Methamphetamine use stimulates the brain and central nervous system, and can result in a variety of adverse outcomes. The effect that methamphetamine has on an individual depends on a number of factors. These include:

In 2022 there were 516 overdose deaths in Australia which involved amphetamine-type stimulants, of which the majority (72%) occurred among men. Most of these deaths (90%) were unintentional. 

The vast majority (97%) of drug-induced deaths are due to overdose, however a small number of methamphetamine-related deaths may be excluded from the above figure (e.g., due to natural disease, homicide, etc). 

In 2022-23 there were 13,906 hospital separations due to the use of stimulants^†.

In 2022-23, Australian men accounted for more hospital separations due to the use of stimulants^† than women.

In 2022-23, the largest proportion of hospital separations due to the use of stimulants^† occurred among 30-39 year olds (36%).

In 2022-23, Australians were more likely to be hospitalised for mental and behavioural disorders due to the use of stimulants^† (92%, n=12,838) than for poisonings by psychostimulants^† (8%, n=1,068).

Methamphetamine use stimulates the brain and central nervous system, and can result in a variety of adverse outcomes. The effect that methamphetamine has on an individual depends on a number of factors. These include:

• how much methamphetamine is taken
• the method of use
• the form and purity of the methamphetamine
• the height and weight of the user
• the user’s current physical and mental health status
• the user’s previous experience with methamphetamine (i.e. new user vs frequent user)
• whether other substances (alcohol, tobacco, medications, or other illicit drugs) are used at the same time as methamphetamine.

There are a variety of mental health risks associated with methamphetamine use. Many of these risks are very serious, and can result in severe short- and long-term consequences for the user.

The effects of methamphetamine are the same regardless of which form (e.g. powder/base/crystal) is used. However, crystal methamphetamine (ice) tends to be more potent and purer than other forms, and is also more likely to be smoked or injected. As a result, the effects of ice are both more likely to occur and likely to be more intense than when other forms of methamphetamine are used.

People who regularly use methamphetamine may experience a range of negative impacts on their mental health, including:

• depression and anxiety
• agitation and mood swings
• violence and aggression
• impaired cognitive function, concentration, and lack of motivation.

There is a strong association between methamphetamine use and psychosis. Methamphetamine use can cause psychotic symptoms in otherwise healthy people, and can also trigger or exacerbate psychosis in people who have pre-existing mental health conditions.

Regular use of methamphetamine may also lead to dependence (addiction). Dependent users develop a tolerance to methamphetamine, and need to take larger doses of the drug to achieve the same effect and feel ‘normal’. The urge to use methamphetamine can become more important than other activities in their lives, resulting in poor physical and mental health, social and financial problems, and family and social breakdown. See FAQ What are the diagnostic criteria for methamphetamine-related mental health disorders?

For more information about the effects of methamphetamine, see FAQs What are the short-term effects of methamphetamine use? and What are the physical health risks of methamphetamine use?

The reference guide used by clinicians to diagnose mental health disorders is known as the Diagnostic and Statistical Manual of Mental Disorders (DSM). The most recent version of the manual is the Diagnostic and Statistical Manual of Mental Disorders – 5th Edition (DSM-5).

DSM-5 Diagnostic Criteria for Stimulant Use Disorder

A stimulant use disorder is defined as a pattern of amphetamine-type substance, cocaine, or other stimulant use leading to clinically significant impairment or distress, as manifested by at least two of the following, occurring within a 12-month period:

1.    The stimulant is often taken in larger amounts or over a longer period than was intended

2.    There is a persistent desire or unsuccessful efforts to cut down or control stimulant use

3.    A great deal of time is spent in activities necessary to obtain the stimulant, use the stimulant, or recover from its effects

4.    Craving, or a strong desire or urge to use the stimulant

5.    Recurrent stimulant use resulting in a failure to fulfil major role obligations at work, school, or home

6.    Continued stimulant use despite having persistent or recurrent social or interpersonal problems caused or exacerbated by the effects of the stimulant

7.    Important social, occupational, or recreational activities are given up or reduced because of stimulant use

8.    Recurrent stimulant use in situations in which it is physically hazardous

9.    Stimulant use is continued despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by the stimulant

10.  Tolerance, as defined by either of the following:

a.    A need for markedly increased amounts of the stimulant to achieve intoxication or desired effect.

b.    A markedly diminished effect with continued use of the same amount of the stimulant.

Note: This criterion is not considered to be met for those taking stimulant medications solely under appropriate medical supervision, such as medications for attention-deficit/hyperactivity disorder or narcolepsy.

11.  Withdrawal, as manifested by either of the following:

a.    The characteristic withdrawal syndrome for the stimulant (refer to Criteria A and B of the criteria set for stimulant withdrawal, p. 569).

b.    The stimulant (or a closely related substance) is taken to relieve or avoid withdrawal symptoms.

Note: This criterion is not considered to be met for those taking stimulant medications solely under appropriate medical supervision, such as medications for attention-deficit/hyperactivity disorder or narcolepsy.

A mild stimulant use disorder is defined as the presence of 2-3 of the above symptoms.

A moderate stimulant use disorder is defined as the presence of 4-5 of the above symptoms.

A severe stimulant use disorder is defined as the presence of 6 or more of the above symptoms.

Australians who used methamphetamine or amphetamine^† in the past 12 months were significantly more likely to have been diagnosed with or treated for a mental illness (44%) than those who had not used meth/amphetamine in the past 12 months (18%).

Australians who used methamphetamine or amphetamine^† in the past 12 months were significantly more likely to report high or very high levels of psychological distress compared to those who did not use methamphetamine or amphetamine in the past 12 months.