Amphetamine is a powerful stimulator of the central nervous system. It is used to treat some medical conditions, but it is also highly addictive, with a history of abuse.

Stimulants such as amphetamine (Adderall) and methylphenidate (Ritalin and Concerta) are used to treat attention deficit hyperactivity disorder (ADHD). Used under prescription, stimulants can be safe and effective.

Amphetamine sulphate, or speed, is also used for recreational and non-medical purposes. It can lead to euphoria, and it suppresses the appetite, which can lead to weight loss. Used outside the medical context, stimulants can have severe adverse effects.

In this article, we will look at amphetamine's medical uses, its side effects, and how it is misused.

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Amphetamines come in different forms. They are used to treat ADHD and as a recreational drug.

Amphetamine activates receptors in the brain and increases the activity of a number of neurotransmitters, especially norepinephrine and dopamine.

Dopamine is associated with pleasure, movement, and attention.

Amphetamine has been trialed for a wide variety of conditions. Now, it is mainly used to treat ADHD, and, rarely, depression. In the past, it has been used to treat narcolepsy and to help with weight loss, but this is less common now.

Attention deficit hyperactivity disorder

ADHD is characterized by hyperactivity, irritability, mood instability, attention difficulties, lack of organization, and impulsive behaviors.

It often appears in children, but it can continue into adulthood.

Amphetamines reverse some of these symptoms and have been shown to improve brain development and nerve growth in children with ADHD.

Long-term treatment with amphetamine-based medication in children appears to prevent unwanted changes in brain function and structure.

Scientists carrying out a review of 20 studies concluded that stimulants are probably helpful for people with ADHD.

They found that the brain structures of people who took stimulants for ADHD were more likely to resemble the brain structures of people without the condition than to resemble those with ADHD who did not use the drugs.

A review published in Cochrane in 2011 suggested that adults with ADHD might benefit from short-term use of amphetamines, but that they were unlikely to persist with the treatment because of adverse effects. Those who use mixed amphetamine salts, however, were more likely to continue with the treatment.

Narcolepsy

A person with narcolepsy will experience excessive daytime sleepiness and irresistible sleep episodes, called "sleep attacks."

In a person with this condition, strong emotions can trigger a sudden loss of muscle tone, or cataplexy, which causes a person to collapse and possibly fall down. It also involves frequent and unexpected bouts of sleep.

Amphetamines and amphetamine derivatives have been used in the past to treat narcolepsy.

Due to concerns over their side effects, however, amphetamines are increasingly being replaced by modafinil, a medication that promotes wakefulness.

Obesity

Under the name Benzedrine, amphetamines were first used to treat obesity in the 1930s, due to their appetite-suppressing capabilities.

Fears of the drug's side effects and its potential for addiction and abuse caused them to fall out of favor for this purpose. In the 1950s, reports of malnutrition, psychosis, and depression on withdrawal caused doctors to stop prescribing amphetamines for weight loss.

Currently, medical professionals do not recommend using amphetamines and their derivatives to help reduce obesity.

However, in 2015, after carrying out a small study, researchers suggested that dexamphetamine might be a safe and effective way of boosting people's motivation for lifestyle changes that can lead to weight loss.

They proposed a 6-month use of the drug to help people who have not responded to other treatment to improve their diet and increase exercise levels. This, they say, could help curb obesity and related complications, such as diabetes and cardiovascular disease.

Depression

From the 1930s, amphetamine was used to treat affective disorders, obsessive-compulsive disorder (OCD), and schizophrenia.

However, in the 1950s and 1960s, amid growing concern about its adverse effects, it was replaced by newly available antidepressants.

In rare cases, amphetamines are used alongside standard antidepressants to treat some types of depression that do not respond to other treatments, especially in people who also experience fatigue and apathy.

In a study that followed 65 patients taking amphetamines alongside normal medication, 38 "showed significant improvement, in particular with respect to energy, mood, and psychomotor activity."

According to the authors, side effects were minimal, and no drug dependency was seen.

