How the Microdose Tirzepatide Protocol Works: 1 to 2 mg Total per Week

Last updated: September 17, 2026

Written by: Jay Hastings, CEO of PlexusDx, and Jayden Lee, PharmD, EMBA, PlexusDx Medical Director

Jay Hastings is the CEO of PlexusDx, a precision health company focused on genetic testing, blood biomarker insights, and personalized wellness recommendations. He has more than 20 years of experience across healthcare innovation, genomics, laboratory operations, healthcare investing, and strategic finance.

Medically reviewed by: Jayden Lee, PharmD, EMBA

Jayden Lee, PharmD, EMBA, is the PlexusDx Medical Director, with a PharmD and MBA specializing in pharmacogenomics and clinical product development, with a proven ability to bridge the gap between genomic research and practical patient outcomes. Dr. Lee has more than 10 years of professional experience in clinical pharmacy, academia, and research.

This article is part of the PlexusDx Education Hub — your resource for evidence-based guidance on Peptides & GLP-1. Browse all Peptides & GLP-1 education

People search “how to microdose tirzepatide” hoping for a chart. We are not going to give you one, because a dose is a prescription decision. What we can do is describe, plainly, how the program in the PlexusDx study was set up. Microdosing is not a medical term. In the PlexusDx study it meant a total weekly dose of 1 or 2 mg of injectable tirzepatide, below the usual 2.5 mg starting dose.

The medication

Every patient in the study received compounded injectable tirzepatide with vitamin B12 at a total weekly dose of 1 to 2 mg. It was prepared by state-licensed compounding pharmacies operating in FDA-registered facilities. It is the same molecule as in the FDA-approved products, at an amount below their 2.5 mg starting dose. It is not an FDA-approved product, and it did not include semaglutide or any oral form.

Dose was counted by the weekly total

The study sorted patients by the total amount they received in a week, not by the amount in each shot. That matters because two people can inject on different days and still get the same weekly total.

• 53 of 60 patients (88.3%) started at 1 mg a week in total. All 53 took 1 mg once a week.
• 7 of 60 patients (11.7%) started at 2 mg a week in total. Four of the seven took 1 mg twice a week. Three took 2 mg once a week.

So the study was not limited to once-a-week dosing, and it did not compare once-weekly with twice-weekly schedules. It simply recorded what the prescribers ordered.

Who set the doses

An independent network of U.S.-licensed clinicians, working through a state-licensed telehealth platform, reviewed each patient’s intake, decided whether to prescribe, and chose the starting dose. The same clinicians decided on any change. Some patients later moved up to 2 mg a week. Once a patient moved above 2 mg a week, their later weights were no longer counted as low-dose exposure in the study.

How patients were followed

Patients reported their weight and how they felt at routine check-ins. These were care check-ins, not study visits. Weights were self-reported, not measured in a clinic. The study only counted a weight if it came at least 14 days after the first dose, during continuous treatment, and while the weekly total was 2 mg or less. Nothing was filled in or estimated when a number was missing.

What the protocol was not

It was not a fixed schedule that everyone followed. It was not a plan you can copy. It was not a trial protocol with visits on set days. It was the ordinary care of one program, looked at afterward. That is why the study calls itself retrospective and observational, and why it cannot tell anyone what dose to take.

What to ask a prescriber

If you are curious about a low start, bring these questions to a licensed clinician. What weekly total are you suggesting, and why? How will we decide whether it changes? How will we track weight and side effects? What would make you stop or lower it? Those are the decisions a prescriber owns. A blog post, including this one, cannot make them for you.

Related: what is a microdose of tirzepatide, who a microdose start is for, and how we checked the data.

