ICD-9 : 995.2 • ICD : 10 : T88.7
- Adverse cutaneous drug reactions (ACDRs) are common in hospitalized (2–3%) as well as in ambulatory patients (>1%).
- Most reactions are mild, accompanied by pruritus, and resolve promptly after the offending drug is discontinued.
- Severe, life-threatening ACDRs do occur and are unpredictable.
- Drug eruptions can mimic virtually all the morphologic expressions in dermatology and must be the first consideration in the differential diagnosis of a suddenly appearing eruption.
- Drug eruptions are caused by immunologic or nonimmunologic mechanisms and are provoked by systemic or topical administration of a drug.
- The majority are based on a hypersensitivity mechanism and are thus immunologic and may be of types I, II, III, or IV.
Immunologically Mediated ACDR
See Table 22-1. It should be noted, however, that classification of immunologically mediated ACDR according to the Gell and Coombs classification is an oversimplification because in most reactions both cellular and humoral immune reactions are involved. Nonimmunologic reactions are summarized in Table 22-2.
Table 22-1 Immunologically Mediated Adverse Cutaneous Drug Reactions* |Favorite Table|Download (.pdf)
Table 22-1 Immunologically Mediated Adverse Cutaneous Drug Reactions*
Type of Reaction
Examples of Causative Drug
IgE-mediated; immediate-type immunologic reactions
Penicillin, other antibiotics
Urticaria/angioedema of skin/mucosa, edema of other organs, and anaphylactic shock
Drug + cytotoxic antibodies cause lysis of cells such as platelets or leukocytes
Penicillin, sulfonamides, quinidine, isoniazid
Petechiae due to thrombocytopenic purpura, drug-induced pemphigus
IgG or IgM antibodies formed to drug; immune complexes deposited in small vessels activate complement and recruitment of granulocytes
Immunoglobulins, antibiotics, rituximab, infliximab
Vasculitis, urticaria, serum sickness
Cell-mediated immune reaction; sensitized lymphocytes react with drug, liberating cytokines, which trigger cutaneous inflammatory response Contact sensitivity†
Sulfamethoxazole, anticonvulsants, allopurinol
Morbilliform exanthematous reactions, fixed drug eruption, lichenoid eruptions, Stevens-Johnson syndrome, toxic epidermal necrolysis
Table 22-2 Nonimmunologic Drug Eruptions |Favorite Table|Download (.pdf)
Table 22-2 Nonimmunologic Drug Eruptions
Reactions due to hereditary enzyme deficiencies
Individual idiosyncrasy to a topical or systemic drug
Mechanisms not yet known
Reactions are dose dependent, based on the total amount of drug ingested: pigmentation due to gold, amiodarone, or minocycline
Reactions due to combination of a drug with ultraviolet irradiation (photosensitivity)
Reactions have a toxic pathogenesis but can also be immunologic in nature (see Section 10)
Irritancy/toxicity of a topically applied drug
Atrophy by topically applied drug
Guidelines for Assessment of Possible ACDRs
- Exclude alternative causes, especially infections, in that many infections (especially viral) are difficult to distinguish clinically from the adverse effects of drugs used to treat infections.
- Examine interval between introduction of a ...