Drug-Induced Acute Urticaria, Angioedema, Edema, and Anaphylaxis
- Drug-induced urticaria and angioedema occur, caused by a variety of mechanisms (see Table 23-1) and are characterized clinically by transient wheals (see Fig. 14-2) and angioedema (Fig. 14-6) causing extensive tissue swelling with involvement of deep dermal and subcutaneous tissues (see also Section 14). Angioedema is often pronounced on the face (Fig. 23-5A) or mucous membranes (tongue, Fig. 23-5B).
- In some cases, cutaneous urticaria/angioedema is associated with systemic anaphylaxis, which is manifested by respiratory distress, vascular collapse, and/or shock.
- Drugs causing urticaria/angioedema and anaphylaxis are listed in Table 23-5.
- Time from Initial Drug Exposure to Appearance of Urticaria
- IgE-Mediated. Initial sensitization, usually 7 to 14 days. In previously sensitized individuals, usually within minutes or hours.
- Immune Complex-Mediated. Initial sensitization, usually 7 to 10 days, but as long as 28 days; in previously sensitized individuals, 12 to 36 hours.
- Analgesics/Anti-Inflammatory Drugs. 20 to 30 minutes (up to 4 hours).
- Prior Drug Exposure.Radiographic Contrast Media. Twenty-five percent to 35% probability of repeat reaction in individuals with history of prior reaction to contrast media. β-blocker use may increase risk.
- Skin Symptoms. Pruritus, burning of palms, and soles with airway edema difficulties breathing.
- Constitutional Symptoms. IgE-mediated: Flushing, sudden fatigue, yawning, headache, weakness, and dizziness; numbness of tongue, sneezing, bronchospasm, substernal pressure, and palpitations; nausea, vomiting, crampy abdominal pain, diarrhea, and possibly arthralgia.
MANAGEMENT Identify and withdraw offending drugs. Antihistamines. H1 blockers or H2 blockers or combination. Systemic Glucocorticoids Intravenous. Hydrocortisone or methylprednisolone for severe symptoms. Oral. Prednisone, 70 mg, tapering by 10 or 5 mg daily over 1 to 2 weeks, is usually adequate. In Acute Severe Urticaria/Anaphylaxis
Epinephrine. 0.3 to 0.5 mL of a 1:1000 dilution subcutaneously, repeated in 15 to 20 minutes. Maintain airway. Intravenous access. Radiographic Contrast Media. Avoid use of contrast media known to have caused prior reaction. If not possible, pretreat patient with antihistamine and prednisone (1 mg/kg) 30 to 60 minutes before contrast media exposure.