Half-lifeAbout 5 days (FDA label: about 5–6 days in people with obesity)
Vial sizes5 mg, 10 mg, 15 mg, 20 mg, 30 mg, 60 mg
The simple version
What it does
It makes you feel full sooner so you eat less, and it lowers blood sugar.
How people take it
A shot under the skin once a week, starting at 2.5 mg and rising to 5, 10 or 15 mg.
Know this
Nausea and other stomach side effects are common, especially after each dose increase.
What it is
Tirzepatide is a lab-made peptide that acts like two gut hormones, GIP and GLP-1, at once. It's the active drug in Mounjaro (for type 2 diabetes) and Zepbound (for weight loss and sleep apnea). You take it as a shot once a week.
How it works
After you eat, your gut releases two hormones that tell your brain you're full, slow your stomach down and help your body release insulin when blood sugar is high. Tirzepatide keeps both signals on all week. Most people feel full sooner, think about food less and eat less, and blood sugar drops too.
FDA-approved for: Type 2 diabetes (2022, Mounjaro); chronic weight management (2023, Zepbound); obstructive sleep apnea with obesity (2024)
What people use it for
Weight loss
Blood sugar control in type 2 diabetes
Sleep apnea (breathing pauses during sleep) with obesity
Constant food thoughts (food noise) and cravings
The evidence
FDA-approved
Strong. In SURMOUNT-1, adults with obesity on 15 mg a week lost about 21% of their body weight over 72 weeks versus about 3% on placebo, and in SURPASS-2 people with type 2 diabetes got better blood sugar and more weight loss than on semaglutide 1 mg. Like all drugs in this group, weight tends to come back after stopping, and stomach side effects are common while the dose goes up.
Same day each week, any time of day, with or without food
Cycle
Ongoing. Start at 2.5 mg for 4 weeks, then add 2.5 mg no faster than every 4 weeks
Route
Subcutaneous injection (belly, thigh or upper arm)
Why: It takes about 5 days for your body to clear half of it, so one shot a week keeps levels steady. 2.5 mg is only a starter dose to let your stomach adjust. The ongoing doses are 5, 10 or 15 mg; for sleep apnea it's 10 or 15 mg.
Type 2 diabetes (Mounjaro label)
Label dose
Dose
2.5 mg rising to 5–15 mg
How often
Once a week
When
Same day each week, any time of day
Cycle
Ongoing. Same 2.5 mg steps every 4 weeks or more, top dose 15 mg
Route
Subcutaneous injection
Why: Same drug, same schedule. You only step up as far as you need for blood sugar control and as far as your body handles it.
Low-dose maintenance
Reported
Dose
2.5–7.5 mg
How often
Once a week
When
Same day each week
Cycle
Ongoing, often after reaching a goal weight
Route
Subcutaneous injection
Why: Some people stay on the lowest dose that keeps their appetite in check, to cut side effects and cost. Nobody has tested whether this keeps weight off.
Step-up schedule
Weeks
Dose
1–4
2.5 mg once a week (starter dose only)
5–8
5 mg once a week (first possible maintenance dose)
9–12
7.5 mg once a week, if more effect is needed
13–16
10 mg once a week
17–20
12.5 mg once a week
21 on
15 mg once a week (maximum). Every step is optional: stay on any dose that works.
Start at the low end, and change one thing at a time. If you take medication or have a health condition, check with a doctor first.
We may earn a commission from these links. Counts include one syringe and two swabs per dose.
Stay safe
Side effects
Nausea, diarrhea, vomiting or constipation (very common, worst after each dose increase)
Stomach pain, indigestion, burping
Low appetite and tiredness
Reactions where you inject
Dehydration from vomiting or diarrhea, which can strain your kidneys
Gallbladder problems, including gallstones
Pancreatitis, an inflamed pancreas (rare): severe belly pain that spreads to your back
Low blood sugar if you also take insulin or sulfonylureas
Thinning hair during fast weight loss
Losing muscle along with fat if you skimp on protein and strength training
Skip it if
You or a family member had medullary thyroid cancer or MEN 2 (boxed warning: it caused thyroid C-cell tumors in rats)
Pregnant, trying to get pregnant, or breastfeeding
Past pancreatitis
Severe slow stomach emptying (gastroparesis)
Type 1 diabetes (it doesn't replace insulin)
Surgery or a scope procedure (endoscopy) coming up soon: tell the doctor, because food may still be in your stomach
Interactions
Birth-control pills: may work less well. The label says use a backup or non-pill method for 4 weeks after starting and after each dose increase
Insulin or sulfonylureas: higher chance of low blood sugar; doses often need to come down
Other GLP-1 drugs (semaglutide, liraglutide, retatrutide): don't combine
Pills that need exact levels (like the blood thinner warfarin): a slower stomach can change how they absorb
Get help right away for swelling of the face or throat, trouble breathing, chest pain, or a spreading, hot, red injection site.
Storage & legal
Storage
Pharmacy pens and vials: fridge, or room temperature (up to 30 °C) for up to 21 days. Powder: fridge or freezer. Mixed: fridge, use within about 4 weeks. Never freeze it once mixed.
Legal status
FDA: FDA-approved (Mounjaro, Zepbound). Compounded versions are not FDA-approved.
Sport (WADA): Not on the WADA Prohibited List.
Common questions
Is it stronger than semaglutide?
On average, yes. In trials, people lost more weight on tirzepatide. But everyone's different, and some people do better on one than the other.
What if I miss a dose?
The label says take it within 4 days of the day you missed. If more than 4 days have passed, skip it and take the next one on your usual day.
Do I have to reach 15 mg?
No. 5, 10 and 15 mg are all ongoing doses. Many people stay on 5 or 7.5 mg if their appetite is under control.
Can I switch from semaglutide?
People do, usually with a prescriber. A common approach is to start on a lower tirzepatide dose instead of jumping to the top, since side effects can flare.
Sources
Zepbound (tirzepatide) injection, US prescribing information. Eli Lilly; DailyMed, 2026. Source
Mounjaro (tirzepatide) injection, US prescribing information. Eli Lilly; DailyMed, 2026. Source
Jastreboff AM, et al. Tirzepatide Once Weekly for the Treatment of Obesity. N Engl J Med. 2022;387(3):205-216. PubMed 35658024
Frías JP, et al. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes. N Engl J Med. 2021;385(6):503-515. PubMed 34170647