IGCSE Biology glossary
Drug dependence
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Definition
The condition where a person's body has adapted to the presence of a drug and cannot function normally without it. If the drug is withdrawn, the person experiences unpleasant withdrawal symptoms such as headaches, nausea, anxiety or tremors.
What to include in an exam answer
Dependence can be physical (body needs the drug) or psychological (mind craves the drug). Always link it to withdrawal symptoms when the drug is stopped.
Example in context
Explain the difference between tolerance and dependence (2 marks): Tolerance is needing a larger dose to achieve the same effect. Dependence is when the body cannot function normally without the drug and stopping causes withdrawal symptoms.
Related syllabus topic
Drugs