Module 6: how drugs work: facilitator's guide

8.2 Tolerance

Page last updated: 2004


Question - What is your understanding of the term 'tolerance' in relation to AOD issues?

Answer - Tolerance occurs when a regular user of a drug gradually becomes less responsive to the drug. This can often lead to the person taking larger amounts of the drug to achieve the same effect.

Tolerance develops via two main mechanisms:
  1. The liver increases the level of enzymes to metabolise the drug, so it becomes more effective at eliminating the drug.
  2. The brain's receptors respond to the regular presence of the drug by becoming less sensitive to the drug's effects.
A new user of a drug has no tolerance to it, and will be affected more than an experienced user. For example while a young person who has never consumed alcohol may become quite intoxicated from having one standard drink, another person of the same age and gender may require three or more drinks to experience the same effect.

Question - Is the concept of tolerance relevant to young people. If so, how?

Answer - Many young people will have little tolerance to drugs and alcohol. However, young people will become tolerant to most drugs with regular use. Tolerance can develop rapidly with regular use of some drugs including amphetamines, ecstasy, heroin and benzodiazepines. Other drugs such as nicotine do not appear to demonstrate tolerance, except for the initial effects for na´ve users such as nausea and headache.

Case study - John

John is a 17-year-old young man who was arrested for theft and was sent to a juvenile correctional facility. At the time of his arrest, he was using two to three $50 shots of heroin per day, and his tolerance to heroin was quite high.

John spent three months in the juvenile facility, during which time he did not use heroin. He ingested rohypnol tablets on three occasions during his first week there, but since then, has not used any other drugs.

John was released from the juvenile facility, and went to the refuge accommodation that a social worker had arranged for him. He wasn't happy there and went out to find some of the friends he used to hang out with prior to his arrest.
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Question - What might happen to John if he used a $50 shot of heroin again that evening? Why?

Question - What factors might make a difference as to whether John experienced an overdose or not? (Hint: see Topic 6: Drug Effects).