What is an ID (Infectious Disease) reaction?

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Last updated: May 13, 2025View editorial policy

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From the Guidelines

ID reactions, also known as dermatophytid, are a cell-mediated host response to dermatophytes and should not be confused with a drug reaction, with treatment focusing on symptomatic relief using topical or oral corticosteroids. When considering the management of ID reactions, it is essential to understand that they represent a secondary skin reaction occurring at a site distant from the primary skin condition, often associated with fungal infections 1. Key characteristics of ID reactions include:

  • A pruritic, papular eruption
  • Often appears around the outer helix of the ear
  • Represents a cell-mediated host response to the dermatophyte after effective therapy has been initiated
  • Does not warrant cessation of systemic antimycotic therapy For symptomatic relief of ID reactions, the following treatments can be considered:
  • Topical corticosteroids
  • Oral corticosteroids, if very severe It is crucial to address both the primary condition and the ID reaction, with specific treatments depending on the cause of the primary condition 1. In the context of tinea capitis, ID reactions may accompany treatment initiation, and their management should be focused on providing symptomatic relief without interrupting the treatment of the primary fungal infection 1.

From the Research

ID Reaction Definition

  • ID reactions are a type of secondary inflammatory reaction that develops from a remote localized immunological insult 2
  • They can be caused by various fungal, bacterial, viral, and parasitic infections, with superficial fungal infections, especially tinea pedis, being the most common cause 2

Clinical Presentations

  • ID reactions exhibit multiple clinical presentations, including:
    • Localized or widespread vesicular lesions
    • Maculopapular or scarlatiniform eruptions
    • Erythema nodosum
    • Erythema multiforme
    • Erythema annulare centrifugum
    • Sweet's syndrome
    • Guttate psoriasis
    • Autoimmune bullous disease 2

Treatment

  • The most important aspect of therapy involves the identification and adequate treatment of the underlying infection or dermatitis 2
  • Oral antifungal agents, such as fluconazole, itraconazole, and terbinafine, can be used to treat dermatophytic infections, but their effectiveness may vary 3, 4, 5
  • In some cases, oral antifungal therapy can exacerbate inflammatory reactions, and topical and/or systemic corticosteroids may be necessary to reduce the inflammation 3

Antifungal Agents

  • Itraconazole, fluconazole, and terbinafine are commonly used oral antifungal agents for the treatment of dermatophytic infections 4, 5
  • However, resistance to these drugs is being seen increasingly, and their effectiveness may be limited in certain cases 4
  • Drug interactions should be considered when prescribing oral antifungal agents, as some agents, such as itraconazole and fluconazole, can interact with other medications 6

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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