What is adverse drug reactions

Adverse drug reactions generally refers to the normal usage, the amount of the cases, or harmful to the human body in responding to accidents. However, arising from improper use of the reaction, such as using the wrong drugs and doses, drug abuse, suicide, such as over-medication are not included. World Health Organization Adverse Drug Reaction on a broad definition as: "for the prevention, diagnosis or treatment of diseases, or for the improvement of physiological function and taking the appropriate dose caused by the harmful, unintended or unwanted response to treatment."

Adverse drug reactions, including side effects, toxicity, allergic reactions, especially the role of heterogeneous reactions and teratogenesis.
1, side-effects: the more common side effects of drugs means the use of therapeutic doses of drugs, with the emergence of the disease and treatment purposes unrelated to the other and the role of inevitable. A drug often has a variety of roles, when people use one role, the role of the rest will be referred to as side-effects. Therapeutic effects of drugs and side effects of drug itself has pharmacological properties, they are relative, with the aim of treatment change. For example, ephedrine has excited the central nervous system and contraction of blood vessels, or the role of hypertension, such as for the treatment of low blood pressure, then the excitement caused by the central nervous system side effects is insomnia; the other hand, if the spirit for the treatment of depressive illness, then the blood pressure or is the side-effects of a high.
2, toxic reactions: drug toxicity refers to the body caused by more serious disorders and even the pathological changes of organs of a more serious side effects. In addition to individual body mass is particularly sensitive, the most toxic response was due to excessive use of pharmaceutical or drug use caused by too much time, the degree of its severity and the medication dose is closely related to the length of time. Even in the commonly used doses, some patients appear for various reasons toxicity. Such as liver and kidney is the body of drug metabolism and excretion of the most important organs, when their function is impaired, the drug can not be normal metabolism and excretion, it is easy to savings in the body, causing poisoning.
3, allergic reactions: allergic reactions, also known as allergic, idiosyncratic means of the use of certain drugs in patients with adverse reactions such as itching, various types of skin rashes, urticaria and anaphylactic shock. The occurrence of allergic reactions and pharmacological nature of the drug itself has nothing to do with the drugs is also not directly related to dose. For most people, even if the toxic dose of an allergic reaction will not occur, and patients with specific physical, when in the use of a very small dose can occur if there is contact with people who only penicillin solution will cause severe allergic reactions. Only as a result of allergic reactions occurred in patients with specific physical, the incidence rate is not high, but sometimes the consequences could be serious, even fatal, should be sufficient attention.
4, Special heterogeneous reaction: a very small number of people refer to the application of some medicine and pharmacological effects resulting from the reaction of no relevance. This special feature of heterogeneous reaction of congenital, often hereditary enzyme defects exist, normal non-performance in the application only after the incidence of certain drugs. Such as glucose -6 - phosphate dehydrogenase deficiency patients, the application of certain oxidizing drugs can lead to hemolysis.
5, Teratogenic Effects: Pregnancy refers to pregnant women taking on the embryo or fetus after the adverse reaction, the reaction caused by a very large extent, depend on the medication at the time of pregnancy stages of pregnancy. Gestation period of the previous three months, the impact of drugs on the fetus's largest, easily lead to fetal