Classification of drug exanthema.
| Drug reaction (type) | Drug reaction description |
| Type A reaction | Toxic-pharmacological; dose-dependent and predictable. |
| Type B reaction | Allergic, pseudoallergic intolerance and idiosyncratic reactions, dose-independent |
| Type C reaction | Cumulative doses with long duration of use |
| Type D reaction | Carcinogenic (causing cancer), teratogenic (effects that can cause malformations in the unborn child) reactions; late-onset, dose-independent |
| Type E reaction | due to drug withdrawal |
| Type F reaction | Due to insufficient therapeutic effect |
