Mugwort sensitization associated with chronic urticaria - could explain the benefit of elimination diets

Mugwort weed pollen is known to cross-react with a variety of spices and vegetables that are typically part of elimination diets used in the treatment of chronic urticaria (CU). This cross-reactivity is part of the well-described oral allergy syndrome that is reported in up to 45% patients with allergic rhinitis.

This study investigated the association between CU and allergic sensitization to mugwort pollen, and compared aeroallergen skin prick test results between 200 patients with and without CU, and with or without allergic rhinitis.

CU patients with coexisting allergic rhinitis were more than twice as likely to be sensitized to mugwort as subjects not suffering from CU (67 vs. 30%).

Ragweed (another pollen associated with oral allergy syndrome), cat, rat and mite sensitization were also significantly associated with CU.

Patients with CU had more positive aeroallergen skin tests than patients without CU.

Mugwort sensitization was associated with CU, possibly contributing to beneficial effect of some elimination diets.

Mugwort has also been implicated in Pollen-Food Allergy Syndrome (PFAS) or Oral Allergy Syndrome (OAS). Here are some typical cross-reactive associations:

BIRCH - Apple, peach, apricot, hazelnut, potato, carrot, celery
RAGWEED - Banana, cucumber, cantaloupe, watermelon, zucchini, cucumber
MUGWORT - Celery, onion, mustard, cabbage


Cross-reactivity in Pollen-Food Allergy Syndrome (PFAS) or Oral Allergy Syndrome (OAS) (click to enlarge the image).

References:

Increased Allergic Sensitization to Mugwort in Chronic Urticaria. de Vos G. · Kravvariti E. · Collins J. · Tavdy A. · Nazari R. · Hudes G. · Rosenstreich D. Dermatology 2012;225:141–146 (DOI: 10.1159/000342356)

Image source: Urticaria, Wikipedia, public domain.