Drug withdrawal, drug withdrawal syndrome, or substance withdrawal syndrome, is the group of symptoms that occur upon the abrupt discontinuation or decrease in the intake of meditational or recreational drugs. In order for the symptoms of withdrawal to occur, one must have first developed a form of drug dependence. This may occur as physical dependence, psychological dependence or both. Drug dependence develops from consuming one or more substances over a period of time.
Dependence arises in a dose-dependent manner and produces withdrawal symptoms that vary with the type of drug that is consumed. For example, prolonged use of an antidepressant medication is likely to cause a much different reaction when discontinued compared to discontinuation of an opioid, such as heroin. Withdrawal symptoms from opiates include anxiety, sweating, vomiting, and diarrhea. Alcohol withdrawal symptoms include irritability, fatigue, shaking, sweating, and nausea. Withdrawal from nicotine can cause irritability, fatigue, insomnia, headache, and difficulty concentrating. Many prescription and legal nonprescription substances can also cause withdrawal symptoms when individuals stop consuming them, even if they were taken as directed by a physician.