Tirzepatide Peptide Protocol & Dosing

What it is

Tirzepatide is a dual GLP-1/GIP receptor agonist studied for type-2 diabetes and chronic weight management.

Evidence boundary

Human evidence exists for the studied indications.

Trial evidence

PMID 35658024 — Tirzepatide Once Weekly for the Treatment of Obesity.
PMID 38912654 — Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity.
PMID 39555826 — Tirzepatide for Heart Failure with Preserved Ejection Fraction and Obesity.
PMID 39536238 — Tirzepatide for Obesity Treatment and Diabetes Prevention.
PMID 41419618 — Efficacy of tirzepatide versus semaglutide in achieving therapeutic targets in type 2 diabetes: a post hoc analysis of the SURPASS-2 Trial.
PMID 42714458 — Tirzepatide and the Incidence of Atrial Fibrillation in Adults With Overweight or Obesity: An Updated Meta-Analysis of Randomized Controlled Trials.
PMID 42618523 — Major Adverse Liver Outcomes With Tirzepatide and Injectable Semaglutide in Adults With Overweight or Obesity and Type 2 Diabetes.
PMID 42729958 — Weight regain following discontinuation of glucagon-like peptide-1 receptor agonists in adults who are overweight or obese.

Preparation and measurement

Reconstitution: 30 mg vial + 2 mL BAC = 15 mg/mL.

Concentration matches.

Reference schedule

Reference schedule
Phase	Dose	Draw / measure	Frequency	Weekly total
Weeks 1–4 (titration)	2.5 mg	16.667 U (0.167 mL)	Once weekly	2.5 mg/week
Weeks 5–8	5 mg	33.333 U (0.333 mL)	Once weekly	5 mg/week
Weeks 9–12	7.5 mg	50 U (0.5 mL)	Once weekly	7.5 mg/week
Weeks 13–16	10 mg	66.667 U (0.667 mL)	Once weekly	10 mg/week
Weeks 17–20	12.5 mg	83.333 U (0.833 mL)	Once weekly	12.5 mg/week
Weeks 21+ (maintenance)	15 mg	100 U (1 mL)	Once weekly	15 mg/week

Weeks 1–4 (titration)

Dose: 2.5 mg
Draw / measure: 16.667 U (0.167 mL)
Frequency: Once weekly
Weekly total: 2.5 mg/week

Weeks 5–8

Dose: 5 mg
Draw / measure: 33.333 U (0.333 mL)
Frequency: Once weekly
Weekly total: 5 mg/week

Weeks 9–12

Dose: 7.5 mg
Draw / measure: 50 U (0.5 mL)
Frequency: Once weekly
Weekly total: 7.5 mg/week

Weeks 13–16

Dose: 10 mg
Draw / measure: 66.667 U (0.667 mL)
Frequency: Once weekly
Weekly total: 10 mg/week

Weeks 17–20

Dose: 12.5 mg
Draw / measure: 83.333 U (0.833 mL)
Frequency: Once weekly
Weekly total: 12.5 mg/week

Weeks 21+ (maintenance)

Dose: 15 mg
Draw / measure: 100 U (1 mL)
Frequency: Once weekly
Weekly total: 15 mg/week

Weekly totals apply only during the active phase.

Titration rules

The SURMOUNT-1 titration protocol — used in obesity trials — escalates every 4 weeks:
Weeks 1–4: 2.5 mg once weekly. Tolerability assessment dose.
Weeks 5–8: 5.0 mg once weekly. First therapeutic step.
Weeks 9–12: 7.5 mg once weekly.
Weeks 13–16: 10.0 mg once weekly. A common convention plateau here for 4–8 weeks before deciding whether to escalate.
Weeks 17–20: 12.5 mg once weekly.
Weeks 21+ (maintenance): 15.0 mg once weekly. SURMOUNT-1 maintenance dose.
SURPASS protocol (T2DM): Same titration, with maintenance often at 5, 10, or 15 mg depending on glycemic targets.
Lower-maintenance protocols: Some research protocols cap at 10 or 12.5 mg long-term — both produced significant weight loss in trials with fewer side effects than 15 mg.
Day-of-week timing: Same day each week. Half-life ~5 days. A common protocol dose Sunday or Monday so peak effect coincides with weekday meals.
Missed dose: ≤72h late, take when remembered. >72h, skip and resume next scheduled day.
Plateau approach: If weight loss stalls for 4+ weeks at a given step, consider escalating to the next step. If side effects are limiting, stay put and let the body adjust.
SURMOUNT-1: 20.9% weight reduction at 15 mg weekly over 72 weeks vs 3.1% placebo.
SURPASS-2 (T2DM): HbA1c reduction up to 2.46% at 15 mg.
Greater outcomes than single-agonist comparators in head-to-head trials.
Improvement in lipid profile and waist circumference reported alongside weight loss.
Nausea (most common, dose-dependent).
Diarrhea and vomiting (more common at higher doses).
Decreased appetite (intended effect).
Constipation in some protocols.
Rare: pancreatitis, gallbladder events.

Practical rules

Aggressive hydration — incretin agonists blunt thirst sensation.
Protein 1.0–1.6 g/kg/day preserves lean mass during weight loss.
Resistance training 2–3×/week mitigates muscle loss in caloric deficit.
Avoid high-fat or large-volume meals around dosing.
Pace meals slowly; eat to 80% fullness rather than past it.
Inject subcutaneously into abdomen (away from navel), outer thigh, or upper arm.
Rotate sites with each weekly dose.
90° angle with short insulin needles (4–8 mm).
Bring vial to room temperature 15 min before injecting.
Hold 5 seconds after full plunger depression before withdrawing.