Serum sickness
Serum sickness is the prototypic type III (immune-complex) hypersensitivity, occurring about 1 to 2 weeks after exposure to a foreign protein or drug and presenting with fever, rash, and arthralgia. Diagnosis is clinical from the timing and triad with low complement and possible immune-complex markers, and treatment is stopping the trigger with antihistamines, NSAIDs, and corticosteroids for severe disease.
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What this article covers
- Overview
Definition: serum sickness is the prototypic type 3 (III) hypersensitivity reaction, caused by circulating immune complexes that deposit in tissues after exposure to a foreign protein or drug.
- Epidemiology
Historically from animal antisera: classically after equine antitoxin or antivenom.
- Risk factors
Exposure to foreign (especially non-human) protein: antivenoms, antitoxins, and chimeric or animal-derived monoclonal antibodies.
- Pathophysiology
Immune-complex formation: the host makes antibody against the foreign protein or drug, forming antigen-antibody complexes in slight antigen excess.
- Clinical features
Fever and malaise: early systemic symptoms.
- Differential diagnosis
Acute urticaria or IgE drug allergy: immediate onset (minutes to hours) without the delayed immune-complex timing (Urticaria).
- Diagnosis
Diagnose clinically from the delayed triad after a compatible exposure, supported by complement studies: the diagnostic basis is fever, rash, and arthralgia appearing about 1 to 2 weeks after…
- Management
First-line, stop the offending agent and avoid re-exposure, which is the essential step.
- Complications
Glomerulonephritis: immune-complex renal involvement, usually transient.
- Prognosis
Self-limited and favorable: most cases resolve within 1 to 2 weeks after the trigger is stopped.
- Prevention
Avoid re-exposure to the identified trigger and document it clearly.
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Related articles
- Urticaria
Urticaria is transient, pruritic, edematous wheals from mast cell histamine release, classified by duration into acute (under 6 weeks) and chronic (6 weeks or longer, usually spontaneous/idiopathic). Diagnosis is clinical with minimal testing, and treatment is stepwise second-generation H1 antihistamines up-titrated as needed, adding omalizumab for refractory chronic disease.
- Anaphylaxis
Anaphylaxis is an acute, potentially fatal systemic hypersensitivity reaction from massive mast cell and basophil mediator release, presenting within minutes as skin, respiratory, cardiovascular, and gastrointestinal involvement after allergen exposure. It is a clinical, treat-first diagnosis, and intramuscular epinephrine is the immediate life-saving therapy.