The Nitrites used in medicine are certain salts or esters of nitrous acid and possess a common pharmacologic action. This group also includes certain organic nitrates which are reduced to nitrites in the organism. The chief members are amyl nitrite, sodium nitrite and glycerol nitrate (glyceryl trinitrate or nitroglycerin).

The characteristic action of this group is vasodilatation with a fall of the blood-pressure. The members differ chiefly in the rapidity and duration of their effects, amyl nitrite being the quickest, though its action is of correspondingly short duration.