An educational estimate, not a clinical simulation or dosing advice.
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. |
General reconstitution technique
Units and volume arithmetic
Converts between an amount and syringe units for the vial and diluent you enter. It starts empty and does not suggest an amount. Open the full calculator
Result
Fill in steps 1 to 3 to see the arithmetic. Nothing here is a suggested amount.
Settings live in the address bar, so a pasted link reopens this calculator as you left it.
Educational arithmetic only. It does not choose an amount for you and is not medical or dosing advice. Verify every calculation independently.
Storage and stability
Dry powder (lyophilized)
| Temperature | 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. |
After mixing
| Temperature | 2 to 8 (refrigerated) |
|---|---|
| Shelf life | About 2 to 4 weeks |
| Notes | Do not freeze after mixing. Discard if cloudy or discolored. |
COA and 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. |
Sources
[1]Tirzepatide for obesity: weight reduction and tolerability across the SURMOUNT trials
Diabetes, Obesity and Metabolism 2025 (opens source in a new tab)· Randomized trial[2]Efficacy and safety of a novel dual GIP and GLP-1 receptor agonist tirzepatide in patients with type 2 diabetes (SURPASS-1)
The Lancet 2021 (opens source in a new tab)· Randomized trial[3]Tirzepatide prescribing information and drug overview
U.S. FDA / Drugs.com 2024 (opens source in a new tab)· Regulatory record
Last reviewed 7 July 2026 · editorial status: reviewed