About the PlexusDx study

A retrospective, single-organization observational study of adults documented as new to GLP-1 medicines with BMI ≥27 kg/m²; no comparison group; self-reported weights; not a clinical trial; preprint not yet peer reviewed. The records came from the commercial care program that PlexusDx operates. Care was delivered by an independent network of U.S.-licensed clinicians through a state-licensed telehealth platform. The medication was compounded injectable tirzepatide with vitamin B12 at a total weekly dose of 1 to 2 mg, prepared by state-licensed compounding pharmacies operating in FDA-registered facilities. The study was written by Jay Hastings (PlexusDx CEO) and Jayden Lee, PharmD, EMBA (PlexusDx Medical Director). See the PlexusDx microdose tirzepatide study (60 patients, 2026).

The authors’ conclusion, in their words: “These hypothesis-generating observations support prospective comparative study, not conclusions about causality, equivalent dosing, or long-term safety.” The full preprint is on medRxiv: Weight Loss With Microdose Tirzepatide: Real-World Outcomes in Patients Initiating Treatment Below 2.5 mg Weekly (doi:10.64898/2026.09.15.26363172; posted September 17, 2026; CC BY 4.0). It has not yet been peer reviewed.

Where PlexusDx fits

PlexusDx offers compounded tirzepatide through its Weight Management Protocols, including the entry-tier Microdose GLP-1 Protocol. You fill out a short intake. A licensed clinician reviews it and decides what, if anything, fits you. The study described here looked back at records. It is not a promise of any result.

This article is educational. PlexusDx offers compounded tirzepatide through its Weight Management Protocols. The GLP-1 & Peptide Pathways Genetic Test analyzes how your genes influence peptide-related biological pathways. It does not recommend, prescribe, or determine which peptides you should use. Consult a qualified healthcare provider before beginning any peptide protocol. Compounded tirzepatide is not an FDA-approved drug product. It is prepared by state-licensed compounding pharmacies under federal compounding rules and is not the same as Zepbound® or Mounjaro®. Zepbound® and Mounjaro® are registered trademarks of Eli Lilly and Company. PlexusDx is not affiliated with or endorsed by Eli Lilly and Company.

Frequently Asked Questions

How do you microdose tirzepatide?

You do not set the dose yourself. A licensed prescriber decides whether to prescribe a lower-than-label dose and what it should be. In the PlexusDx study, clinicians ordered a total of 1 or 2 mg a week, and 53 of 60 patients started at 1 mg once weekly.

Was the microdose tirzepatide protocol once a week?

Mostly, but not only. All 53 patients who started at 1 mg a week took it once weekly. Of the 7 who started at 2 mg a week, four took 1 mg twice weekly and three took 2 mg once weekly. The study did not compare the two schedules.

Is there a microdose tirzepatide chart or schedule I can follow?

No. The PlexusDx study did not use a fixed schedule, and this article does not give one. Dosing is a prescription decision made by a licensed clinician based on your history and how you respond. Any chart found online is not a substitute for that decision.

What happened when a patient went above 2 mg a week?

Their later weights were no longer counted as low-dose exposure in the study. The analysis only included weights taken while the weekly total was 2 mg or less, at least 14 days after the first dose, during continuous treatment. Care continued; the study window for that patient closed.

What was in the microdose tirzepatide medication?

Compounded injectable tirzepatide with vitamin B12, at a total weekly dose of 1 to 2 mg, prepared by state-licensed compounding pharmacies operating in FDA-registered facilities. It did not include semaglutide or any oral form. Compounded medication is not an FDA-approved drug product.

This article is part of the PlexusDx Education Hub. Browse all Peptides & GLP-1 education

Medical and Editorial Standards

Medical review process: This article was reviewed for medical accuracy, scientific clarity, evidence alignment, and appropriate discussion of genetics, medications, supplements, biomarkers, and health-related claims.

Sources and evidence: PlexusDx educational content is developed using peer-reviewed research, clinical literature, reputable medical references, and, where applicable, public health or regulatory guidance.

Commercial transparency: PlexusDx offers genetic testing, blood biomarker testing, personalized supplement recommendations, and related precision wellness services. Product mentions are intended to help readers understand available options and should not be interpreted as medical advice.

Important disclaimer: PlexusDx educational content is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about medications, supplements, genetic testing, lab testing, or health-related care.