Tolerance and dependence

CigarettesThe more often a drug is used, the more accustomed the brain becomes to its effects. This is called neuroadaption. The common effect of neuroadaption is an increased tolerance to the drug.

A person can be said to have developed a tolerance to a drug when:
  • the same dose of the drug no longer produces the effect that it used to
  • increased doses of the drug are needed to get the same effect
Tolerance becomes known as dependence when not having the drug begins to produce a negative response: the user needs to take the drug to feel ‘normal’ rather than to get the effect they first began taking the drug for.