Stimulants are drugs that can reduce fatigue, suppress appetite, and increase alertness and aggressiveness. They stimulate the central nervous system, increasing your heart rate, blood pressure, body temperature and metabolism.

The most common stimulants include caffeine and amphetamines (Dexedrine, Benzedrine). Cold remedies often contain the stimulants ephedrine, pseudoephedrine hydrochloride (Sudafed) and phenylpropanolamine (Acutrim). Street drugs such as cocaine and methamphetamine also belong to this group.

Although stimulants can boost physical performance and promote aggressiveness on the field, they have side effects that can impair athletic performance. Nervousness and irritability make it hard to concentrate on the game, and insomnia can prevent an athlete from getting needed sleep. Athletes may become psychologically addicted or develop a tolerance so that they need greater amounts to achieve the desired effect.

Other side effects include:

Heart palpitations

Heart rhythm abnormalities

Weight loss

Mild hypertension

Hallucinations

Convulsions

Brain hemorrhage

Heart attack and other circulatory problems