# Tirzepatide — dosage, half-life & reference guide | PepVault

Source: https://pepvault.app/peptides/tirzepatide

Last updated: 2026-09-26

[Library](https://pepvault.app/peptides) [Metabolic & GLP-1](https://pepvault.app/peptides#metabolic) reviewed September 2026

# Tirzepatide Dosage, half-life & reference guide

Also known as Mounjaro · Zepbound · LY3298176

The first dual GIP/GLP-1 receptor agonist: it activates two gut-hormone pathways at once, and in a head-to-head trial it produced more weight loss than semaglutide (20.2% vs 13.7% at 72 weeks).

- **FDA label:** 2.5–15 mg starting dose 2.5 mg
- **How often:** Weekly
- **Half-life:** ~5 days
- **Evidence:** Established
- **Route:** SubQ injection

[Tirzepatide dose guide](https://pepvault.app/lab/dosage/tirzepatide)

## How it works.

Dual GIP/GLP-1 receptor agonist. Significantly reduces body weight through appetite suppression, slowed gastric emptying, and improved insulin sensitivity. Approved for T2DM and obesity management.

**Commonly reported:** Very strong appetite suppression and meals ending early, with nausea or tiredness for a day or two after the injection, mostly after dose increases. FDA-approved for diabetes (Mounjaro) and for weight management and sleep apnea (Zepbound).

### Half-life & active level

The half-life of Tirzepatide is ~5 days (FDA label).

Here's how a typical Tirzepatide schedule accumulates over four weeks (one-compartment estimate).

An estimate from the half-life above, not a measurement. See your own curve build live in [the half-life calculator](https://pepvault.app/tools/peptide-half-life-calculator).

## Where Tirzepatide works.

- ### Appetite & metabolism

  **In people.** In a head-to-head trial it produced more weight loss than semaglutide (20.2% vs 13.7% at 72 weeks).

An area lights for what a peptide is used for and what people report, with the evidence beside it. It isn’t a promise that it works there.

## Week by week.

What to expect in the first 8 weeks

- **Onset:** Days–2 weeks
- **Peak effect:** 72+ weeks
- **Duration:** Ongoing

1. Day 1–28 · 2.5 mg RCT

   ### Getting your gut acclimated

   The 2.5mg run-in lets your gut adapt to GIP/GLP-1 signaling. Expect appetite to drop within days and some mild nausea in week 1–2. Don't expect weight loss yet — you're building tolerance for the real dose.

   The science

   The 2.5mg run-in is per FDA Zepbound labeling, there to limit GI side effects at higher doses. The GIP component eases nausea in animal studies; in the SURMOUNT-5 head-to-head, nausea rates matched semaglutide (44% each), but fewer people stopped for GI side effects over 72 weeks (2.7% vs 5.6%).

   Sources

   - FDA Zepbound label (2024)
   - Aronne et al. (2025)

   Updated Sep 2026
2. Day 29–56 · 5 mg RCT

   ### First therapeutic dose — weight drops

   You're at 5mg — the first real therapeutic dose. Appetite suppression is fully online and you should start seeing clear scale movement. SURMOUNT-1's 5mg arm reached 15% at 72 weeks.

   The science

   Jastreboff 2022 (NEJM SURMOUNT-1) documented the 5mg arm reaching −15% body weight at week 72. "Food noise" reduction is commonly reported in this window — users describe not thinking about food between meals for the first time in years.

   Sources

   - Jastreboff et al. (2022)

   Updated Apr 2026
3. Any day RCT

   ### What Tirzepatide is built on

   One of the most thoroughly trialed weight-loss drugs in history: SURMOUNT 1 through 5, a head-to-head win over semaglutide, and an FDA approval for obstructive sleep apnea added Dec 2024.

   The science

   Eli Lilly (Mounjaro for diabetes 2022; Zepbound for obesity 2023). SURMOUNT-OSA (Malhotra 2024 NEJM) expanded the FDA label for moderate-to-severe obstructive sleep apnea with obesity. SUMMIT 2024 showed tirzepatide reduces HFpEF worsening events — opening cardiovascular-outcome use cases beyond weight management.

   Sources

   - Jastreboff et al. (2022)
   - Aronne et al. (2025)

   Updated Apr 2026
4. With BPC-157 Community

   ### Why people add BPC-157 to Tirz

   GI side effects during Tirz titration can be rough, and BPC-157, first studied as a stomach-protecting peptide, is added to ease them. Commonly reported: smoother step-ups, especially the later ones.

