This tirzepatide dosage chart and reference guide covers the weekly dosing steps reported in trial literature and prescribing summaries. It also explains how the compound works, what trials reported on weight, side effects, and stopping, and how it compares with retatrutide. The sections focus on the questions researchers ask most often.
What Is Tirzepatide?
Tirzepatide is a once-weekly injectable peptide that activates two receptors, GIP and GLP-1, which is why it is described as a dual agonist. The US approved it for type 2 diabetes in May 2022 and for chronic weight management in November 2023. A sleep apnea indication in adults with obesity followed in December 2024.
How Does Tirzepatide Work?
Both receptors belong to the gut hormone system that coordinates appetite, digestion, and blood sugar. Activating them raises insulin release when glucose is high, lowers glucagon, slows gastric emptying, and increases satiety. Reference summaries note that tirzepatide binds GIP receptors with greater affinity than GLP-1 receptors.
The half-life is about 5 days, which fits the once-weekly schedule and explains why drug reference pages describe a minimum of 3 days between injections.
See also: Tirzepatide Mechanism
How Much Weight Can You Lose on Tirzepatide?
SURMOUNT-1, published in the New England Journal of Medicine in 2022, followed adults with obesity for 72 weeks. Mean weight change was 15.0% at 5 mg, 19.5% at 10 mg, and 20.9% at 15 mg, against 3.1% with placebo.
These figures are averages across trial participants, and individual results varied. They also reflect the full escalation schedule shown in the dosing section below, not a single dose given from the start.
Tirzepatide Side Effects
Trial records and drug reference pages list gastrointestinal events most often: nausea, diarrhea, vomiting, constipation, decreased appetite, and abdominal pain. Injection site reactions, dry mouth, fatigue, and hair loss also appear in health authority summaries. Rarer serious events listed by a major academic medical center include pancreatitis, gallbladder problems, kidney problems, and thyroid concerns.
Drug reference pages note that the low starting dose and gradual escalation were designed to reduce gastrointestinal events. These are adverse event signals recorded in trial and reference literature, not guidance for any person.
See also: Tirzepatide Side Effects in the Research Literature
How Is Tirzepatide Used?
Health authority and drug reference pages describe a subcutaneous injection once weekly, on the same day each week, at any time of day with or without food. Injection sites rotate among the abdomen, thigh, and upper arm, and the product is kept refrigerated before use. One reference notes it is not mixed with insulin in the same syringe.
This describes how the prescription product is used under medical supervision. It is not a protocol for research material.
Comparing Tirzepatide to Retatrutide
Retatrutide adds a third target, the glucagon receptor, to the GIP and GLP-1 activity that tirzepatide has. It is still in Phase 3 development, so no label schedule exists yet. For the full side-by-side, see retatrutide vs tirzepatide and the retatrutide explained overview.
Table 1. Tirzepatide and retatrutide compared
| Feature | Tirzepatide | Retatrutide |
|---|---|---|
| Receptors targeted | GIP and GLP-1 | GIP, GLP-1, and glucagon |
| Development stage | Approved, completed Phase 3 programs | Phase 3 (TRIUMPH program) |
| Reported weight change | Up to about 20.9% at 72 weeks | Up to about 28.3% at 80 weeks |
| Trial schedule | Once weekly, 2.5 mg stepping to 15 mg | Once weekly, doses up to 12 mg |
No trial has compared the two head to head, so the figures above come from separate studies and are a research signal, not proof that one outperforms the other.
Tirzepatide Dosing Information
The schedule below follows the escalation described in drug reference and health authority prescribing summaries. It starts at 2.5 mg once weekly and rises in 2.5 mg steps after at least 4 weeks at each level, up to 15 mg.
