What are the effects of speed?

Amphetamine, also known as speed, sulphate, sulph, or whiz, is a stimulant drug
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Remember: All drugs, including the misuse of prescribed medication, can pose serious health risks, up to and including possible death.

Amphetamine sulphate, also known as speed, is a drug that usually comes in powder or tablet form. It may be taken by mouth, dissolved in water, injected, sniffed up the nose, or smoked.

There are three different types of amphetamines (the common brand names are in brackets):

  • Laevo or dl-amphetamine (Benzedrine)
  • dextroamphetamine (Dexedrine)
  • Methylamphetamine (Methedrine), also known as crystal meth and is the most potent of the three.

The short term effects of amphetamines

The effects of amphetamines tend to set in about 30 minutes after taking the drug.

Amphetamine is a stimulant, also known as an ‘upper’. It quickens the heartbeat, and users may experience increased confidence, sociability and energy levels.

Sometimes users feel anxious and restless and may panic and feel everyone is getting at them. Large amounts can cause panic, paranoia and hallucinations. Some people experience amphetamine psychosis, when they lose touch with reality.

Some other common effects of amphetamines include:

  • Raised blood pressure
  • A tense jaw and teeth grinding
  • Sweating and headaches
  • As it wears off people may feel very tired and depressed
  • Feelings of irritability, anxiety, restlessness, dizziness, depression and tremors
  • Insomnia is very common and can keep users awake for days afterwards 

The comedown from amphetamines

The comedown can last for a couple of days, leaving users feeling tired, depressed, irritable and physically uncomfortable.


It is possible to overdose on amphetamines, which can be incredibly dangerous.

The long term effects of taking amphetamines

Taking amphetamines can have a number of effects on the body.

Damage to heart health

Amphetamines can damage heart health due to the effects that speed has on your heart, including increased blood pressure. There is a risk of heart failure when taking amphetamines.

Increased blood pressure can also rupture or block tiny blood vessels. If this happens in the brain, it can lead to paralysis or coma.

Risks of injecting amphetamines

Injecting can damage veins and lead to gangrene. Injection also puts users at risk of dangerous infections such as Hepatitis and HIV, from contaminated needles, syringes and other equipment.

Sleep problems, weight loss, and the immune system

Disruption of sleep and eating patterns may lead to weight loss and becoming very physically run down with regular use. This can reduce resistance to illnesses like colds and flus because your immune system is not working at its best.

Mental health

Heavy, regular users may become very depressed, anxious, and paranoid. Taken over a period of time, this can cause psychotic mental illness to develop. Those with an existing underlying mental health condition may find that amphetamines trigger their condition.

Taking amphetamines can also make a person become more aggressive over time and they may experience mood swings.


Amphetamine is addictive, both physically and psychologically. Those who are addicted to amphetamines not only crave the drug physically, but they might also find they are dependent on it to cope mentally and may not be able to imagine their life without it.

If you think you might be dependent on drugs, there are a number of services that can help. Find a service near you here or contact the Drugs Helpline on 1800 459 459 to find out about options in your area.

How to help someone who has taken amphetamines

If there’s an emergency and you are trying to help someone who has taken amphetamines, here are some things to try:

  • Calm the person down and reassure them that everything is alright
  • Talk quietly and explain that the panicky feeling will gradually go
  • Keep them away from loud noises and bright lights
  • Encourage them to breathe slowly and deeply to prevent hyperventilation

Learn more about helping a friend in a drug emergency here.

Amphetamines and the law

The Misuse of Drugs Acts controls most of the amphetamine type drugs. Their unauthorised production, supply or possession is an offence, as is allowing premises to be used for producing or supplying the drugs.

Reducing harm when taking drugs

If you choose to take drugs, remember:

  • Start with a very small test dose and wait at least two hours before taking more.
  • Stay with your friends and do not leave anybody who is intoxicated on their own.
  • Avoid mixing drugs and alcohol. Every time you mix drugs, including alcohol and prescription medication, you increase the risks.
  • Always hydrate with water but don’t drink over a pint an hour.
  • If you are dancing, remember to take breaks from dancing and give yourself time to cool down.
  • Don’t be afraid to get help if you or a friend become unwell or feel suicidal after using drugs. Call 112 or 999.

Supports and Services

  • Drugs.ie: Online information and support for drug and alcohol use. Includes a national directory of drug and alcohol services
  • HSE Drugs, Alcohol, HIV and Sexual Health Helpline: Freephone 1800 459 459.
  • The Club Drug Clinic offers advice, support and detoxification for GHB (Liquid Ecstasy, G) and other chemsex and club drugs is an integrated person centred specialist addiction service: Tel 016488600
  • Rialto Community Drug Team
  • Find a local service through the National Directory for Drug and Alcohol Services at Drugs.ie
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