Drug withdrawal

Drug withdrawal, drug withdrawal syndrome, or substance withdrawal syndrome^[1] is the group of symptoms that occur upon the abrupt discontinuation or decrease in the intake of pharmaceutical 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 rather 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.

The route of administration, whether intravenous, intramuscular, oral, or otherwise can also play a role in determining the severity of withdrawal symptoms.^{[citation needed]} There are different stages of withdrawal as well; generally, a person will start to feel bad (crash or come down), progress to feeling worse, hit a plateau, and then the symptoms begin to dissipate. However, withdrawal from certain drugs (barbiturates, benzodiazepines, alcohol, glucocorticoids) can be fatal.^[2][3] While it is seldom fatal to the user, withdrawal from opiates (and some other drugs) can cause miscarriage, due to fetal withdrawal. The term "cold turkey" is used to describe the sudden cessation of use of a substance and the ensuing physiologic manifestations.

The symptoms from withdrawal may be even more dramatic when the drug has masked prolonged malnutrition, disease, chronic pain, infections (common in intravenous drug use), or sleep deprivation, conditions that drug abusers often develop as a secondary consequence of the drug. When the drug is removed, these conditions may resurface and be confused with withdrawal symptoms. Genes that encode for the alpha5 nicotinic acetylcholine receptor affect nicotine and alcohol withdrawal symptoms.