No protocol hereThis page reports what has been published. It does not describe how to take smaller doses, and it does not recommend them. The Zepbound label says “the 2.5 mg dosage is for treatment initiation and is not approved as a maintenance dosage.”[12] Any change to a dose is a prescriber's decision.
What does microdosing tirzepatide mean?
Microdosing tirzepatide is taking doses below the lowest approved (starting) dose of 2.5 mg, often by drawing partial doses from multi-dose pens. A 2026 review defines it that way, separates it from “split dosing” (smaller doses given more often than weekly), and calls the supporting evidence “mostly anecdotal.”[1] The same review notes the practice is not supported by manufacturers, scientific societies, regulators or guidelines, and calls for proper studies.[1]
Is there a trial of microdosing tirzepatide?
No randomized trial of tirzepatide microdosing or spaced dosing had been published by November 2026; what exists is reviews, letters, observational data and a model.[1]
| Study | Design | What it reported | Limit |
|---|---|---|---|
| Infante 2026[1] | Review | Evidence for microdosing is “mostly anecdotal” | No new data |
| Murugadoss 2026[5] | Health-record study, 1,016 people on repeated 2.5 mg prescriptions | −5.5% average weight change at 12 months | Observational; not proof of intentional low dosing |
| Amioka 2026[6] | Non-randomized cohort, 112 Japanese adults | 2.5 mg: −15.3%; 5 mg: −16.1% at 6 months | Not randomized; 2.5 mg is the label start dose, not a microdose |
| Cengiz 2025[7] | Mathematical model, no patients | Every-2-week dosing kept about 75% of weekly weight loss (simulated) | Simulation only |
| NCT07574723[8] | Randomized trial: label vs flexible titration | Recruiting since May 2026 | No results yet |
The lowest tirzepatide doses actually tested
The smallest weekly dose tested in a randomized trial is 1 mg, in a 26-week phase 2 trial of 318 adults with type 2 diabetes.[2]
| Arm | Body weight change | HbA1c change |
|---|---|---|
| Placebo | −0.4 kg | −0.06% |
| Tirzepatide 1 mg | −0.9 kg | −1.06% |
| Tirzepatide 5 mg | −4.8 kg | −1.73% |
| Tirzepatide 10 mg | −8.7 kg | −1.89% |
| Tirzepatide 15 mg | −11.3 kg | −1.94% |
| Dulaglutide 1.5 mg | −2.7 kg | — |
Weight figures are the per-arm results posted on ClinicalTrials.gov; HbA1c figures are from the Lancet paper, whose authors describe a dose-dependent effect.[3][2] At 1 mg, 13.5% of people lost at least 5% of their weight (0% on placebo), and stomach side effects affected 23.1% versus 9.8%.[3][2] In a 4-week phase 1 study in healthy volunteers, 1.5 mg weekly lowered weight by 1.75 kg versus placebo.[4]
- −0.9 kg1 mg weekly, 26 weeks
- −11.3 kg15 mg weekly, 26 weeks
- −0.4 kgplacebo
What the label trials show about dose
In the large weight trials, more tirzepatide meant more weight loss, and the lowest maintenance dose tested was 5 mg. SURMOUNT-1 reported −15% on 5 mg, −19.5% on 10 mg and −20.9% on 15 mg at 72 weeks, against −3.1% on placebo.[11]
- Stepping down after a full dose: in SURMOUNT-MAINTAIN, after 60 weeks on 10 or 15 mg, people who stayed on that dose were at −21.9% from baseline at week 112, those reduced to 5 mg at −16.6%, and those switched to placebo at −9.9%.[9] The 5 mg group regained 5.6 kg on average.[10]
- No dose below 5 mg was tested in SURMOUNT-MAINTAIN, the trial designed to study lower-dose maintenance.[9]
- 2.5 mg is a 4-week starting dose on the Zepbound label, not a maintenance dose.[12]
Results by dose are on tirzepatide for weight loss, and the label steps on the tirzepatide dosage chart.
Why the label and the FDA warn against partial doses
The approved devices are built to deliver whole labeled doses, and the instructions forbid taking partial or leftover amounts. The Zepbound KwikPen instructions say: “Do not count clicks as you select the dose,” “Do not transfer ZEPBOUND from your Pen into a syringe,” and “Do not inject the leftover medicine.”[12]
The FDA has reported dosing errors from patients “measuring and self-administering incorrect doses,” and adverse events with compounded semaglutide or tirzepatide given “in doses beyond what is in the FDA-approved drug label.”[14] How approved doses translate into volumes is on how many units is 2.5 mg of tirzepatide; see also Zepbound KwikPen.
Related
- Tirzepatide side effectsRates by dose in both labels
- Tirzepatide pillsIs there an oral tirzepatide?
- Compounded tirzepatideFDA status
Frequently asked questions
What is microdosing tirzepatide?
Taking doses smaller than the 2.5 mg starting dose, outside the FDA label. A 2026 review calls the supporting evidence “mostly anecdotal.”[1]
Does microdosing tirzepatide work?
It has not been tested in a randomized trial. The only trial of a very low dose (1 mg weekly) found −0.9 kg versus −0.4 kg on placebo after 26 weeks, in people with type 2 diabetes.[3]
What is the lowest dose of tirzepatide?
Sources
- Infante M et al. Microdosing, fractional and split dosing of injectable GLP-1-based drugs: balancing potential benefits and risks
- Frias JP et al. Efficacy and safety of LY3298176 (tirzepatide) in type 2 diabetes: a randomised phase 2 trial
- NCT03131687 posted results: phase 2 study of tirzepatide in type 2 diabetes
- Coskun T et al. LY3298176, a novel dual GIP and GLP-1 receptor agonist: from discovery to clinical proof of concept
- Murugadoss K et al. Cardiometabolic benefits and tolerability in patients on sustained low doses of semaglutide or tirzepatide
- Amioka M et al. Low-dose tirzepatide for obesity: 2.5 mg versus 5 mg in non-diabetic Japanese adults
- Cengiz A et al. Alternative dosing regimens of GLP-1 receptor agonists may reduce costs and maintain weight loss efficacy
- NCT07574723: tirzepatide titration to reduce side effects in individuals with obesity
- Horn DB et al. Tirzepatide for maintenance of bodyweight reduction in people with obesity (SURMOUNT-MAINTAIN)
- Lilly's Foundayo and lower-dose Zepbound helped people maintain weight loss after switching from higher doses
- Jastreboff AM et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1)
- Zepbound (tirzepatide) injection: prescribing information, Medication Guide and Instructions for Use
- Mounjaro (tirzepatide) injection: prescribing information and Instructions for Use
- FDA's concerns with unapproved GLP-1 drugs used for weight loss