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. 2001 Mar;51(3):209–212. doi: 10.1046/j.1365-2125.2001.00355.x

Table 1.

Principal classes of adverse drug reactions [1]

Type A Reactions that are predictable from the known primary or secondary pharmacology of the drug
Type B Reactions that are not predictable from the known pharmacology of the drug
Type C Reactions whose characteristics can be predicted or rationalized from the chemical structure of the drug
Type D Carcinogenic or teratogenic reactions