<unk> ,<unk>  syndrome, or substance withdrawal syndrome, is the group of symptoms that occur upon the abrupt discontinuation or decrease in the intake of pharmaceutical or recreational<unk> s. In order for the symptoms of withdrawal to occur, one must have first developed a form of<unk>  dependence. This may occur as physical dependence, psychological dependence or both.<unk>  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<unk>  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. 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<unk> s (barbiturates, benzodiazepines, alcohol, glucocorticoids) can be fatal. While it is seldom fatal to the user, withdrawal from opiates (and some other<unk> s) can cause miscarriage, due to fetal withdrawal. The term "cold turkey" is used to describe the sudden cessation use of a substance and the ensuing physiologic manifestations. The symptoms from withdrawal may be even more dramatic when the<unk>  has masked prolonged malnutrition, disease, chronic pain, infections (common in intravenous<unk>  use), or sleep deprivation, conditions that<unk>  abusers often suffer as a secondary consequence of the<unk> . When the<unk>  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.
Drug withdrawal
Nicotine withdrawal
Opioid withdrawal
Alcohol withdrawal syndrome
Benzodiazepine withdrawal syndrome
Antidepressant discontinuation syndrome
Benzodiazepine dependence
Alcohol intoxication