Adverse effects of systemic therapy can also be observed on the skin. Pharmacological (predictable) and idiosyncratic (unpredictable) responses are distinguished. Drug allergy is also included here, most often type IV (e.g., toxic epidermal necrolysis). The temporal relationship between an reaction and drug intake is important for establishing the diagnosis; laboratory tests and in-vivo exposure tests are used for confirmation.
Treatment measures primarily include discontinuing the suspected medication, topical dermatological teratment and, in more severe cases, systemic therapy can be provided (antihistamines, corticoids, and/or immunosuppressants, IVIG, biologicals). An entry in the patien's medical is important.