Tirzepatide (Mounjaro/Zepbound)
Dual agonist (GLP-1 / GIP)
Also known as Tirzepatide
Typical dose
2.5–15 mg weekly
once weekly · SubQ · titrate every 4 wks
Half-life
~5 days
What is Tirzepatide (Mounjaro/Zepbound)?
Dual GLP-1/GIP agonist. Even more potent than semaglutide for weight loss.
How Tirzepatide (Mounjaro/Zepbound) works
Co-activates GLP-1 and GIP receptors in a synergistic fashion — GIP activation enhances the appetite-suppressing and metabolic effects of GLP-1 beyond what either receptor achieves alone.
Benefits & uses
- Superior weight loss vs semaglutide
- Blood sugar control
- Cardiovascular benefits
- Appetite suppression
- Dual receptor action
- Major weight loss (~18–23% in trials)
- Strong blood-sugar control
- Appetite reduction
- May cause fewer GI effects than equipotent semaglutide (GIP effect)
Common uses: Weight loss, diabetes management, body composition.
Tirzepatide (Mounjaro/Zepbound) dosage
- Typical dose
- Typical: start 2.5 mg/week SubQ, titrate every 4 weeks (2.5→5→7.5→10→12.5→15 mg/week). Once weekly.
- Protocol notes
- Start 2.5mg/week, titrate to 5-15mg/week over 20+ weeks. Titrate slowly.
Tirzepatide (Mounjaro/Zepbound) half-life
~5 days (once-weekly dosing)
Tirzepatide (Mounjaro/Zepbound) side effects
Similar to semaglutide. Nausea, GI upset, potential gallstones.
- Nausea and vomiting (especially during titration)
- Diarrhea
- Constipation
- Hypoglycemia (when combined with insulin or sulfonylureas)
- Pancreatitis risk
- Gallstones
- Injection site reactions
- Nausea (up to ~32%)
- Diarrhea (~23%)
- Vomiting (~12%)
- Constipation (~11%)
- Fatigue
- Injection-site reactions
Warnings & monitoring
- Prescription only
- GI side effects — titrate slowly
- Black box warning: thyroid C-cell tumors in rodents
- Contraindicated in MTC history
- Muscle loss risk — prioritize protein and training
- Titrate slowly — GI effects worst on initiation/dose increases
- Class risks: pancreatitis, gallbladder disease, gastroparesis/obstruction
- Boxed warning: medullary thyroid carcinoma / MEN2 — contraindicated with that history
- Not for pregnancy
- Switching between GLP-1 agents without proper titration raises adverse-event risk
Preparation & storage
- Preparation
- Mix a 10 mg vial with 1 mL bac water → 10 mg/mL. A 2.5 mg dose = 0.25 mL = 25 units. Start 2.5 mg/week, titrate up.
- Reconstitution
- Reconstitute a 10 mg vial with 1 mL BAC water → 10 mg/mL. A 2.5 mg dose = 0.25 mL = 25 units on a U-100 syringe.
- Storage
- Refrigerate (2–8 °C). After first use: up to 21 days at room temperature. Protect from light.
Tirzepatide (Mounjaro/Zepbound) interactions
with Retatrutide
Avoid · severeTirzepatide (GLP-1/GIP dual) and Retatrutide (GLP-1/GIP/glucagon triple) share two overlapping receptor targets — concurrent use significantly amplifies adverse effects.
Timing: Do not use concurrently
with Semaglutide
Avoid · severeBoth are GLP-1 receptor agonists; concurrent use compounds GI toxicity and pancreatic stress with no additive efficacy.
Timing: Never combine
with Semaglutide
Avoid · severeThese are both GLP-1 agonists from the same drug class; combining them offers no additional efficacy but substantially increases the risk of pancreatitis and GI complications.
Timing: Do not use concurrently; choose one agent
with BPC-157
CompatibleDual-agonist GLP-1/GIP creates more pronounced GI stress than mono-agonists; BPC-157 supports the gastric mucosa under that load.
Timing: Concurrent — BPC-157 daily for the duration of GLP-1 use
with Testosterone
Compatible · lowTirzepatide (GIP/GLP-1 dual agonist) used for weight loss or metabolic health alongside TRT. Testosterone helps preserve lean mass during aggressive caloric restriction from tirzepatide.
Timing: Tirzepatide weekly; testosterone per protocol
Commonly stacked with
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