Drug dependency. Abstract image of green pills emerging from a woman's head. The image depicts drug dependency, the compulsive desire to keep taking drugs. This may be to produce the desired effects of the drug or to prevent the ill-effects of withdrawal. Dependence can be psychological (producing cravings) or physical (producing withdrawal symptoms). The addictive drugs that this image could represent range from hallucinogen's, designer drugs, such as ecstasy, and sleeping pills. The image could also represent the use and abuse of other non-addictive nervous system drugs such as headache pills.