Unpleasant physical and mental symptoms that occur when a person stops using a drug or substance on which he or she is dependent (see DEPENDENCE). The symptoms include tremors, sweating, and vomiting; these are reversed if further doses are given. Alcohol and ‘hard’ drugs, such as morphine, heroin, and cocaine, are among the substances that induce dependence, and therefore withdrawal symptoms, when stopped. Amphetamines and nicotine are other such examples.