Drug hypersensitivity

Drug hypersensitivity refers to an immune system-mediated reaction to a drug, where the body's immune response is triggered against a substance that is otherwise harmless to most people. This condition is a subset of drug reactions that encompasses a wide range of clinical syndromes, including immediate reactions like anaphylaxis, and delayed reactions such as drug rash with eosinophilia and systemic symptoms (DRESS) syndrome, Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN).

Causes

Drug hypersensitivity reactions are caused by the immune system's response to medications. The mechanisms behind these reactions can be classified into two main types: immediate reactions mediated by IgE antibodies and delayed reactions mediated by T cells. Common drugs that can cause hypersensitivity reactions include antibiotics, particularly beta-lactams; nonsteroidal anti-inflammatory drugs (NSAIDs); and certain anticonvulsants.

Symptoms

Symptoms of drug hypersensitivity can vary widely, from mild rashes to severe, life-threatening conditions such as anaphylaxis. Other symptoms may include fever, urticaria (hives), angioedema (swelling), respiratory symptoms, and organ-specific reactions. The onset of symptoms can be immediate, occurring within minutes to hours after drug exposure, or delayed, appearing days to weeks after exposure.

Diagnosis

Diagnosis of drug hypersensitivity involves a detailed patient history, including the timing of symptom onset relative to drug exposure, and may also include skin tests, serum specific IgE tests, and drug provocation tests. However, the diagnostic process can be challenging due to the wide range of potential symptoms and the lack of specific diagnostic tests for many drugs.

Treatment

The primary treatment for drug hypersensitivity is the immediate discontinuation of the suspected drug. Management of symptoms may include administration of antihistamines, corticosteroids, and, in cases of anaphylaxis, epinephrine. In some cases, desensitization procedures may be performed, allowing the patient to safely receive a medication that has previously caused a hypersensitivity reaction.

Prevention

Prevention of drug hypersensitivity reactions involves the careful selection of medications, with consideration of a patient's drug allergy history. In healthcare settings, maintaining accurate and up-to-date patient records can help prevent inadvertent exposure to drugs that have previously caused hypersensitivity reactions.