Drug eruptions

Drug eruptions

Drug eruptions refer to adverse skin reactions that occur as a result of taking medication. These reactions can vary widely in appearance, severity, and duration, depending on the type of drug involved and the individual's response. Drug eruptions can affect any area of the skin and, in some cases, mucous membranes. They are a common reason for patients to seek dermatological advice and can sometimes be life-threatening, necessitating immediate medical attention.

Causes

Drug eruptions are caused by an adverse reaction to a drug. This can be due to an allergic reaction, where the body's immune system mistakenly identifies the drug as a harmful substance, or a non-allergic reaction, which can occur as a direct effect of the drug on the skin. Common drugs that can cause eruptions include antibiotics (especially penicillins and sulfonamides), nonsteroidal anti-inflammatory drugs (NSAIDs), antiepileptic drugs, and chemotherapy agents.

Types

There are several types of drug eruptions, each with distinct characteristics:

• Exanthematous (maculopapular) eruptions: The most common type, characterized by red patches and bumps spread evenly across the body.
• Urticaria: Also known as hives, these are itchy, raised welts that can appear anywhere on the body.
• Fixed drug eruption: A localized reaction that occurs at the same site each time the drug is taken.
• Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN): Severe, life-threatening reactions characterized by widespread skin necrosis and detachment.
• Drug rash with eosinophilia and systemic symptoms (DRESS): A serious condition that includes a rash, fever, enlarged lymph nodes, and involvement of internal organs.

Diagnosis

Diagnosis of drug eruptions involves a careful history taking, including the timing of drug intake and the onset of symptoms. Skin biopsy and blood tests may be performed to rule out other conditions and to confirm the diagnosis. In some cases, patch testing or drug challenge tests are conducted under close medical supervision to identify the causative agent.

Treatment

The first step in treating a drug eruption is to discontinue the offending drug, if known. Treatment then focuses on managing symptoms and may include the use of antihistamines for itching, corticosteroids for inflammation, and supportive care for more severe reactions. In cases of SJS or TEN, hospitalization in a burn unit or intensive care unit may be necessary.

Prevention

Preventing drug eruptions involves avoiding known triggers and informing healthcare providers of any previous drug reactions. In some cases, desensitization protocols may be used to gradually introduce the drug to the patient's system, reducing the risk of a reaction.