(See also Drug Use and Abuse.)
Amphetamines increase alertness, enhance physical performance, and produce euphoria and a sense of well-being.
Amphetamines suppress appetite and some people misuse amphetamines to lose weight.
An overdose can cause extreme agitation, delirium, and a life-threatening heart attack or stroke.
Urine tests can detect most amphetamines.
For an overdose, treatment involves sedatives, blood pressure–lowering drugs and sometimes cooling treatments.
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, often referred to as a substance use disorder.
The following are some immediate effects of amphetamine use:
Amphetamines may produce a feeling of well-being, euphoria, and loss of inhibitions. Also, people sweat profusely, and their pupils are dilated.
Binge usage (perhaps over several days) eventually causes extreme exhaustion and a need for sleep.
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.
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).
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 over several days or weeks 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.
Methamphetamine users have a high rate of teeth grinding (bruxism) and severe tooth decay affecting numerous teeth. The causes include decreased salivation, corrosive substances in the smoke, and poor oral hygiene—called "meth mouth."
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 may not detect methamphetamine and methylphenidate.
Other tests, such as electrocardiography, computed tomography, and blood tests, may be done to check for complications.
After an overdose, treatment may include
Benzodiazepines (a group of sedative drugs), such as lorazepam, are given intravenously to people with severe symptoms such as high blood pressure, extreme agitation, or seizures.
Drugs for high blood pressure, such as labetolol or hydralazine, are given intravenously if blood pressure remains high.
Cooling treatments, such as wetting the patient and blowing air over the skin or using special cooling blankets may be needed to correct hyperthermia.
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.