Type your tag names separated by a space and hit enter

ID Reaction

ID Reaction is a topic covered in the 5-Minute Clinical Consult.

To view the entire topic, please or purchase a subscription.

Medicine Central™ is a quick-consult mobile and web resource that includes diagnosis, treatment, medications, and follow-up information on over 700 diseases and disorders, providing fast answers—anytime, anywhere. Explore these free sample topics:

Medicine Central

-- The first section of this topic is shown below --



A generalized skin reaction associated with various infectious (fungal, bacterial, viral, or parasitic) or inflammatory cutaneous conditions distant from the primary disease site (1)

  • “Id” is often combined with a root to reflect the causative factor (i.e., bacterid, syphilid, and tuberculid). Dermatophytid is the most frequently referenced id reaction. A dermatophytid is an autosensitization reaction in which a secondary cutaneous reaction occurs at a site distant to a primary fungal infection. The eruption typically begins within 1 to 2 weeks of the onset of the main lesion or following exacerbation of the main lesion.
  • Most commonly localized vesicular lesions, erythema nodosum, and erythema multiforme
  • System(s) affected: skin/exocrine
  • Synonym(s): dermatophytid, trichophytid, autoeczematization


  • Predominant age: all ages
  • Predominant sex: male = female
  • Predominant race: all races



Etiology and Pathophysiology

Precise pathophysiology is uncertain. Circulating antigens may react with antibodies at sensitized areas of the skin. An abnormal immune recognition of autologous skin antigens may also occur. Inflammation may lower the irritation threshold of the skin, and hematogenous spread of cytokines from the primary site of inflammation may also play a role (1).

  • Etiology
    • Infectious
      • Fungal infections: Trichophyton mentagrophytes, Trichophyton rubrum, Epidermophyton floccosum, and Candida spp.
      • Bacterial infections: Streptococcus pyogenes, Staphylococcus aureus, and Mycobacterium tuberculosis
      • Viral infections: HSV, Molluscum contagiosum, orf, and milker’s nodules
      • Parasitic infections: Sarcoptes scabiei and Leishmania spp.
    • Allergic
      • Id reactions occur in patients with nickel and aluminum allergy.
    • Miscellaneous
      • Id reaction rarely develops due to retained postoperative sutures, ionizing radiation, and blunt trauma.
      • Rarely, id reaction has been documented in patients receiving intravesical BCG live therapy for transitional cell carcinoma.

Risk Factors

  • Fungal infection of the skin, especially tinea pedis
  • Stasis dermatitis

General Prevention

  • Good skin hygiene (particularly in intertriginous areas) to minimize risk of developing fungal infections
  • Promptly treat any developing fungal infection.

Commonly Associated Conditions

  • Primary fungal infection
  • Stasis dermatitis

-- To view the remaining sections of this topic, please or purchase a subscription --


Stephens, Mark B., et al., editors. "ID Reaction." 5-Minute Clinical Consult, 27th ed., Wolters Kluwer, 2019. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116314/all/ID_Reaction.
ID Reaction. In: Stephens MB, Golding J, Baldor RA, et al, eds. 5-Minute Clinical Consult. 27th ed. Wolters Kluwer; 2019. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116314/all/ID_Reaction. Accessed March 20, 2019.
ID Reaction. (2019). In Stephens, M. B., Golding, J., Baldor, R. A., & Domino, F. J. (Eds.), 5-Minute Clinical Consult. Available from https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116314/all/ID_Reaction
ID Reaction [Internet]. In: Stephens MB, Golding J, Baldor RA, Domino FJ, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2019. [cited 2019 March 20]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116314/all/ID_Reaction.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC T1 - ID Reaction ID - 116314 ED - Stephens,Mark B, ED - Golding,Jeremy, ED - Baldor,Robert A, ED - Domino,Frank J, BT - 5-Minute Clinical Consult, Updating UR - https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116314/all/ID_Reaction PB - Wolters Kluwer ET - 27 DB - Medicine Central DP - Unbound Medicine ER -