Serum sickness

Overview
Serum sickness is a reaction to an antiserum derived from an animal source. It is a type of hypersensitivity, specifically immune complex (type 3) hypersensitivity. Serum sickness typically develops up to ten days after exposure to the antiserum, and symptoms are similar to an allergic reaction. However, it is different from anaphylaxis, since the symptoms are not instantaneous (onset is typically 2-4 weeks after exposure).

Pathophysiology
Serum sickness can be developed as a result of exposure to antibodies derived from animals. These serums are generally administered in order to prevent infection. When the antiserum is given, the human immune system can mistake the proteins present for harmful antigens. The body produces antibodies, which combine with these proteins to form immune complexes. These complexes can cause more reactions, and cause the symptoms detailed below. Serum sickness can also be caused by several drugs, notably penicillin based medicines.

Symptoms
Symptoms can take as long as fourteen days after exposure to appear, and may include:


 * Rashes
 * Joint pain (arthralgia)
 * Fever
 * Lymph node swelling (lymphadenopathy)
 * Shock
 * Decreased blood pressure (hypotension)
 * Enlarged spleen (splenomegaly)

Treatment
Symptoms will generally disappear on their own, although corticosteroids may be prescribed in the most severe forms. Antihistamine may also be used.