   The science

   Mechanism fit: BPC-157 is a fragment of a "body protection compound" first isolated from human gastric juice and characterized as gastroprotective in animal studies (gut mucosal integrity, reduced NSAID damage, gut-brain axis modulation). Tirz nausea isn't caused by gastric damage, and no trial has tested the combination; the pattern comes from community reports.

   Sources

   - Sikiric et al. (2018)

   Updated Sep 2026
5. Any day Clinical

   ### Protein + lifting decide what the loss is made of

   Tirz may spare a bit more lean mass than GLP-1-only drugs, though that hasn't been tested head to head, and a meaningful share of any rapid loss is muscle. Keep protein around 1.6–2.2g/kg and keep training resistance through the cut. The appetite suppression handles intake; your protein and lifting decide whether the scale drop is fat or muscle.

   The science

   Across incretin body-composition data, roughly 25–40% of weight lost is lean mass; in SURMOUNT-1 about three-quarters of the loss was fat, the same share as placebo, and no trial has compared lean-mass sparing against pure GLP-1s head to head. Muscle-sparing add-on trials (apitegromab + tirzepatide, EMBRAZE: ~1.9kg less lean loss; bimagrumab + sema: ~92% of loss from fat) show the field moving, but none is standard care — protein and resistance training remain the available levers.

   Sources

   - EMBRAZE (2025)

   Updated Sep 2026

### After week 8

1. Day 57–112 · 7.5 mg RCT

   ### Dual agonism in full effect

   Dual agonism is in full effect. Commonly reported: weight loss picking up pace and body composition shifting in a way people notice.

   The science

   SURMOUNT-1 participants in the 10mg arm reached approximately −19% at 72wk (Jastreboff 2022). Whether the GIP arm spares lean mass hasn't been tested head to head; SURMOUNT-5 compared weight and waist with semaglutide, not body composition.

   Sources

   - Jastreboff et al. (2022)
   - Aronne et al. (2025)

   Updated Sep 2026
2. Day 113–168 · 12.5 mg RCT

   ### Max titration reached

   Max titration (12.5 → 15mg). Appetite suppression is strongest here, and 'food noise silence' is the most common subjective change. If nausea's rough, holding at 12.5 is a reasonable call.

   The science

   Zepbound prescribing info 2024 documents the GI discontinuation rate rising from 3.3% at 10mg to 4.3% at 15mg. SURMOUNT-1 15mg arm reached −22.5% at 72wk. Some users plateau at 10mg and never need to escalate — staying at the lowest effective dose is the community norm.

   Sources

   - FDA Zepbound label (2024)
   - Jastreboff et al. (2022)

   Updated Apr 2026
3. Day 169–504 RCT

   ### Weeks 24 to 72: where most people plateau

   Most people reach a weight plateau between about 6 and 9 months, and nearly 9 in 10 have plateaued by week 72; that is expected, not a sign it stopped working. In the SURMOUNT-5 head-to-head, tirzepatide reached 20.2% loss at 72 weeks against 13.7% for semaglutide, with nearly twice as many people crossing 25% loss.

   The science

   Aronne 2025 (NEJM SURMOUNT-5, 751 patients, 72wk): the first direct Tirz-vs-Sema comparison. Tirz arm hit 20.2% vs 13.7% for sema — ~47% greater relative loss — and ≥25% loss was reached by 31.6% on tirz vs 16.1% on sema. Stopping because of GI side effects: 2.7% vs 5.6%. A post-hoc analysis of SURMOUNT-1 found a median time to plateau of 24–36 weeks, with about 88–90% plateaued by week 72 (Horn 2025). SURMOUNT-OSA also showed ~25 AHI event reduction — which led to the Dec 2024 FDA approval for obstructive sleep apnea with obesity.

   Sources

   - Aronne et al. (2025)
   - Horn et al. (2025)
   - Malhotra et al. (2024)

   Updated Sep 2026
4. Day 365+ RCT

   ### A maintenance medication, not a course

   Before deciding to stop, know the pattern: stopping tirzepatide usually means regaining most of the loss. A 2026 BMJ meta-analysis puts it around 10kg back in the first year and back to baseline in about 18 months, and in SURMOUNT-4 people switched to placebo regained 14% of their body weight within a year. Hold, slow-taper, or stop is a call for you and your clinician — go in expecting a long-term relationship, not a fixed course.

