Drug Eruptions

Skin Lesion: Morbilliform (measles-like) or maculopapular rash. It consists of bright red macules and papules that may become confluent. It is the most common type of drug reaction.

Classic Clues:

• Timeline: Typically appears 4–14 days after starting a new medication.
• Distribution: Starts on the trunk and spreads symmetrically to the limbs.
• Symptoms: Pruritus is the dominant symptom. No systemic toxicity.

Fixed Drug Eruption (FDE)

• The Clue: Solitary (or few) dusky red/purple oval macules that recur in the exact same location upon re-exposure to the drug.
• Vs Exanthematous: FDE is localized (often on genitals or lips), while exanthematous rashes are generalized and symmetrical.

Viral Exanthem

• The Clue: Associated with a viral prodrome (fever, sore throat, lymphadenopathy).
• Vs Drug Eruption: Viral rashes are more common in children; drug eruptions are more common in adults. History of new medication is the key differentiator.

🚨 URGENT Referral (SJS/TEN/DRESS) if:

• Mucosal Involvement: Ulcers/erosions of the eyes, mouth, or genitals.
• Nikolsky Sign: Skin peels off with slight lateral pressure (suggests epidermal necrolysis).
• Skin Pain: "Painful skin" rather than itchy skin is a major warning sign.
• Facial Edema & Eosinophilia: Suggests DRESS syndrome (Drug Reaction with Eosinophilia and Systemic Symptoms).
• Systemic Toxicity: High fever, lymphadenopathy, or organ dysfunction (liver/renal).

Immediate Actions:

• Stop the Offending Drug: The single most important step. Identify all new drugs started in the last 2 months.
• Documentation: Clearly document the drug allergy in the patient's record and provide an allergy card.

Symptomatic Treatment:

• Topical Corticosteroid: Medium-potency (Betamethasone) to reduce inflammation/itch.
• Antihistamine