Amphetamines are drugs such as dextroamphetamine and benzedrine. Amphetamines were originally developed to treat asthma, sleep disorders (narcolepsy) and hyperactivity. In 1920, a drug called "ephedrine" was used to treat asthma. In China, the ma huang plant (Ephedra vulgaris) had been used for centuries to treat people with asthma. It is no wonder that the plant worked...the ma huang plant contains ephedrine. In 1932, synthetic ephedrine was sold "over-the-counter" and was available without a prescription until 1954. During World War II, soldiers and pilots were given amphetamines to keep them awake and alert.

Amphetamine Effects on the Nervous System

Amphetamines are stimulants of the central nervous system and sympathetic division of the peripheral nervous system. It appears that the main action of amphetamines is to increase the synaptic activity of the dopamine and norepinephrine neurotransmitter systems. Amphetamines act:

  1. at axon terminals to release dopamine.
  2. at synapses to block dopamine reuptake.
  3. at vesicles to inhibit the storage of dopamine.
  4. to prevent the enzymatic destruction of dopamine.

All of these actions result in more dopamine in the synaptic cleft where it can act on receptors.

Many of the effects of amphetamines are similar to cocaine. Addiction to and withdrawal from amphetamines are both possible. Amphetamine use also causes tolerance to its effects. This means that more and more amphetamine must be used to get "high." Amphetamine withdrawal is characterized by severe depression and fatigue. Users will go to extreme measures to avoid the "downer" that comes when the effect of amphetamines wears off.

Short-term effects of amphetamine use include:

  • Increased heart rate
  • Increased blood pressure
  • Reduced appetite
  • Dilation of the pupils
  • Feelings of happiness and power
  • Reduced fatigue
Long term use of amphetamines can result in:
  • Insomnia, restlessness
  • "Paranoid psychosis"
  • Hallucinations
  • Violent and aggressive behavior
  • Weight loss
  • Tremors


Take a short on-line, interactive quiz about amphetamines, cocaine and marijuana.


For more information about amphetamines, see:
  1. Amphetamines - National Clearinghouse for Drug and Alcohol Information
  2. Indiana Prevention Resource Center
  3. Methamphetamine Abuse from the National Institute on Drug Abuse
  4. Methamphetamine May Cause Long-Lasting Brain Damage



GO TO: Alcohol Amphetamines Caffeine Cocaine
Heroin Inhalants LSD Marijuana
Nicotine Ecstasy Rohypnol 1,4-Butanediol
GHB Barbiturates PCP Hallucinogenic Mushrooms

BACK TO: Drug Effects on
the Nervous System
Exploring the Nervous System Table of Contents

Send E-mail

Get Newsletter

Search Pages

Donate to
Neuroscience for Kids