   The science

   SURMOUNT-4 (withdrawal design) and a BMJ meta-analysis (West 2026) document substantial regain after discontinuation (~9.9kg in year 1, back to baseline by ~1.5 years), reflecting that incretin therapy maintains a metabolic set point rather than resetting it. The continue/taper/stop decision is yours, made with your clinician.

   Sources

   - SURMOUNT-4 (2024)
   - West et al. (2026)

   Updated Sep 2026

Day 1 is the day you start it.

SURMOUNT Phase III trials. FDA-approved. Head-to-head with semaglutide showing superior weight loss.

Clinical trial data

## Mixing and a typical run.

Example numbers

### Reconstitution example

Reconstitute a 10 mg vial of Tirzepatide with 2 mL of bacteriostatic water and a 2.5 mg dose is 50 units on a U-100 syringe, about 4 doses per vial.

- **Vial:** 10 mg
- **Water:** 2 mL
- **Amount:** 2.5 mg

Draw to **50 units**

0.5 mL insulin syringe · 50 units

[Mix it in the Reconstitution Lab](https://pepvault.app/lab) [Open the calculator](https://pepvault.app/tools/reconstitution-calculator)

### Run notes

- **Cycle:** FDA-approved for ongoing use. Titrate slowly upward. Community maintains on minimum effective dose. Community practice — opinions vary. Not a clinical recommendation.
- **Timing:** Once weekly SubQ. Consistent day and time preferred. Can take with or without food.
- **Route:** SubQ injection
- **Stacks:** BPC-157 (GI support), MOTS-c

## Safety.

### Common side effects

- Nausea
- Diarrhea
- Vomiting
- Constipation
- Abdominal pain
- Decreased appetite
- Fatigue

#### Interactions

Tirzepatide delays gastric emptying and can reduce the absorption of concomitant oral medications — the label specifically flags reduced oral-contraceptive efficacy, a documented interaction to discuss with a clinician. Co-use with insulin or insulin secretagogues (sulfonylureas) increases hypoglycemia risk per the label, warranting clinician-guided dose review and glucose monitoring. No specific documented interaction with SSRIs, anticoagulants, or thyroid replacement beyond general caution; raise all medications with your clinician.

### Safety notes

Across the SURMOUNT program and the FDA Zepbound label, the dominant adverse events are gastrointestinal (nausea, diarrhea, vomiting, constipation), mostly mild-moderate and escalation-related. The label carries a boxed warning for thyroid C-cell tumors based on rodent studies (human relevance undetermined; contraindicated with personal/family history of medullary thyroid carcinoma or MEN 2). Trial-adjudicated acute pancreatitis was ~0.2% (similar to placebo); gallstones were ~1.1% vs 1.0% on placebo and gallbladder inflammation 0.7% vs 0.2%, partly attributable to rapid weight loss. These are trial/label findings to review with your clinician.

## Goes with.

- [BPC-157 GI support](https://pepvault.app/peptides/bpc-157)
- [MOTS-c](https://pepvault.app/peptides/mots-c)

- ### In the Shred Stack

  Metabolic acceleration & fat loss support

  With [AOD-9604](https://pepvault.app/peptides/aod-9604) and [BPC-157](https://pepvault.app/peptides/bpc-157)

## Compared with.

- [Retatrutide vs Tirzepatide](https://pepvault.app/peptides/compare/retatrutide-vs-tirzepatide)
- [Semaglutide vs Tirzepatide](https://pepvault.app/peptides/compare/semaglutide-vs-tirzepatide)
- [Mazdutide vs Tirzepatide](https://pepvault.app/peptides/compare/mazdutide-vs-tirzepatide)

## Questions people ask.

### What is Tirzepatide?

The first dual GIP/GLP-1 receptor agonist: it activates two gut-hormone pathways at once, and in a head-to-head trial it produced more weight loss than semaglutide (20.2% vs 13.7% at 72 weeks).

### How is Tirzepatide dosed in research?

The FDA label range for Tirzepatide is 2.5–15 mg, weekly, with a 2.5 mg starting dose.

### How long does Tirzepatide last?

The half-life of Tirzepatide is ~5 days (FDA label).

