The numbering system
- H2xx — physical hazards (flammable, explosive, oxidising, compressed).
- H3xx — health hazards (toxic, corrosive, carcinogenic, sensitising).
- H4xx — environmental hazards (aquatic toxicity).
Some jurisdictions add supplemental codes: EUH0xx (EU-specific hazards like "explosive when dry"), AUH0xx (Australian additions). These sit next to the H-codes on Section 2 of the SDS.
Most common H-codes
| Code | Statement |
|---|---|
| H200 | Unstable explosive |
| H220 | Extremely flammable gas |
| H222 | Extremely flammable aerosol |
| H225 | Highly flammable liquid and vapour |
| H226 | Flammable liquid and vapour |
| H271 | May cause fire or explosion; strong oxidiser |
| H272 | May intensify fire; oxidiser |
| H290 | May be corrosive to metals |
| H301 | Toxic if swallowed |
| H302 | Harmful if swallowed |
| H311 | Toxic in contact with skin |
| H314 | Causes severe skin burns and eye damage |
| H315 | Causes skin irritation |
| H317 | May cause an allergic skin reaction |
| H318 | Causes serious eye damage |
| H319 | Causes serious eye irritation |
| H330 | Fatal if inhaled |
| H332 | Harmful if inhaled |
| H334 | May cause allergy or asthma symptoms if inhaled |
| H335 | May cause respiratory irritation |
| H336 | May cause drowsiness or dizziness |
| H340 | May cause genetic defects (mutagen) |
| H350 | May cause cancer (carcinogen) |
| H360 | May damage fertility or the unborn child |
| H370 | Causes damage to organs |
| H372 | Causes damage to organs through prolonged exposure |
| H400 | Very toxic to aquatic life |
| H410 | Very toxic to aquatic life with long-lasting effects |
Full list: UN GHS Rev. 10, Annex 3. This table shows the ~30 codes covering more than 90% of commercial products.