PRTCL.Sign in
What to Expect

Why is my heart racing on retatrutide?

Updated 2026-05-02

Heart rate increases are expected on retatrutide. This is because retatrutide activates three receptors at once - GLP-1, GIP, and glucagon - and glucagon directly stimulates the heart. In the Phase 2 TRIUMPH trial, heart rate increases peaked around week 24 and then came back down. Phase 3 TRIUMPH-4 averaged a 5 to 7 bpm increase at the 12 mg dose, with overall blood pressure actually improving. Call a doctor if your resting heart rate stays above 100 bpm or if you have palpitations with chest pain or dizziness.

IfIf your resting heart rate has gone up 5 to 10 bpm since starting retatrutide
Thenthen this is expected - monitor and report to your prescriber
IfIf resting heart rate stays above 100 bpm
Thenthen contact your prescriber; dose reduction may be appropriate
IfIf you have palpitations with chest pain, shortness of breath, or fainting
Thenthen go to the ER
Key facts
  • Phase 2 TRIUMPH (Jastreboff et al., NEJM 2023, NCT04881760): dose-dependent increases in heart rate peaked at 24 weeks and declined thereafter; 338 adults with obesity without type 2 diabetes
  • Phase 3 TRIUMPH-4 (68 weeks, n=751 on 12 mg): heart rate +5 to 7 bpm average; systolic BP -8.0 mmHg; diastolic BP -4.3 mmHg
  • Overall cardiovascular picture in TRIUMPH-4 was positive despite the heart rate increase
  • Mechanism: glucagon receptor activation directly increases heart rate (chronotropy); semaglutide and tirzepatide do not activate glucagon receptors
Get more like this

Your guided peptide companion.

PRTCL walks beginners through their first peptide with confidence - guided reconstitution, dose calculation, vial tracking, and answers to questions like this one. Built for first-timers, useful for everyone.

  • · Guided walkthrough for your first dose
  • · Dose calculator that does the math for you
  • · Vial inventory and dose log tracking
  • · Library of physician-vetted protocols

Free to start. Sign in if you already have an account.

PRTCL is educational. Always talk to a licensed provider about your situation.