Ice Breaker

Ice will cause psychosis in all people

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Ice and the brain

Ice (crystal methamphetamine) triggers the release of three chemicals in the brain, called dopamine, noradrenaline and serotonin. These chemicals are also released during pleasant activities - like eating and sex – and they are responsible for making us feel alert and excited. But flooding the brain with these chemicals can cause an 'overload' in the system which is why some people can’t sleep for days or experience symptoms of psychosis after taking ice.

Ice also stops the brain from reabsorbing these chemicals which lowers their supply in the brain. This is why people often feel low or irritable for 2-3 days after taking ice.

Over the long term, regular use of ice can damage or destroy dopamine receptors in the brain — sometimes to a point where the person using the drug no longer feels normal without having ice in their system. Even after people have stopped using ice it can take up to a year before these brain changes return to normal.

What are the effects of ice?

The initial effects of ice often last for between 4 and 12 hours depending on how much ice is consumed. Although the effects of ice are usually felt quickly (within minutes if it is smoked or injected, or about 30 minutes if snorted or swallowed), it can take 1 to 2 days to entirely leave the body.

The physical effects of ice can include:

  • Headaches and dizziness
  • Dilated (enlarged) pupils and blurred vision
  • Dry mouth
  • Jaw clenching, teeth grinding
  • Insomnia
  • Increased attention, alertness and talkativeness
  • Trembling
  • Sweaty, cold and clammy skin
  • Increased breathing and body temperature
  • Increased heart rate and blood pressure
  • Reduced appetite
  • Stomach cramps, nausea and vomiting
  • Dehydration
  • Aggressive behaviour
  • Increased energy
  • Changes in libido
  • Stroke
  • Dental problems: increased tooth sensitivity, cracked teeth and cavities, gum disease
  • Dependence
  • Poor concentration and memory
  • Increased risk of hepatitis C and HIV in people who inject ice
  • Heart and lung problems, chest pains
  • Kidney problems, including kidney failure
  • Malnutrition and weight loss
  • Exhaustion
  • Movement problems

Use of methamphetamines (including ice) is also associated with elevated mortality rates relating to overdose, natural diseases (such as coronary disease), suicide and accidental injury.

The ComeDown Phase and Withdrawal

A 'comedown' phase or ‘crash’ is often experienced by people who use ice as the drug starts to wear off. These feelings can last a few days and symptoms can include:

  • Feeling down or depressed
  • Decreased appetite
  • Exhaustion
  • Increased need for sleep
  • Irritability
  • Feeling anxious.

Withdrawals refer to unpleasant symptoms experienced by people with a dependence on ice. These symptoms can last for several days or many weeks, depending on the severity of use. Withdrawal symptoms can include:

  • Headaches
  • Anxiety
  • Aggression
  • Restlessness
  • Cramps
  • Vomiting.


Australian Drug Foundation. (2016). Amphetamines. Melbourne: State Government Victoria.

Australian Institute of Health and Welfare. (2018). Alcohol, tobacco & other drugs in Australia. Canberra: Australian Institute of Health and Welfare.

Darke S., Kaye S., McKetin R., Duflou J. (2008). The major physical and psychological harms of methamphetamine use. Drug Alcohol Rev 2008; 27: 253–62.

Darke, S., Kaye, S., and Duflou, J. (2017). Rates, characteristics and circumstances of methamphetamine-related death in Australia: a national 7-year study. Addiction.

McKetin, R., & Black, E. (2014). Methamphetamine: What you need to know about speed, ice, crystal, base and meth. Sydney: National Drug and Alcohol Research Centre, University of New South Wales.

See ‘The effects of ice on the brain’ fact sheet for sources related to cognitive effects.

Page last reviewed: Wednesday, 3 July 2019