Tirzepatide (commercial brands Mounjaro and Zepbound) is injected subcutaneously once a week on a gradual dose-escalation principle. The standard Mounjaro schedule starts at 2.5 mg for the first 4 weeks, after which the dose is raised to 5 mg, and then in steps of 2.5 mg at intervals of at least 4 weeks up to a maintenance level of 10, 12.5 or 15 mg. Below we organize the documented Mounjaro dosing guide on titration, frequency and storage in a research format, with no self-medication advice.
This article describes tirzepatide dosage as it is recorded in the registration protocols and peer-reviewed clinical studies. We give no instructions on "how to treat yourself" and do not replace a physician's consultation: the decision to use an approved drug is made only by a qualified medical professional.
In brief: the tirzepatide titration schedule
Tirzepatide is a dual agonist of the GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) receptors. The key feature of its use is a mandatory dose-escalation phase, during which the body adapts to the drug and the frequency of gastrointestinal reactions decreases.
| Step | Dose (once a week, subcutaneously) | Minimum time on the dose | Role of the dose |
|---|---|---|---|
| Start | 2.5 mg | 4 weeks | Initiation, not therapeutic, "priming" of the GI tract |
| Step 1 | 5 mg | 4 weeks or more | Lowest maintenance |
| Step 2 | 7.5 mg | 4 weeks or more | Intermediate titration |
| Step 3 | 10 mg | 4 weeks or more | Maintenance |
| Step 4 | 12.5 mg | 4 weeks or more | Intermediate titration |
| Step 5 | 15 mg | , | Maximum maintenance |
The key numbers of the documented schedule:
- Start, 2.5 mg once a week for 4 weeks. This is an initiation dose, not a therapeutic one: its purpose is to reduce nausea at the start.
- Next, 5 mg, and each subsequent increase happens in a step of 2.5 mg no sooner than 4 weeks on the current dose.
- Maintenance doses, 5, 10 and 15 mg; the intermediate 7.5 and 12.5 mg are used only as titration steps.
- Maximum dose, 15 mg once a week.
How titration works and why the start is 2.5 mg
The logic of gradual escalation explains why how to use Mounjaro does not come down to "take the target dose and inject it". The starting 2.5 mg is pharmacologically not designed for the full effect, it serves as an adaptation window for the gastrointestinal tract. In the clinical protocols most episodes of nausea, vomiting and diarrhea fell precisely on the escalation period and weakened over time.
That is why tirzepatide dosage provides for at least 4 weeks on each step before an increase. Speeding up titration gives no added benefit, but instead raises the risk of tolerability reactions. If tolerability is poor at a given step, clinical practice considers delaying the increase or returning to the previous dose, but that is a physician's decision, not a matter for independent experimentation.
Route and frequency of injection
The documented Mounjaro guide on injection technique:
- Route, subcutaneous. Typical areas are the abdomen, thigh or the outer surface of the upper arm. Rotating injection sites is recommended.
- Frequency, once a week, on the same day of the week. The time of day does not matter, injection is possible regardless of meals.
- Day flexibility: if needed, the day of the weekly injection can be changed, as long as an interval of at least 72 hours (3 days) is kept between two injections.
- Each dose is injected with a new needle/device; the drug is inspected before injection and must be clear and free of particles.
Once a week is a consequence of the pharmacokinetics: tirzepatide has a long half-life (about 5 days), which makes a weekly regimen sufficient for a stable concentration.
Storage
Storage conditions of approved tirzepatide (per the manufacturer):
- Primary mode, refrigerator 2–8 °C. Store until the expiry date.
- Outside the refrigerator the drug can be kept at a temperature of up to 30 °C for no longer than 21 days; after that unused drug is discarded.
- Do not freeze. Frozen drug must not be used and should be inspected before each injection.
- Protect from direct light; store in the original packaging.
These parameters apply to the finished medicine. For research substances the storage conditions are defined by the certificate of analysis of the specific batch, see the research-grade section below.
What the clinical protocols showed
The titration schedule above is not an abstraction but the protocol under which the key registration studies were run.
- SURPASS-2 (Frías et al., NEJM, 2021), a study of tirzepatide versus semaglutide 1 mg in adults with type 2 diabetes. Tirzepatide was used at maintenance doses of 5, 10 and 15 mg on the same step schedule.
- SURMOUNT-1 (Jastreboff et al., NEJM, 2022), a study of 2,539 adults with obesity or overweight without diabetes. Participants received tirzepatide 5, 10 or 15 mg once a week for 72 weeks, of which the first 20 weeks were the dose-escalation phase. The documented mean change in body weight was about -15% for the 5 mg dose and up to -20.9% for the 15 mg dose versus -3.1% in the placebo group.
These figures are documented results of clinical groups under controlled conditions, not a promise of an individual result. The individual response varies, and outside the study it is not predictable.
Safety, limitations and cautions
This article is deliberately limited to the topic of the regimen of use and dosing. Questions of tolerability, gastrointestinal reactions and contraindications we cover separately, so as not to duplicate the material:
- More on tolerability and adverse reactions in our separate overview of tirzepatide side effects (see the blog).
- A summary of documented clinical observations and the context of use in the reviews section (see the blog).
A few key limitations:
- The schedule above is a general documented protocol, not a personal prescription. The actual starting dose, pace of titration and target level are set by a physician, taking indications and accompanying conditions into account.
- Tirzepatide is a prescription drug with approved indications; use outside them is not described by this article.
- The material is not medical advice and does not encourage independent dose selection.
Research-grade context and substance purity
When it comes to tirzepatide as a research substance (rather than a finished branded drug), what comes to the fore is not a "treatment schedule" but the analytical quality of the material: confirmed identity, purity and the absence of impurities. For laboratory work it is the certificate of analysis (COA) that defines exactly what the researcher is working with, and how to store that substance correctly.
Our tirzepatide product page gives the parameters of the research-grade material with a focus on purity and batch documentation, a basic requirement for the reproducibility of any study. A broader professional context, the dual GIP/GLP-1 mechanism of action, pharmacokinetics and a review of the evidence base, is collected in our tirzepatide monograph.
The distinction here is fundamental: the Mounjaro schedule above describes the use of an approved medicine under a physician's supervision, whereas a research-grade substance is intended solely for laboratory research and is not a drug for administration to humans.
