Physical dependence describes a condition that occurs after prolonged use of a drug in which an individual suffers from negative symptoms if he abruptly stops using or decreases the dosage of the drug. Physical dependence is also characterized by drug tolerance, in which an individual's response to a drug decreases. Different drugs may cause different symptoms of dependence and may also be characterized by different withdrawal symptoms. Both recreational drugs, such as alcohol and heroin, and prescription drugs, such as propranolol and morphine, are capable of causing dependence. The symptoms of dependence, which primarily appear during withdrawal, may be physical or psychological in nature.
There are many factors that may contribute to the development of a harmful physical dependence on a substance. Some families, for example, seem to have a genetic propensity for addiction and dependence while others can start and stop using a drug at will. Age can also be a substantial factor; one who begins using a drug early in life is likely to have problems with physical dependence later. There are also many psychological and cultural influences that can lead to dependence. Many people abuse and become dependent on alcohol, for instance, because they seek an escape from some of the unpleasant conditions of their lives.
The symptoms associated with physical dependence, particularly during withdrawal after one suddenly stops using a drug, vary significantly based on the person and on the drug. Sweating, increased blood pressure and increased heart rate are associated with most forms of withdrawal. More substantial symptoms such as hallucinations and seizures are also possible. Some severe withdrawals, as after prolonged alcoholism, can lead to convulsions or other painful symptoms that may even be fatal. These symptoms tend to be accompanied by an intense craving for the drug in question; indulging that craving often alleviates the withdrawal symptoms but does nothing to free one from the physical dependence.
There are a variety of treatment and therapy options available to help people overcome physical dependence. In some cases, a different drug that mitigates some of the withdrawal symptoms is taken when an individual stops using the substance on which he is dependent. This is particularly common when the effects of withdrawal can be harmful or deadly. In other cases, an individual slowly reduces the dose that he takes of the drug on which he has a physical dependence. Both of these options are commonly done in an isolated, therapeutic rehabilitation setting where one can deal with substance abuse problems in a controlled setting with plenty of help and support.