Research library

Tirzepatide

LY3298176 · Mounjaro · Zepbound

Evidence A · Strong human evidenceApproved medicine

In one line. One of the best-studied weight loss medicines, with large human trials behind its doses.

What it is

Tirzepatide is a man-made peptide that acts like two gut hormones, GIP and GLP-1. These hormones help release insulin after meals and make you feel full. It is injected under the skin once a week.

What is actually known

It has strong human evidence. Large trials tested 5, 10 and 15 mg weekly in thousands of people.

Approved in the US for type 2 diabetes (2022, Mounjaro) and chronic weight management (2023, Zepbound)

At a glance

RouteUnder the skin

How oftenOnce a week

Half-lifeabout 5 days

Peakabout 1 to 2 days

Mix withBacteriostatic water

After mixingRefrigerate 2-8 C, use within 28 days, never freeze

Dose schedule

Product label

Source: Mounjaro and Zepbound prescribing information, section 2 (Dosage and Administration)

Weeks	Dose	How often
1 to 4	2.5 mg	Once a week
5 to 8	5 mg	Once a week
9 to 12	7.5 mg	Once a week
13 to 16	10 mg	Once a week
17 to 20	12.5 mg	Once a week
21 onwards	15 mg	Once a week

The label starts at 2.5 mg for 4 weeks, then raises the dose by 2.5 mg no sooner than every 4 weeks. Usual maintenance is 5, 10 or 15 mg. Many people stay on a lower step if it works.

Mixing and drawing up

Pick your vial size. Water is chosen so every step reads between 2 and 100 units on a U-100 insulin syringe. Every number below is calculated, not typed.

Vial5 mg

Add water1 mL

Strength5 mg/mL

1 unit50 mcg

Dose	Draw	Units	Doses in vial	Used within 28 days
2.5 mg	0.5 mL	50 U	2	2
5 mg	1 mL	100 U	1	1
7.5 mg				Not from this vial: more than the vial holds
10 mg				Not from this vial: more than the vial holds
12.5 mg				Not from this vial: more than the vial holds
15 mg				Not from this vial: more than the vial holds

Vial10 mg

Add water1 mL

Strength10 mg/mL

1 unit100 mcg

Dose	Draw	Units	Doses in vial	Used within 28 days
2.5 mg	0.25 mL	25 U	4	4
5 mg	0.5 mL	50 U	2	2
7.5 mg	0.75 mL	75 U	1	1
10 mg	1 mL	100 U	1	1
12.5 mg				Not from this vial: more than the vial holds
15 mg				Not from this vial: more than the vial holds

Vial15 mg

Add water1 mL

Strength15 mg/mL

1 unit150 mcg

Dose	Draw	Units	Doses in vial	Used within 28 days
2.5 mg	0.167 mL	16.7 U	6	4 (2 left over: choose a smaller vial)
5 mg	0.333 mL	33.3 U	3	3
7.5 mg	0.5 mL	50 U	2	2
10 mg	0.667 mL	66.7 U	1	1
12.5 mg	0.833 mL	83.3 U	1	1
15 mg	1 mL	100 U	1	1

Vial20 mg

Add water1 mL

Strength20 mg/mL

1 unit200 mcg

Dose	Draw	Units	Doses in vial	Used within 28 days
2.5 mg	0.125 mL	12.5 U	8	4 (4 left over: choose a smaller vial)
5 mg	0.25 mL	25 U	4	4
7.5 mg	0.375 mL	37.5 U	2	2
10 mg	0.5 mL	50 U	2	2
12.5 mg	0.625 mL	62.5 U	1	1
15 mg	0.75 mL	75 U	1	1

Vial30 mg

Add water1.5 mL

Strength20 mg/mL

1 unit200 mcg

Dose	Draw	Units	Doses in vial	Used within 28 days
2.5 mg	0.125 mL	12.5 U	12	4 (8 left over: choose a smaller vial)
5 mg	0.25 mL	25 U	6	4 (2 left over: choose a smaller vial)
7.5 mg	0.375 mL	37.5 U	4	4
10 mg	0.5 mL	50 U	3	3
12.5 mg	0.625 mL	62.5 U	2	2
15 mg	0.75 mL	75 U	2	2

