Most solvents used recreationally are central nervous system depressants: this means they slow down operation in certain areas of the brain. Volatile nitrites (amyl nitrite, butyl nitrite and isobutyl nitrite) dilate blood vessels and cause a brief drop in blood pressure. However, the ‘high’ experienced can also be as a direct result of the lack of oxygen reaching the brain, a form of asphyxia. When used excessively, this can result in unconsciousness and a risk of brain damage.
When inhaled, solvents enter the bloodstream directly from the lungs and rapidly reach the brain and other organs. Some are broken down and excreted through the kidneys, ultimately being passed out in urine; however others are exhaled unchanged through the lungs. As a result, it is sometimes possible to smell the original solvent on the breath of the user for several hours following use.