While there is valid concern about the potential for methamphetamine tolerance and dependence among users, it is important to note that some people who try methamphetamine once or twice do not necessarily develop a problem. However, many people find it difficult to keep their distance from the drug once they’ve experienced its effects.

The risk of harm is only partly related to the nature of the drug itself. Other important factors include the nature of the person using the drug and the context in which the drug is used. For example, a young person who is struggling with mental health issues such as depression and/or having trouble at school, has an increased risk for developing a problem with any substance, including methamphetamine. When a person experiences feelings of inadequacy or hurt, the risk of depending on a drug to make one “feel good” is increased.

Drugs like methamphetamine may provide initial relief, but very quickly users can find themselves needing larger quantities of the drug in order to re-experience their initial euphoria. This is called tolerance and occurs because the brain learns to adapt to the drug’s presence and begins to block its effect on mood. With tolerance comes the risk of dependence, the need to repeatedly use a substance in order to feel normal and function properly.

People who use methamphetamine also take risks simply by using a drug that is unregulated and sold on the street. Methamphetamine is often produced by people who lack the necessary skills and knowledge, so much of what is sold contains unwelcome contaminants.

People often add to their problems by mixing substances. When methamphetamine is mixed with alcohol, cannabis, cocaine, or other substances, the effects of each substance is altered, and the result may be very dangerous. Additionally, methamphetamine can have a negative impact on the effectiveness of prescription drugs such as HIV medication.

People who repeatedly consume high doses tend to lose interest in their hygiene and appearance. They may develop tooth and gum problems (called “meth mouth”) or skin sores resulting from scratching the areas in which they inject the drug. Or they may sever ties with family members, friends, and others who do not support their drug use. They may steal or commit other crimes in order to buy drugs. They may ignore responsibilities that once gave them a sense of pride, or give up on hobbies that gave them pleasure. They may even let go of long-held dreams that provided them with a sense of purpose and meaning.

Methamphetamine use is particularly harmful when a person is:

• masking a mental illness – methamphetamine can hide or worsen a person’s mental illness. Research suggests that people suffering from mental issues are most likely to have co-existing substance use problems.
• bingeing – some users take excessive amounts of methamphetamine over a short or limited period of time, such as an evening or weekend. Bingeing may also lead a person to make poor decisions (ignoring important responsibilities, missing school or work, engaging in high-risk sex, forgetting to eat or sleep).
• using needles – people who inject methamphetamine are more likely to become dependent. They are also more likely to contract or spread blood-borne diseases, such as HIV/AIDS or Hepatitis C, through the sharing of needles.
• having high-risk sex – people who use methamphetamine are more likely to take sexual risks, such as not using condoms or engaging in other high-risk sexual behaviour. As a result, they have higher rates of sexually transmitted diseases than other groups.
• long-term heavy use – people who use medium to high doses of methamphetamine for a long time can develop a lifestyle that includes failure to take care of personal hygiene or provide the body with adequate food, water, and sleep. This, combined with the drug’s impact on mental processes, can lead to significant brain and organ damage. Symptoms of long-term use include:
  • schizophrenia-like behaviour including auditory and visual hallucinations
  • repetitive behaviour patterns (e.g., picking at skin, or pulling at hair)
  • formication (delusions of parasites or insects on skin)
  • paranoid delusions leading to sudden aggressive behaviour
  • psychosis resulting in homicidal or suicidal thoughts