Reference summary — not medical advice or a personal risk estimate.
Phenobarbital
Quick answer
Classified as Group 2B — possibly carcinogenic, based on limited evidence in humans, alongside stronger evidence in animals. Prescription medication. Risk relates to exposure from medical use.
Summary
Classified by IARC as Group 2B — possibly carcinogenic to humans. Evidence is limited. (Vol Sup 7, 79, 2001)
What's not established
This classification reflects limited evidence in humans, often paired with stronger evidence in animals. It does not establish how strong the human evidence would look on its own, a safe exposure threshold, or your personal risk from a given level of exposure.
Regional relevance
global
Documented in these products
Presence in a product category doesn't imply the product causes cancer. Click each to see the source and context.
Evidence sources
Every claim on this page traces back to one of these. Click through to read the primary document yourself.
Primary sources
IARC
IARC Monographs — Agents Classified Alphabetically (Vols 1–123)
Last reviewed: October 2026
Official reference list
A government list some readers use alongside the primary evidence. Meyron is not affiliated with it. A chemical being listed does not by itself describe a risk from any particular product.
- California Prop 65 list
State of California's list of chemicals known to cause cancer or reproductive harm.