Also known as amyl, butyl, isobutyl nitrite (collectively known as alkyl nitrites).

Amyl nitrite in the past was used medically to ease the chest pain caused by angina pectoris. When inhaled the drug causes the dilation of blood vessels, allowing more blood to reach the heart. The drug also causes a rush of blood to the brain, a speeded-up heartbeat, the relaxation of muscle tissue and an intense high lasting just a few minutes. It is for these reasons that sniffing amyl nitrite and a related compound, butyl nitrite, became popular amongst gay men both in gay clubs and during sex.

The drug is used to intensify pleasure whilst dancing and whilst having sex. Sniffing poppers also relaxes the anal sphincter muscle, allowing anal intercourse to take place more easily. Use of poppers is not just restricted to gay men, however; a recent UK survey found that 20% of 16 year-olds claimed to have used nitrites, and it is frequently used on the club scene.

After-effects of sniffing poppers may include headaches, skin rashes, weakness, sinus pain, burns if the liquid comes into contact with the skin, and nausea. People with a history of heart trouble or anaemia should avoid using the drug, as should those with breathing problems, or glaucoma. In extreme cases excessive use of poppers can lead to methaemoglobulinemia, in which the lips and skin take on a blue tinge, and vomiting, shock and unconsciousness may follow. Deaths have been reported as a consequence of this condition.

Amyl nitrite is very rarely used in medicine these days but is controlled under the Medicines Act (1968). Possession is not illegal but supply can be an offence. The sale of poppers without a prescription was found to be illegal following a prosecution brought by the Royal Pharmaceutical Society against several sex shops which sold poppers. However, the law has not yet changed, although a recent European Union directive and a decision of the Medicines Control Agency (who administers the Medicines Act) means that any substance on sale with a psychoactive or mood-altering effect could be classed as a medicine and so be controlled under the Medicines Act.

Poppers may have long-term carcinogenic effects, according to studies in animals, but some researchers have suggested that poppers are excreted from the body very quickly after use. Any long-term carcinogenic effect in humans remains to be established.

Poppers should not be combined with the anti-impotence drug Viagra since this can lead to loss of blood pressure and could potentially be fatal.