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Amphetamines am-ˈfet-ə-ˌmēn, -mən

By Patrick G. O’Connor, MD, MPH, Professor of Medicine; Chief, Section of General Internal Medicine, Yale University School of Medicine

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  • Amphetamines increase alertness, enhance physical performance, and produce euphoria and a sense of well-being.

  • An overdose can cause extreme agitation, delirium, and a life-threatening heart attack or stroke.

  • Urine tests can detect most amphetamines.

  • For most people, treatment involves reassurance and a calm environment, but sedatives such as benzodiazepines may be needed.

Amphetamines include amphetamine and its many variants such as methamphetamine (speed or crystal meth) and methylenedioxymethamphetamine (MDMA, Ecstasy, or Adam). Methamphetamine is the most commonly used amphetamine in the United States. Use of MDMA is growing in popularity. Amphetamines are usually taken by mouth but can be snorted, smoked, or injected.

Because some amphetamines are widely used as treatment for attention-deficit/hyperactivity disorder, obesity, and narcolepsy, there is a ready supply that can be diverted to illegal use. Some amphetamines are not approved for medical use and are manufactured and used illegally.

Some amphetamine users are depressed and seek the mood-elevating effects of these stimulants to temporarily relieve the depression. Others use them during high-energy activities. Amphetamines cause more dopamine to be released in the brain. (Dopamine is a neurotransmitter, a substance that helps nerve cells communicate.) This effect is the likely cause of mood elevation. MDMA differs from other amphetamines in that it also interferes with the reuptake of serotonin (another neurotransmitter) in the brain. Amphetamine users frequently develop dependence.

Did You Know...

  • High doses of amphetamines may raise body temperature to dangerous levels.


Immediate Effects

Amphetamines increase alertness, reduce fatigue, heighten concentration, decrease appetite, and enhance physical performance. They may produce a feeling of well-being, euphoria, and loss of inhibitions. Also, people sweat profusely, and the pupils are dilated. High doses (overdose) increase blood pressure and heart rate. These increases may be life threatening. People may become extremely paranoid, violent, and out of control.

Binge usage (perhaps over several days) eventually causes extreme exhaustion and a need for sleep.


People may become delirious. Heart attacks have occurred, even in healthy young athletes. Blood pressure may become so high that a blood vessel in the brain ruptures, causing a stroke. Other effects include dizziness, nausea, vomiting, diarrhea, seizures, and a life-threatening high body temperature (hyperthermia).

Complications are more likely in the following situations:

  • When drugs such as MDMA are used in warm rooms with little ventilation

  • When the user is very active physically (for example, when dancing fast)

  • When the user sweats heavily and does not drink enough water to restore lost fluids, resulting in dehydration

Long-Term Effects

People who habitually use amphetamines rapidly develop tolerance as part of dependence. They need to use more and more to get the same effect. The amount ultimately used may be more than several times the original dose. Most people using very high doses become confused and psychotic because amphetamines can cause severe anxiety, paranoia, and a distorted sense of reality. Psychotic reactions include hearing and seeing things that are not there (auditory and visual hallucinations) and false beliefs (delusions), such as a feeling of having unlimited power (omnipotence) or of being persecuted (paranoia). Memory may be affected. Confusion, memory loss, and delusions may last for months. Although these effects can occur in any user, people with a mental health disorder, such as schizophrenia, are more vulnerable to them.

Users have a high rate of severe tooth decay affecting numerous teeth. The causes include decreased salivation, corrosive substances in the smoke, and poor oral hygiene—called meth mouth.

Withdrawal Symptoms

When an amphetamine is suddenly stopped, symptoms vary. People dependent on amphetamines become tired or sleepy—an effect that may last for 2 or 3 days after stopping the drug. As a result, they are more likely to be injured. Some people are extremely anxious and restless, and some, especially those with a tendency toward depression, become depressed when they stop. They may become suicidal but may lack the energy to attempt suicide for several days.


Doctors base the diagnosis on symptoms in people known to have taken amphetamines. If the diagnosis is unclear, urine tests may be done, but the test usually does not detect MDMA. Other tests, such as electrocardiography, computed tomography, and blood tests, may be done to check for complications.


For most people, treatment involves reassurance and a calm environment.

For people with severe symptoms such as high blood pressure, extreme agitation, or seizures, doctors usually give benzodiazepines (sedative drugs), such as lorazepam, intravenously. If blood pressure remains high, nitrates or other antihypertensive drugs are given intravenously.

Treatment may be needed to correct dehydration, hyperthermia, and other complications.

During drug withdrawal, long-term users may need to be hospitalized so that they can be observed for suicidal behavior. Antidepressants may be given if depression persists. Otherwise, no treatment is generally needed for people experiencing withdrawal.

Cognitive-behavioral therapy (a form of psychotherapy) helps some people stay free of amphetamines.

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* This is the Consumer Version. *