Some substances when taken into the body in fairy large quantities can be dangerous to health or can cause death. Such substances are poisons.

Poisons get into body by swallowing or by breathing poisonous gases, or by injection.

Sometimes acids, alkalis, disinfectants etc., are swallowed by mistake. They burn the lips, tongue, throat, and food passage and stomach and cause great pain. Other swallowed poisons cause vomiting, pain and letter on diarrhea. Poisonous fungi, berries, metallic poisons and stale food belong to the latter group some swallowed poisons affect the nervous system. To this group belong (a) alcoholic (methylated spirit, wine, whisky etc.) when taken in large quantities, and (b) tables for sleeping, tranquilizers, and pain killing drugs (aspirin or largectil). All these victims must be considered as seriously ill .The symptoms are either delirium or fits or come (unconsciousness). Some poisons act on nervous system-(belladonna, strychnine).