Glossary / Health hazards
Narcotic effects
Narcotic effects are depression of the central nervous system caused by exposure to a chemical, producing symptoms such as drowsiness, dizziness, headache, confusion and, at high exposure, unconsciousness. They are usually reversible after exposure ends.
Explanation
Many solvent vapors act on the brain much like an anesthetic. Early signs resemble intoxication: light-headedness, slowed reactions, poor coordination and a headache. Higher concentrations can cause collapse and breathing failure. Because judgment is affected, a worker may not recognize that something is wrong.
The practical hazard is as much about accidents as poisoning. A dizzy worker may fall, drop a container or be unable to leave a confined area. Narcotic effects are therefore a particular concern in tanks, pits and other confined spaces where vapor concentrations can build up.
In the GHS this effect is part of specific target organ toxicity from a single exposure. The hazard statement H336 reads may cause drowsiness or dizziness, and it is paired with the exclamation mark pictogram and the signal word Warning. Repeated exposure can also contribute to lasting nervous system effects, which fall under repeated-exposure classification.
Narcotic effects should not be mistaken for asphyxiation. Narcotic chemicals act directly on the nervous system, while asphyxiants cause harm by lowering the oxygen available to the body. Both can occur in the same space.
What to do and watch for
- Treat headache or drowsiness while using solvents as a sign of overexposure and move to fresh air.
- Increase ventilation or use local exhaust when working with volatile solvents indoors.
- Never enter a tank or pit with solvent vapors without a permit, testing and a rescue plan.
Where it appears on an SDS
- Section 2: Hazard identification. The H336 statement and its target organ toxicity category are listed with the exclamation mark pictogram.
- Section 11: Toxicological information. Symptoms such as dizziness, drowsiness or nervous system depression from single exposure are described here.
SDS content and wording vary by supplier. This page is general reference and does not replace the current SDS for your product.
Related terms
- Target organ
- Inhalation exposure
- Asphyxiant
- Confined space
- Acute toxicity
- Local exhaust ventilation (LEV)