Should we prescribe oral corticosteroids for a patient with a diltiazem‑induced rash and intense pruritus?

Management of Diltiazem-Induced Rash with Pruritus

Yes, prescribe oral corticosteroids at prednisone 0.5-1 mg/kg/day for this diltiazem-induced rash with intense pruritus, but only after immediately discontinuing diltiazem. 1, 2

Immediate Action Required

• Stop diltiazem immediately and permanently - this is a drug hypersensitivity reaction that will not resolve with continued exposure and may progress to severe cutaneous reactions including erythroderma or Stevens-Johnson syndrome. 3
• Diltiazem causes cutaneous reactions more frequently than other calcium channel blockers, with documented cases progressing from initial rash to generalized erythrodermia within days. 3

Oral Corticosteroid Regimen

For moderate-to-severe rash with intense pruritus:

• Start prednisone 0.5-1 mg/kg/day (typically 30-60 mg daily for average adult). 1, 2
• Continue for 7-14 days until rash improves to grade 1 or resolves. 1
• Mandatory taper over 2-4 weeks even after short courses to prevent rebound flare and adrenal insufficiency. 4, 1, 2

Adjunctive therapy:

• Add oral antihistamines (cetirizine 10 mg daily or hydroxyzine 10-25 mg four times daily) for pruritus control throughout treatment. 4, 2
• Prescribe proton pump inhibitor prophylaxis for gastric protection with corticosteroid doses. 1, 2

Critical Monitoring Parameters

Watch for progression to severe reactions:

• Monitor for facial/neck edema, mucosal involvement (oral, conjunctival), or soft palate swelling - these indicate Grade 3 toxicity requiring hospital admission. 4
• Assess for systemic symptoms: fever, eosinophilia, or organ involvement (DRESS syndrome). 5
• If any signs of airway involvement develop, admit immediately for continuous monitoring. 4

Common Pitfalls to Avoid

• Never use prophylactic corticosteroids or antihistamines at diltiazem initiation - this approach has proven ineffective and paradoxically increases rash incidence in drug hypersensitivity reactions. 5
• Do not exceed prednisone 2 mg/kg/day as higher doses provide no additional benefit and increase toxicity. 1
• Avoid abrupt discontinuation of steroids after courses >2 weeks or doses >1 mg/kg/day. 1

Alternative Calcium Channel Blocker Considerations

• Cross-reactivity exists but is unpredictable - patch testing documented positive reactions to diltiazem with either nifedipine or verapamil in some patients, while others tolerated alternative agents without problems. 3
• If calcium channel blocker therapy remains necessary, consider controlled administration of nifedipine or amlodipine only after complete resolution of rash (minimum 4-6 weeks), with close monitoring for recurrence. 3
• Patch testing 2-6 months after resolution can identify specific allergen and guide safe alternatives. 4, 3

Expected Clinical Course

Resolution typically occurs within 10-12 days after discontinuing diltiazem with appropriate corticosteroid and antihistamine therapy. 3