In drug exanthema (synonyms: Drug-induced rash; Drug dermatitis due to ingested drug; Drug exanthema; Dermatitis due to drug; Dermatitis due to vaccination; Dermatitis due to medication; Dermatitis due to vaccine; Dermatitis due to ingested chemical; Dermatitis due to ingested drug; Dermatitis due to ingested substance; Eczema due to drug; Erythema due to drug; Generalized drug dermatitis due to ingested drug; Generalized drug erythema; Skin allergy due to drug; Localized drug dermatitis due to ingested drug; Localized rash due to drug; Localized rash due to vaccine; Localized erythema due to drug; Drug exanthema; Toxic exanthema due to drug; ICD-10-GM L27. -: Dermatitis due to orally, enterally, or parenterally ingested substances) is an acute skin manifestation following the use of a drug. This hypersensitivity reaction can be toxic, allergic, and pseudoallergic.
In allergic reactions to a drug (= drug allergy) or to their additives, type I, IIa, III and IV allergies play a role. In addition to allergic reactions, pseudoallergic reactions (pathological reaction to a noxious substance (pollutant) acting on the body, which resembles an allergy but is not based on an antigen-antibody reaction) can also occur. This is a direct IgE-independent release of histamine from mast cells in the case of antibiotics, muscle relaxants, and opioids, for example.
Drug exanthema is one of the most common intolerance reactions to drugs.
In adverse drug reactions, the skin is affected in up to 80% of cases.
The following forms of drug exanthema can be distinguished:
- Localized form
- Generalized form
The prevalence (frequency of illness) is about 1.4-3.0% of all emergency admissions for drug intolerance and about 15-30% of all hospitalized patients.
Course and prognosis: Skin symptoms usually appear between the 7th and 12th day after the first ingestion of a drug. With repeated ingestion of the triggering agent, the drug exanthema appears within 48 hours.After discontinuation of the triggering agent, the exanthema heals within a few days (maximum one week). If the hypersensitivity reaction is very severe, healing may take up to 6 weeks.
Independently of the skin symptoms, immunological reactions may also occur in the case of drug allergy, which are divided according to their course into: Immediate reactions (occurrence within one to six hours) with low-grade to life-threatening symptoms of anaphylaxis (strongest allergic reaction) and late reactions (occurrence several hours to several days after exposure). In the latter, in the form of exanthema (skin rash).
Notice: IgE-mediated reactions may disappear after about ten years, and the skin test then becomes negative. For example, patients with a purported history of penicillin allergy had allergies in only 1.7% of cases on allergy testing.
