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TiApproved drug

Tirzepatide

A once-weekly dual agonist (GIP and GLP-1 receptors). Approved in the US as Mounjaro (type 2 diabetes) and Zepbound (weight management). In the Philippines it is mostly sold as a research peptide.

Approved in the US · Mounjaro, ZepboundLabel schedule below
OverviewDosingMixingResearchCommunitySafetyFAQSources

Tirzepatide quick reference

TypeGIP / GLP-1 dual agonist
Studied forWeight, diabetes, sleep apnea, prediabetes
EvidenceLarge phase 3 trials; approved in the US
RouteWeekly subcutaneous injection
Half-lifeAbout 5 days

What is Tirzepatide?

Once-weekly peptide acting on GIP and GLP-1 receptors.

Sold as Mounjaro (diabetes) and Zepbound (weight, sleep apnea).

Beat semaglutide in a head-to-head weight trial.

How Tirzepatide works

GIP receptor

Adds to insulin release and acts on fat tissue.

GLP-1 receptor

Slows stomach emptying and signals fullness.

Weekly exposure

A fatty-acid chain binds albumin; half-life is near 5 days.

What Tirzepatide is studied for

PeopleWeight loss

Lost 20.9% on 15 mg at 72 weeks (SURMOUNT-1).

PeopleVersus semaglutide

20.2% vs 13.7% at 72 weeks (SURMOUNT-5).

PeopleType 2 diabetes

HbA1c fell 2.0–2.3 points, beating semaglutide 1 mg (SURPASS-2).

PeopleSleep apnea

Apnea events fell 25–29 per hour vs 5 on placebo (SURMOUNT-OSA).

PeoplePreventing diabetes

With prediabetes, 1.3% vs 13.3% developed diabetes over 176 weeks.

AnimalsBrown fat

In obese mice it boosted amino-acid burning in brown fat.

Tirzepatide dosing protocol

WeeksWeekly amount on the US label
1–42.5 mg (starting amount, not a treatment dose)
5–85 mg
9–127.5 mg (if stepping up)
13–1610 mg
17–2012.5 mg
21+15 mg (maximum)

Weight-management maintenance on the label: 5, 10 or 15 mg; for sleep apnoea 10 or 15 mg. A missed dose can be taken within 4 days, otherwise skip it. In SURMOUNT-1 everyone started at 2.5 mg and stepped up every 4 weeks.

LABEL START2.5 mg weekly for 4 weeksLabel
LABEL STEP+2.5 mg after at least 4 weeksLabel
LABEL MAINTENANCE5, 10 or 15 mg weeklyLabel
LABEL MAXIMUM15 mg weeklyLabel
MISSED DOSETake within 4 days, otherwise skipLabel
COMMUNITY START2.5 mg weeklyCommunity
COMMUNITY HOLDStay lower longer if side effects buildCommunity

Label and trial amounts come from the sources below. Community amounts are what people report; they have not been tested.

Mixing

Vial10 mg
+
BAC water2 mL
=
Strength5 mg per mL

Brand pens and vials come ready to use. Mixing a research vial is community practice only.

Open the peptide calculator

What the research found

SURMOUNT-1 (2,539 adults with obesity, no diabetes, 72 weeks). Average body-weight change:

−15.0%5 mg weekly
−19.5%10 mg weekly
−20.9%15 mg weekly
−3.1%Placebo

Jastreboff AM et al., N Engl J Med 2022;387:205–16. Waist: −14.0 to −18.5 cm vs −4.0 cm on placebo.

Tirzepatide community experience

What users report. Not tested in trials.

Positive reports

  • Less food noise Constant thoughts about food often fade.
  • Steady weight loss Pace varies with dose, starting weight and diet.
  • Lower doses can work Some do well without fast step-ups.
  • Training and protein Lifters report better strength during weight loss.

Negative & mixed

  • Stomach trouble Nausea, constipation, diarrhoea, fatigue and sulfur burps during steps.
  • Eating too little Strong appetite loss makes calories, protein and fluids hard.
  • Plateaus A stall after months does not always call for a higher dose.

Tirzepatide stacking

Tirzepatide + protein and lifting

Most practical way to protect muscle and strength.

Tirzepatide + CJC-1295 / ipamorelin

Discussed for muscle. No trial shows added protection.

Tirzepatide + other GLP-1 drugs

Label advises against it. Do not combine.

Tirzepatide side effects & safety

Common

  • Nausea: 25–29% vs 8% on placebo (label, obesity trials).
  • Diarrhoea: 19–23% vs 8%.
  • Vomiting: 8–13% vs 2%.
  • Constipation: 11–17% vs 5%.
  • Hair loss: 4–5% vs 1%, tied to weight loss.
  • Mostly during step-ups.

Less common

  • Gallbladder disease and pancreatitis.
  • Dehydration-related kidney injury.
  • Serious allergic reactions reported after approval.
  • Thyroid C-cell tumours in rats; human risk unknown.

Precautions

  • Avoid with personal or family history of medullary thyroid cancer or MEN2.
  • Not for severe gastroparesis; take care with pancreatitis or gallstones.
  • Insulin or sulfonylureas raise low blood sugar risk.
  • Birth-control pills may work less well; add a barrier method for 4 weeks after each step.
  • Tell your doctor before surgery; slower stomach emptying raises aspiration risk.

Our verdict on Tirzepatide

Best-proven approved weight peptide; it beat semaglutide head-to-head. Hold the lowest dose that works and protect protein and training.

Tirzepatide FAQ

How much weight loss should I expect?

SURMOUNT-1: 15.0% (5 mg) to 20.9% (15 mg) at 72 weeks.

What happens if I stop?

SURMOUNT-4: on placebo people regained 14.0%; those continuing lost 5.5% more.

Does it cost muscle?

About 75% of lost weight was fat and 25% lean (SURMOUNT-1 scan, 160 people).

What if I miss a dose?

Take it within 4 days (96 hours). After that, skip and resume the schedule.

Sources

  • Zepbound and Mounjaro US prescribing information (dosing, warnings)
  • Jastreboff AM et al. N Engl J Med 2022;387:205–16 (SURMOUNT-1)
  • Zepbound US prescribing information, revised 08/2026 (dosing, adverse reactions, SURMOUNT-4, OSA studies)
  • Aronne LJ et al. N Engl J Med 2025;393:26 (SURMOUNT-5, vs semaglutide)
  • Aronne LJ et al. JAMA 2024;331:38 (SURMOUNT-4, stopping)
  • Jastreboff AM et al. N Engl J Med 2025;392:958 (SURMOUNT-1, 176 weeks, prediabetes)
  • Malhotra A et al. N Engl J Med 2024;391:1193 (SURMOUNT-OSA)
  • Frías JP et al. N Engl J Med 2021;385:503 (SURPASS-2)
  • Look M et al. Diabetes Obes Metab 2025;27:2720 (SURMOUNT-1 body composition)
  • Samms RJ et al. Mol Metab 2022;64:101550 (obese mice, brown fat)