Amphetamines (speed): what are the effects?

The effects of any drug (including amphetamines) vary from person to person. How amphetamines affect a person depends on many things including their size, weight and health, also whether the person is used to taking it. The effects of amphetamines, as with any drug, also depend on the amount taken.

There is no safe level of amphetamine use. Use of any drug always carries some risk—even medications can produce unwanted side effects. It is important to be careful when taking any type of drug.

Immediate effects

Depending on how amphetamines are taken, the effects may be felt immediately (through injecting or smoking) or within 30 minutes (if snorted or swallowed).

Low to moderate doses

  • feelings of euphoria, excitement and a sense of wellbeing
  • increased confidence and motivation
  • a sense of power and superiority over others
  • increased talkativeness
  • repetition of simple acts
  • nervousness, anxiety, agitation and panic
  • increased libido
  • paranoia
  • hallucinations
  • irritability, hostility and aggression
  • headaches
  • dizziness
  • feeling more awake and alert, reduced need for sleep and difficulty sleeping
  • abrupt shifts in thought and speech that can make people difficult to understand
  • enlarged (dilated) pupils
  • dry mouth
  • increased breathing rate
  • shortness of breath (from smoking it)
  • increased heart rate and blood pressure
  • irregular heart beat, palpitations
  • chest pain
  • reduced appetite
  • stomach cramps
  • stomach irritation (if swallowed)
  • feeling more energetic
  • increased sweating
  • increased body temperature
  • faster reaction times
  • feelings of increased strength
  • itching, picking and scratching.

Higher doses

A high dose of amphetamines can cause a person to overdose. This means that a person has taken more amphetamines than their body can cope with. Not knowing the strength or purity of amphetamines increases the risk of overdose. Injecting runs a greater risk of overdose due to large amounts of the drug entering the blood stream and quickly travelling to the brain.

The effects of a high dose of amphetamines can intensify some of the effects listed in the diagram. People may also experience:

  • blurred vision
  • tremors
  • irregular breathing
  • loss of coordination
  • collapse
  • rapid pounding heart
  • violent or aggressive behaviour
  • hallucinations
  • seizures
  • stroke
  • coma.

High doses and frequent heavy use can also create an “amphetamine psychosis”, characterised by paranoid delusions, hallucinations and bizarre, aggressive or violent behaviour. These symptoms usually disappear a few days after the person stops using amphetamines.

Coming down

As the effects of amphetamines begin to wear off, a person may experience a range of effects. These effects can last for several days after use and may include:

  • feeling restless, irritable and anxious
  • aggression, that may lead to violence
  • tension
  • radical mood swings
  • depression
  • paranoia
  • lethargy
  • total exhaustion.

Long-term effects

Some of the long-term effects of amphetamine use include:

  • malnutrition and rapid weight loss due to reduced appetite
  • chronic sleeping problems
  • reduced immunity and increased susceptibility to infections due to not sleeping or eating properly
  • cracked teeth and other dental problems from clenching the jaw, grinding the teeth, dry mouth and poor hygiene
  • high blood pressure and rapid and irregular heartbeat which place stress on the heart and can increase the risk of heart-related complications such as heart attack and heart failure
  • increased strain on the kidneys which can result in kidney failure
  • increased risk of stroke
  • depression, anxiety and tension
  • paranoia
  • violence
  • panic and confusion
  • muscle rigidity
  • breathlessness
  • damage to the heart muscle
  • psychological problems such as poor memory and concentration.

Other effects of amphetamine use

Taking amphetamines with other drugs

The effects of mixing amphetamines with other drugs, including alcohol, prescription medications and over-the-counter medicines, are often unpredictable.

Mixing amphetamines with other stimulant drugs (such as cocaine or ecstasy) increases the stimulant effects and places enormous pressure on the heart and body, which can lead to stroke.

Combining amphetamines with depressant drugs such as alcohol, cannabis, heroin or benzodiazepines also places the body under great stress.

For more information, please click on the Australian Drug Foundation's DrugInfo Clearinghouse web site link below.
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