GHS hazard statement
H251: Self-heating; may catch fire
- H251
- Physical hazards
- Danger
H251 means “Self-heating; may catch fire”. It is a GHS hazard statement for Self-heating substances and mixtures (Category 1), shown with GHS02 under the signal word “Danger”.
Hazard class and category
| Hazard class | Category | Pictogram | Signal word | UN transport class |
|---|---|---|---|---|
| Self-heating substances and mixtures | Category 1 |  | Danger | Div 4.2 |
What H251 means
Self-heating substances and mixtures are solids or liquids, other than pyrophoric ones, that can heat up by reaction with air without any outside energy supply. They may ignite only in large amounts and after long periods (hours or days).
Heat can build up inside a pile, bag or drum until the material catches fire, especially in large quantities.
What to do
Keep in small quantities and in cool, well-ventilated storage, avoid stacking in large piles, keep away from heat, and follow the maximum storage quantities and temperatures given by the supplier.
This is general guidance for the hazard class. The safety data sheet for your product always takes precedence.
Precautionary statements for H251
The GHS lists these precautionary statements for this hazard. Which ones appear on a label depends on the supplier's classification.
| Code | Statement |
|---|---|
| P235 | Keep cool. |
| P280 | Wear protective gloves/protective clothing/eye protection/face protection/hearing protection/... |
| P407 | Maintain air gap between stacks or pallets. |
| P410 | Protect from sunlight. |
| P413 | Store bulk masses greater than ... kg/...lbs at temperatures not exceeding ... °C/...°F. |
| P420 | Store separately. |
Chemicals carrying H251
No chemicals in our database are classified with H251 yet.
H251 frequently asked questions
What does H251 mean?
H251 means "Self-heating; may catch fire". It is a GHS hazard statement in the physical hazards group, covering Self-heating substances and mixtures (Category 1).
Which pictogram goes with H251?
H251 is shown with GHS02 (Flame).
What signal word goes with H251?
The signal word for H251 is "Danger".
Which precautionary statements go with H251?
The GHS data lists 6 precautionary statements for H251, including P235, P280, P407, P410, P413. They cover prevention, response, storage and disposal. The full list is on this page.
Hazard statements describe the hazard of a classified substance or mixture. The classification of a specific product can differ, so use the supplier's SDS.
https://pubchem.ncbi.nlm.nih.gov/ghs/ghscode_10.txt (UN GHS Revision 10, retrieved 2026-10-12)