What could be causing nighttime hives (urticaria) in a patient with a history of coccidioidomycosis (valley fever) and no recent changes in medication or diet?

Nighttime Hives in a Patient with Valley Fever History

Your nighttime-only hives are most likely idiopathic chronic urticaria with a nocturnal pattern, and you should start treatment with a nonsedating H1-antihistamine taken in the evening, with the dose potentially increased up to 4 times the standard amount if needed.

Initial Treatment Approach

• Begin with a nonsedating H1-antihistamine such as cetirizine, desloratadine, fexofenadine, levocetirizine, or loratadine taken once daily in the evening to ensure peak drug levels when symptoms occur 1
• Cetirizine has the shortest time to maximum concentration, which may be advantageous for rapid symptom control 1
• If standard dosing fails after 1-2 weeks, increase the antihistamine dose up to 4 times the manufacturer's recommended dose, as this has become common practice when benefits outweigh risks 1
• Avoid aggravating factors including overheating at night, alcohol, aspirin, and NSAIDs (especially important given your valley fever history, as some antifungals interact with certain medications) 1

Why Valley Fever Is Unlikely the Direct Cause

• Valley fever (coccidioidomycosis) rarely causes isolated urticaria as a clinical manifestation 1, 2
• The most common presentation of valley fever is respiratory symptoms appearing 1-3 weeks after infection, not isolated skin manifestations 1, 2, 3
• Cutaneous manifestations of coccidioidomycosis are rare and typically indicate disseminated disease with serious infection, not isolated nighttime hives 4
• Your lack of new medications or foods makes drug-induced or allergic urticaria less likely 1

Consider These Underlying Patterns

• Approximately 30% of chronic urticaria cases have an autoimmune etiology, though this doesn't change initial management 1
• Nocturnal worsening suggests adjusting medication timing to achieve highest drug levels when symptoms peak 1
• Physical triggers like pressure from bedding or warmth under covers may contribute to nighttime symptoms 1

If First-Line Treatment Fails

• Add an H2-antihistamine (like ranitidine or famotidine) to the H1-antihistamine regimen 1
• Consider adding a sedating antihistamine at bedtime (such as hydroxyzine or diphenhydramine) for additional control during sleep hours 1
• Antileukotriene agents (montelukast) can be added for resistant cases 1
• Short courses of oral corticosteroids should be reserved only for severe acute exacerbations, not routine management 1

Important Caveats

• Avoid aspirin and NSAIDs, as approximately 10-40% of patients with chronic urticaria experience worsening with these medications 1
• If individual wheals last longer than 24 hours, consider urticarial vasculitis and pursue skin biopsy 1
• If symptoms persist beyond 6 weeks despite treatment, further evaluation may be warranted, though 50% of chronic urticaria cases resolve within 6 months 1
• Cooling antipruritic lotions (1% menthol in aqueous cream) can provide symptomatic relief 1

When to Seek Further Evaluation

• If you develop angioedema (swelling of lips, tongue, or throat), seek immediate medical attention 1
• If hives are accompanied by systemic symptoms (fever, joint pain, weight loss), further workup is needed to exclude underlying systemic disease 1
• If standard antihistamine therapy at increased doses fails after 2-4 weeks, consider referral to dermatology or allergy for potential immunomodulating therapies 1