In adverse drug reactions involving overdoses, the toxic effect is simply an extension of the pharmacological effect (Type A adverse drug reactions). On the other hand, clinical symptoms of<unk> s (Type B adverse drug reactions) are different from the pharmacological effect of the drug. The proposed mechanism of most<unk> s is immune-mediated toxicity. To create an immune response, a foreign molecule must be present that antibodies can bind to (i.e. the antigen) and cellular damage must exist. Very often, drugs will not be immunogenic because they are too small to induce immune response. However, a drug can cause an immune response if the drug binds a larger molecule. Some unaltered drugs, such as penicillin, will bind avidly to proteins. Others must be bioactivated into a toxic compound that will in turn bind to proteins. The second criterion of cellular damage can come either from a toxic drug/drug metabolite, or from an injury or infection. These will sensitize the immune system to the drug and cause a response.<unk>  reactions fall conventionally under toxicology.
Idiosyncratic drug reaction
Bullous drug reaction
Fixed drug reaction
Anticonvulsant hypersensitivity syndrome
Adverse drug reaction
Aerotoxic syndrome
Drug interaction
Allopurinol hypersensitivity syndrome