### What do people report on Tirzepatide?

Commonly reported on Tirzepatide: very strong appetite suppression and meals ending early, with nausea or tiredness for a day or two after the injection, mostly after dose increases. FDA-approved for diabetes (Mounjaro) and for weight management and sleep apnea (Zepbound).

### Is Tirzepatide safe?

The research basis for Tirzepatide is established: clinical trials or FDA-approved use exists. Common side effects in the library: nausea, diarrhea, vomiting, constipation, abdominal pain, decreased appetite and fatigue.

### What does Tirzepatide stack with?

Common stacks for Tirzepatide: BPC-157 (GI support) and MOTS-c. Curated stacks with Tirzepatide: Shred Stack.

## Research.

The literature

### Search the latest research

[PubMed](https://pubmed.ncbi.nlm.nih.gov/?term=Tirzepatide) [Google Scholar](https://scholar.google.com/scholar?q=Tirzepatide)

Guide

### [How to reconstitute tirzepatide](https://pepvault.app/guides/how-to-reconstitute-tirzepatide)

Read the guide

Guide

### [Retatrutide week by week](https://pepvault.app/guides/retatrutide-week-by-week)

Read the guide

Guide

### [What to take alongside each peptide](https://pepvault.app/guides/what-to-take-with-peptides)

Read the guide

## Reference.

- **Cadence:** Weekly
- **Half-life:** ~5 days ~5 days (FDA label)
- **Research basis:** Established Clinical trials or FDA-approved use exists

## More metabolic & glp-1 peptides

- [Retatrutide 1–12 mg](https://pepvault.app/peptides/retatrutide)
- [Liraglutide 0.6–3 mg](https://pepvault.app/peptides/liraglutide)
- [Dulaglutide 0.75–4.5 mg](https://pepvault.app/peptides/dulaglutide)
- [Orforglipron 0.8–17.2 mg](https://pepvault.app/peptides/orforglipron)
- [Survodutide 0.3–6 mg](https://pepvault.app/peptides/survodutide)
- [Mazdutide 2–6 mg](https://pepvault.app/peptides/mazdutide)

## Free tools

- [Tirzepatide dose guide](https://pepvault.app/lab/dosage/tirzepatide)
- [Reconstitution Lab (3D)](https://pepvault.app/lab)
- [Injection guide (3D)](https://pepvault.app/lab/injection)
- [Peptide Sky (3D)](https://pepvault.app/lab/sky)
- [Peptide tier list](https://pepvault.app/lab/tiers)
- [Reconstitution calculator](https://pepvault.app/tools/reconstitution-calculator)
- [Half-life & active level](https://pepvault.app/tools/peptide-half-life-calculator)
- [GLP-1 titration planner](https://pepvault.app/tools/glp1-titration-calculator)

Track your progress

## Watch it *work.*

Weight, waist and photos in one arc.

[Download on the App Store](https://apps.apple.com/app/apple-store/id6779318649?ppid=616838ec-3248-400f-bd58-4b93f85f1a20&pt=129020030&ct=peptides-progress-band&mt=8)

**34.8 lbs** down since June

Model. Individual results vary.

PepVault for iPhone

## Track Tirzepatide in PepVault

Log every dose, keep your vial and the doses left in it and watch its estimated active level. 7 days free on the yearly plan for new subscribers.

[Download on the App Store](https://apps.apple.com/app/apple-store/id6779318649?ppid=616838ec-3248-400f-bd58-4b93f85f1a20&pt=129020030&ct=peptides-cta&mt=8)

[Open the calculator](https://pepvault.app/tools/reconstitution-calculator) [How the vial count works](https://pepvault.app/peptide-vial-tracker-app) [Explore the live demo](https://pepvault.app/login)

Reviewed September 2026 [How we check the library](https://pepvault.app/about#library)

PepVault is a research and tracking resource, not medical advice. Ranges are what studies used, never a dose for you. Brand names are trademarks of their owners; PepVault is independent of them.

PepVault is a private research and tracking tool, not medical advice. The information here is reference material from published literature and community use — always verify it and discuss any protocol with a qualified clinician before changing it. Ozempic, Wegovy, Rybelsus, Mounjaro, Zepbound, Saxenda, Victoza and Trulicity are trademarks of their respective owners; PepVault is independent and not affiliated with or endorsed by any manufacturer.

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