What is the cause of a generalized urticarial rash after using a towel with mold?

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Last updated: April 20, 2025View editorial policy

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From the Guidelines

If you've developed a generalized urticarial rash after using a towel with mold, you should first stop using the contaminated towel and wash the affected skin with mild soap and water. Take an oral antihistamine like cetirizine (10mg once daily), loratadine (10mg once daily), or diphenhydramine (25-50mg every 6 hours) to reduce itching and inflammation, as antihistamines are the mainstay of therapy for urticaria 1. Apply a topical corticosteroid cream like hydrocortisone 1% to the affected areas 2-3 times daily for up to 7 days. Cold compresses can also help relieve symptoms. If the rash is severe, spreading, or accompanied by difficulty breathing, facial swelling, or other concerning symptoms, seek immediate medical attention. This reaction is likely due to an allergic response to mold spores on the towel, which can trigger immune responses when they contact skin, especially in sensitive individuals 1. To prevent future reactions, ensure towels are completely dry before storing, wash them regularly in hot water, and store them in well-ventilated areas to prevent mold growth. Additionally, minimizing nonspecific aggravating factors such as overheating, stress, alcohol, and certain drugs can help alleviate symptoms 1. It's also important to note that while the cause of the condition may be unlikely to be found, the prognosis for eventual recovery from ordinary urticarias is excellent 1.

Some key considerations for management include:

  • Avoiding NSAIDs in aspirin-sensitive patients with urticaria 1
  • Using cooling antipruritic lotions, such as calamine or 1% menthol in aqueous cream, to soothe the skin 1
  • Providing patients with clearly written information sheets to help them understand their condition and its management 1

From the Research

Generalized Urticarial Rash

  • A generalized urticarial rash is a cutaneous syndrome characterized by dermal edema (wheal) and erythema (flare) that blanches with pressure 2
  • The lesions typically last less than 24 hours and are usually pruritic

Causes of Urticarial Rash

  • Urticarial rash can be caused by various factors, including hypersensitivity reactions to certain substances or medications 3
  • In some cases, the cause of the urticarial rash may be unclear, and further testing may be necessary to determine the underlying cause

Treatment of Urticarial Rash

  • Antihistamines are the mainstay of treatment for urticarial rash, and newer nonsedating antihistamines have reduced adverse effects compared to older antihistamines 2
  • However, antihistamines can also cause hypersensitivity reactions, including urticaria, in some individuals 3

Relevance to Mould Exposure

  • There is no direct evidence in the provided studies to suggest a link between mould exposure and generalized urticarial rash
  • However, it is possible that mould exposure could trigger an allergic reaction or hypersensitivity response in some individuals, which could manifest as a urticarial rash

Discontinuation of Medication

  • When discontinuing medication, it is essential to consider the potential for adverse drug withdrawal events (ADWEs) 4, 5
  • Gradually tapering off certain medications, such as those that act on the central nervous system, can help minimize the risk of ADWEs 4, 5

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Treatment of urticaria. An evidence-based evaluation of antihistamines.

American journal of clinical dermatology, 2001

Research

Urticaria caused by antihistamines: report of 5 cases.

Journal of investigational allergology & clinical immunology, 2009

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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