•  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 physical 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.

In the short-term, methamphetamine use can result in an increased heart rate and blood pressure, and feelings of irritability, restlessness, paranoia and anxiety. In some cases, it can also lead to aggressive or violent behaviour.

Over a longer period of time, methamphetamine use can cause weight loss and malnutrition (due to reduced appetite and poor diet), mood swings and depression (see FAQ what are the mental health risks of methamphetamine use?), weakened immune system, skin and dental problems, and social problems.

Other serious medical problems that can arise from methamphetamine use include stroke, heart attack, seizures, kidney and liver damage, and fatal or non-fatal overdose.

People who inject methamphetamine may also experience harms such as infections, thrombosis, endocarditis and increased risk of blood-borne viruses such as hepatitis if they engage in unsafe injecting practices.

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