Amphetamine can produce many side effects, ranging from mild to severe.

Physical side effects include:

  • low or high blood pressure
  • Raynaud's phenomenon, where there is reduced blood flow to the extremities
  • erectile dysfunction, and especially frequent or persistent erections
  • rapid heart rate
  • abdominal pain
  • loss of appetite, nausea, and weight loss
  • acne, rash, hives
  • blurred vision
  • dry mouth
  • teeth grinding
  • nosebleed
  • profuse sweating
  • nasal congestion
  • increased likelihood of seizures for susceptible individuals
  • tics
  • faster, deeper breaths, especially in those with other lung conditions
  • difficulty urinating

There may also be psychological effects.

These include:

  • increased alertness and focus
  • apprehension, anxiety, irritability, and restlessness
  • mood swings
  • insomnia
  • changes in libido
  • grandiosity, or an exaggerated sense of one's own importance
  • obsessive behaviors

In rare cases, psychosis may occur

People who follow the prescribed, therapeutic dose are unlikely to experience severe adverse effects.

There have been fears that long-term use of amphetamines for ADHD could affect brain development, prevent physical growth, and increase the risk of drug abuse later in life. However, animal studies have suggested that this is unlikely.

Effects on child growth

There is evidence that amphetamine use to treat ADHD could slow growth in children. Minor effects on the cardiovascular system, including a rise in heart rate and blood pressure, may have long-term effects.

However, some studies show that any reduction in growth speed may be caught up by a "growth rebound" once the drug has stopped being taken.

More studies are needed to confirm whether amphetamines affect growth.

Amphetamine is used as a recreational drug. People take it to boost libido, increase wakefulness, improve cognitive control, enhance sociability, and induce euphoria.

It can also speed up reaction times, increase muscle strength, and reduce fatigue.

Unwanted effects of 'speed'

When amphetamines are used at higher doses and through routes that are not prescribed by a doctor, they can have severe adverse effects. Dopamine levels in the brain can rise quickly, and to a great extent.

Overuse and repeated abuse can lead to:

  • psychosis and delusions
  • feelings of paranoia and hostility
  • cardiovascular problems, including stroke
  • reduction in cognitive ability
  • breakdown of muscle and malnutrition

Withdrawal symptoms include depression and sleep disturbances.

People who crush and inject a tablet may have blockages in their small blood vessels, as some of the components do not break down.

Amphetamine substitutes

Other street drugs that are based on the structure of amphetamine include methamphetamine, cathinone, ephedrine, MDMA (ecstasy), and 2,5-Dimethoxy-4-methylamphetamine (DOM).

These drugs can have a wide variety of overlapping effects that broadly fit into three categories:

  • psychoanaleptic, or having an arousing effect
  • hallucinogenic, causing visual, auditory, or other types of hallucination and perceptual anomalies
  • empathogen, increasing feelings of "oneness," empathy, and emotional openness

These drugs are made illegally, and there is no control over their contents. For this reason, a person can easily consume something they do not expect to consume. This can be hazardous, and, in some cases, fatal.

Some pre-existing conditions can make certain drugs unsafe to take.

Contraindications for amphetamines include:

  • sensitivity to amphetamines or their derivatives
  • cardiovascular disease or arteriosclerosis, a thickening or hardening of artery walls
  • moderate to severe hypertension, or high blood pressure
  • a tendency to become agitated
  • a history of depression, bipolar disorder, motor or verbal tics, or Tourette's syndrome
  • thinking about or attempting suicide
  • glaucoma
  • overactive thyroid, known as hyperthyroidism
  • use of monoamine oxidase inhibitors (MAOIs) within the past 2 weeks, including moclobemide and toloxatone

Children and teenagers who have a heart problem may be at risk of sudden death if they use amphetamines.

People with a history of drug abuse or addiction should not use amphetamines.

Anyone who is taking supplements should make sure their doctor knows about this, if they may be prescribed amphetamines. The herbal supplement, St. John's wort, and the nutritional supplement glutamic acid (L-glutamine) can interact with amphetamines.