# Retatrutide safety and side effects based on trial evidence

> Side-effect profile of investigational retatrutide from Phase 2 and Phase 3 trials: gastrointestinal effects, heart rate, cautions and unknowns.

Canonical: https://yezz.co.uk/safety-and-side-effects · Last reviewed: 2026-09-11 · Author: Nick Johnson, Independent Prescription Pricing Analyst, Medstack Ltd

## Key facts
- Most common effects: dose-related nausea, vomiting, diarrhoea and constipation — worst during dose step-ups, mostly settling with time.
- Trials recorded a small early rise in heart rate that partially returned to baseline — a monitoring item linked to the glucagon component, not a demonstrated harm.
- Class cautions: personal/family history of medullary thyroid carcinoma or MEN2, pancreatitis history, gallbladder disease, pregnancy, type 1 diabetes.
- Genuine unknowns: safety beyond ~2 years, cardiovascular outcomes (TRIUMPH-Outcomes, ~2029) and rare events.
- Trial data says nothing about unregulated vials bought online — those have no screening, no monitoring and no verified contents.

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Cite as: Nick Johnson. "Retatrutide safety and side effects based on trial evidence". Yezz, 2026-09-11. https://yezz.co.uk/safety-and-side-effects