Table 2. Tirzepatide weekly dosing steps in the label record
| Step | Weekly amount | Earliest timing | Role in the schedule | Reported change at 72 weeks (SURMOUNT-1) |
|---|---|---|---|---|
| 1 | 2.5 mg | Weeks 1 to 4 | Starting step | Not reported separately |
| 2 | 5 mg | Weeks 5 to 8 | Maintenance-eligible step | 15.0% |
| 3 | 7.5 mg | Weeks 9 to 12 | Escalation step | Not reported separately |
| 4 | 10 mg | Weeks 13 to 16 | Maintenance-eligible step | 19.5% |
| 5 | 12.5 mg | Weeks 17 to 20 | Escalation step | Not reported separately |
| 6 | 15 mg | Week 21 onward | Maintenance-eligible step and adult maximum | 20.9% |
Timing is the earliest point each step can begin, since the label allows longer stays at any level. The schedule applies to the prescription product under medical supervision, and a chart like this is a map of one published schedule, not a replacement for the primary trial papers.
Dosing charts list amounts in milligrams, but a lab working from a lyophilized vial also needs concentration in milligrams per milliliter. The calculation is the vial amount divided by the diluent volume added.
Table 3. Concentration for a 10 mg vial at three diluent volumes
| Diluent added | Resulting concentration |
|---|---|
| 1 mL | 10 mg/mL |
| 2 mL | 5 mg/mL |
| 4 mL | 2.5 mg/mL |
Volume for any target amount equals the amount divided by the concentration. The Concentration Calculator runs this arithmetic for any vial size, and the tirzepatide dosage walkthrough covers reconstitution handling step by step. To compare schedules, see the retatrutide dosage guide.
What Happens When a Dose Is Missed?
Drug reference and health authority pages describe a 4 day (96 hour) window. Within that window a missed dose is given as soon as possible. After it, the dose is skipped and the regular day resumes. Doses are not doubled, and at least 3 days separate injections.
What Happens in an Overdose?
Health authority pages note that using more than the prescribed amount can sometimes be dangerous, and they direct readers to a health service or poison control center. Drug reference pages describe emergency services for serious symptoms such as seizures, loss of consciousness, or breathing difficulty.
How Long Does It Take to Lose Weight on Tirzepatide?
SURMOUNT-1 reported its results at 72 weeks, after an escalation period of at least 20 weeks to reach 15 mg. Weight change builds gradually across that period, and the figures are endpoints rather than a weekly rate. Drug reference pages do not give a fixed timeline, and individual responses varied in the trials.
Do You Regain Weight After Stopping Tirzepatide?
SURMOUNT-4, published in JAMA in 2024, gave all participants tirzepatide for a 36-week lead-in period, during which mean weight fell by about 20.9%. Participants were then randomized to continue tirzepatide or switch to placebo for 52 weeks. The continued group lost a further 5.5%, while the placebo group regained 14.0%. Reference summaries describe the broader pattern as regaining more than half of lost weight within a year, with a return toward baseline over roughly 18 months.
Research Use Disclaimer
This content is provided for Research Use Only (RUO). The compounds discussed are not drugs, dietary supplements, foods, or cosmetics, and are not intended for human or animal consumption, diagnostic use, or therapeutic use of any kind. They have not been evaluated by the FDA for safety or efficacy in humans. Any research use must be conducted by qualified professionals in a controlled laboratory environment, in accordance with all applicable institutional, local, and federal regulations.
Sources
- Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). N Engl J Med. 2022.
- Aronne LJ, et al. Continued treatment with tirzepatide for maintenance of weight reduction in adults with obesity (SURMOUNT-4). JAMA. 2024.
- Mayo Clinic. Tirzepatide (subcutaneous route), description and proper use. mayoclinic.org.
- NHS. Tirzepatide. nhs.uk/medicines/tirzepatide.
- Cleveland Clinic. Tirzepatide injection. my.clevelandclinic.org.
- Drugs.com. Tirzepatide: uses, dosage, side effects. drugs.com/tirzepatide.html.
- Wikipedia. Tirzepatide. en.wikipedia.org/wiki/Tirzepatide.
Explore the weight loss research category for related compounds, or read the tirzepatide dosage guide for reconstitution handling.
