Drug dependence

Drug dependence may occur when a person continues to use drugs— legal or illegal—even though their drug use causes them significant problems. 

It is regarded by many as a medical condition or a disorder not directly under the control of the individual. The term 'addict', with its negative implications, is not used any longer.

In general, drug dependence may be diagnosed if a person:

  • spends a significant amount of time obtaining the drug, using it, and/or recovering from its effects
  • develops a tolerance to the drug (see below)
  • continues using the drug even though they know it is causing them psychological and/or physical harm
  • wants to cut down or control their drug use (and perhaps makes repeated unsuccessful attempts to do so)
  • takes more of the substance, or uses it for longer, than they intend
  • reduces, or gives up entirely, important social, recreational and/or work activities because of their drug use
  • suffers symptoms of withdrawal when they stop using the drug (see below).

Three or more of these symptoms is generally considered sufficient for a diagnosis.


After using a drug for a while, a person may find that:

they need to take more of the drug to get an effect that they previously got with less, or
the drug simply becomes less effective in producing the desired effect.

This is called tolerance.


When a person who has been using a drug stops taking it, or reduces the dose, they may experience a physical and/or psychological reaction. This is called withdrawal. Because the dependent person has become tolerant to the drug's effects, they have been taking the drug just to feel normal. When they stop taking the drug, they may experience the opposite to the highs the drug originally gave them.

Withdrawal can be very unpleasant, producing symptoms such as tremors, sweating and vomiting, as well as extreme craving. For some drugs and some individuals, medical supervision during withdrawal is necessary.

The strength of the withdrawal varies, depending on:

  • the individual person
  • the drug they have been using
  • how much they have been taking
  • how long they have been taking it.

Bad withdrawal symptoms can make it very difficult for a user to stop or reduce their drug intake.


Detoxification is the term that used to be applied to withdrawal management. The process by which the body is purged of the drug and its immediate physical and psychological effects is called detoxification. Detoxification usually leads to some level of withdrawal, and medical assistance may be required. Anti-anxiety drugs such as benzodiazepines are sometimes prescribed for a short time during medically-supervised withdrawal.