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Drug eruption general overview
Other Resources UpToDate PubMed

Drug eruption general overview

Contributors: Noah Craft MD, PhD, Lindy P. Fox MD, Lowell A. Goldsmith MD, MPH, Michael D. Tharp MD
Other Resources UpToDate PubMed


There are more than 80 specific cutaneous drug reaction patterns in the skin. Adverse cutaneous drug reactions are seen in 2%-3% of inpatients. This synopsis summarizes simple drug eruptions with minimal systemic involvement. Complex drug eruptions with systemic manifestations such as drug hypersensitivity syndrome, Stevens-Johnson syndrome, toxic epidermal necrolysis, and serum sickness-like reaction are discussed in greater detail elsewhere. Drug-induced eruptions should always be considered in the differential diagnosis of any patient on medication presenting with a sudden "rash," particularly in individuals who are on multiple medications or have recently started a new drug or drug preparation.

Drug eruptions are often of unknown etiology and mechanism but always constitute an adverse effect. They may be immunologic or nonimmunologic; not all drug eruptions imply allergy. Possible other causes include metabolic reaction, drug accumulation or overdosage, combined manifestation with a coexistent disease, or interactions with other medications. The most common morphologies seen are morbilliform (95%) and urticarial (5%). Pustular, bullous, and papulosquamous morphologies also occur but are less common. Drug reactions may cause pruritus without an obvious cutaneous manifestation. They occur more commonly in inpatients, the elderly, females, and the immunocompromised.

Drugs and classes of medications frequently reported to cause a simple exanthem include antibiotics (penicillins, cephalosporins, trimethoprim-sulfamethoxazole, quinolones, gentamicin), NSAIDs, angiotensin-converting enzyme (ACE) inhibitors, sulfonamides, anticonvulsants, allopurinol, thiazides, isoniazid, thalidomide, and nelfinavir.


L27.1 – Localized skin eruption due to drugs and medicaments taken internally

28926001 – Drug eruption

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Differential Diagnosis & Pitfalls

Specific drug eruption patterns include:
  • Exanthematous drug eruption
  • Fixed drug eruption
  • Erythroderma
  • Drug-induced pigmentation
  • Bullous drug eruption
  • Lichenoid drug eruption
  • Drug-induced nail pigment
  • Drug-induced non-palpable purpura
  • Drug-induced oral ulcer
  • Drug-induced photoallergic reaction
  • Drug-induced flagellate pigmentation
  • Drug-induced hypopigmentation
If lesions are painful and the patient appears ill or toxic, consider impending Erythema multiforme, Stevens-Johnson syndrome, or Toxic epidermal necrolysis.

Also consider:
  • Viral exanthem (Hand, foot, and mouth disease, Cytomegalovirus infection, Enteroviral infection, Adenovirus infection, Mononucleosis, Measles, Roseola, Parvovirus B19 infection, Human immunodeficiency virus primary infection)
  • Acute graft-versus-host disease
  • Cutaneous eruption of lymphocyte recovery
  • Bacterial infection (streptococcal, Acute meningococcemia, Rocky Mountain spotted fever)
  • Kawasaki disease
  • Porphyria cutanea tarda
  • Urticaria (eg, physical stimuli)
  • Acne vulgaris
  • Pityriasis rosea
  • Lichen planus
  • Contact dermatitis (Allergic contact dermatitis, Irritant contact dermatitis)
  • Acute febrile neutrophilic dermatosis (Sweet syndrome)
  • Scarlet fever
  • Secondary syphilis
  • Leukocytoclastic vasculitis

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Last Updated:02/04/2021
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Drug eruption general overview
A medical illustration showing key findings of Drug eruption general overview : Rash, Widespread distribution, Pruritus
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