Serum sickness is an immune system reaction to certain foreign proteins or medications. Unlike immediate allergic reactions like anaphylaxis, its onset is more gradual.
What is Serum Sickness
Serum sickness is a systemic immune reaction classified as a type III hypersensitivity response. It occurs when the immune system forms complexes of antibodies and foreign proteins that deposit in tissues, triggering inflammation.
This reaction primarily arises from exposure to foreign proteins in certain medications or biological products. Common triggers include antitoxins and antivenoms. Certain antibiotics, such as penicillin, cefaclor, and sulfonamides, can also induce serum sickness. Monoclonal antibodies used in treating autoimmune diseases or cancer, like rituximab and infliximab, and some vaccines are also potential causes.
Common Signs and Symptoms
Symptoms typically emerge 7 to 14 days after exposure to the triggering substance. However, if a person has been exposed previously, symptoms might appear more rapidly, within 1 to 3 days. Initial signs often include a general feeling of being unwell.
A characteristic feature is a skin rash, which can appear as hives (urticaria) or a morbilliform (measles-like) eruption, intensely itchy. This rash may start on the hands, feet, and trunk, spreading across the body. Joint pain, known as arthralgia, is also common, affecting areas like the knees, wrists, shoulders, and ankles.
Individuals also experience fever, sometimes reaching 104°F (40°C), and swelling of the lymph nodes. Swelling, or edema, can also affect the face, hands, and feet.
Understanding Serious Complications
While serum sickness often resolves without lasting issues, it can lead to more serious complications. These severe outcomes are rare but warrant careful attention. One potential complication is glomerulonephritis, an inflammation of the kidney’s tiny filtering units, which can impair kidney function. Symptoms of kidney involvement may include changes in urine output, swelling, and fatigue.
Other serious complications include vasculitis, inflammation of blood vessels throughout the body. Nerve damage, or neuropathy, and inflammation of the heart muscle, known as myocarditis, have also been reported. In rare cases, severe reactions can lead to laryngeal edema, which is swelling in the throat, or neurological issues such as Guillain-Barré syndrome.
It is important to seek immediate medical attention if severe symptoms develop, such as difficulty breathing or new neurological changes. Persistent or worsening symptoms, a fever above 100.4°F (38°C), or the appearance of a rash in the mouth, genital area, or with blisters necessitate prompt medical evaluation. Early recognition and medical consultation are important to mitigate the risk of these serious complications.
Managing Serum Sickness and Outlook
The primary approach to managing serum sickness involves discontinuing the substance that triggered the reaction. This step is sufficient for symptoms to resolve. Healthcare providers will guide patients on avoiding future exposure to the agent.
For relief from common symptoms, over-the-counter medications are recommended. Antihistamines can help alleviate itching and rashes, while nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen are effective for managing joint pain and fever. In more severe cases, a healthcare provider may prescribe oral corticosteroids for a short course, typically 7 to 10 days, to reduce inflammation.
The prognosis for serum sickness is favorable, with most individuals experiencing a full recovery without long-term effects. Symptoms subside within a few days to weeks after stopping the causative agent. While continued exposure to the offending substance can lead to prolonged or more severe reactions, proper medical management helps ensure a positive outcome.