Stimulants (from the Latin word stimulare, meaning "to goad, torment, incite") are drugs which produce a quick temporary increase of energy in the user. Tobacco and caffeine are the two most popular stimulants, but most of the drugs in this category are amphetamines or similar preparations.

Stimulants are drugs which excite or speed up the central nervous system. They are generally used for their ability to increase alertness and endurance, to keep users awake for a long period of time, to decrease appetite, and to produce feelings of well-being and euphoria. They have only limited medical application. Stimulants can produce severe psychological dependence. The psychological dependence produced by cocaine, for example is believed to be more powerful than for any other known drug. Stimulants, including nicotine and caffeine, can produce physical dependence.


Stimulants can cause increased heart and respiratory rates, elevated blood pressure, dilated pupils, and decreased appetite. In addition, users may experience sweating, headache, blurred vision, dizziness, sleeplessness, and anxiety. Extremely high doses can cause a rapid or irregular heartbeat, tremors, loss of co-ordination, and even physical collapse. An amphetamine injection creates a sudden increase in blood pressure that can result in stroke, very high fever, or heart failure.

In addition to the physical effects, users report feeling restless, anxious, and moody. Higher doses intensify the effects. Persons who use large amounts of amphetamines over a long period of time can develop an amphetamine psychosis that includes hallucinations, delusions, and paranoia. These symptoms usually disappear when drug use ceases.

Types of stimulants