Vial40 mg

Add water2 mL

Strength20 mg/mL

1 unit200 mcg

Dose	Draw	Units	Doses in vial	Used within 28 days
2.5 mg	0.125 mL	12.5 U	16	4 (12 left over: choose a smaller vial)
5 mg	0.25 mL	25 U	8	4 (4 left over: choose a smaller vial)
7.5 mg	0.375 mL	37.5 U	5	4 (1 left over: choose a smaller vial)
10 mg	0.5 mL	50 U	4	4
12.5 mg	0.625 mL	62.5 U	3	3
15 mg	0.75 mL	75 U	2	2

Vial50 mg

Add water2 mL

Strength25 mg/mL

1 unit250 mcg

Dose	Draw	Units	Doses in vial	Used within 28 days
2.5 mg	0.1 mL	10 U	20	4 (16 left over: choose a smaller vial)
5 mg	0.2 mL	20 U	10	4 (6 left over: choose a smaller vial)
7.5 mg	0.3 mL	30 U	6	4 (2 left over: choose a smaller vial)
10 mg	0.4 mL	40 U	5	4 (1 left over: choose a smaller vial)
12.5 mg	0.5 mL	50 U	4	4
15 mg	0.6 mL	60 U	3	3

Vial60 mg

Add water3 mL

Strength20 mg/mL

1 unit200 mcg

Dose	Draw	Units	Doses in vial	Used within 28 days
2.5 mg	0.125 mL	12.5 U	24	4 (20 left over: choose a smaller vial)
5 mg	0.25 mL	25 U	12	4 (8 left over: choose a smaller vial)
7.5 mg	0.375 mL	37.5 U	8	4 (4 left over: choose a smaller vial)
10 mg	0.5 mL	50 U	6	4 (2 left over: choose a smaller vial)
12.5 mg	0.625 mL	62.5 U	4	4
15 mg	0.75 mL	75 U	4	4

Certificates, tools and where to buy

Certificates on file for Tirzepatide: the laboratory's original pages.

Work out the draw · Plan a schedule · Reading a syringe · Shop

Do not use if

Personal or family history of medullary thyroid carcinoma, or MEN 2
Known serious allergy to tirzepatide

Watch for

Nausea, diarrhoea, vomiting and constipation, mostly after a dose increase
Gallbladder problems (gallstones), especially with fast weight loss
Dehydration from stomach side effects, which can strain the kidneys
Low blood sugar when used with insulin or a sulfonylurea

Stop and get medical help if

Severe stomach pain that may go through to the back (possible pancreatitis)
Pain under the right ribs, fever, yellow eyes or skin (possible gallbladder problem)
Signs of a severe allergic reaction
Unable to keep fluids down

Interactions

Oral birth control pills may work less well for 4 weeks after starting and after each dose increase; the label advises a non-oral method or adding a barrier method in those weeks
Do not combine with another GLP-1 medicine (semaglutide, liraglutide)
Insulin or sulfonylureas: the dose of these may need lowering

A good vial

White to off-white dry cake
Clear, colourless solution after mixing

Do not use the vial if

Cloudy or particles after gentle swirling
Yellow or brown colour
Collapsed or melted cake

Combinations

With	Status	Why, and on what basis
Semaglutide	Avoid	Same drug class; adds side effects without evidence of more benefit (label)

Evidence

Large randomised human trials at 5, 10 and 15 mg once a week, in obesity (SURMOUNT) and type 2 diabetes (SURPASS).

NCT04184622 SURMOUNT-1: 2,539 adults with obesity, 72 weeks. Mean weight change at 15 mg about -21% vs about -3% placebo (treatment-regimen estimand).
PMID:35658024 Jastreboff AM et al. Tirzepatide once weekly for the treatment of obesity. N Engl J Med 2022.
PMID:34647404 Furihata et al. 2021: plasma half-life about 5 days.

This page is research and education. It is not medical advice and not a personal dosing plan. Doses marked "Product label" come from the official prescribing information; doses marked "Market practice" show what is used in this market and are not a recommendation. Use prescription medicines only under the care of a licensed physician.