Nettle Allergy: a Review and Clinical Perspective

Abstract

Stinging nettle (Urtica dioica) is a common cause of contact urticaria worldwide; however, its clinical relevance in allergic rhinitis and aeroallergen immunotherapy has not been well established. This presents a clinical conundrum to the physician and can potentially impact the effectiveness of treatment of allergic rhinitis in nettle sensitized patients. The objectives of this article are to review the available literature regarding the geographic distribution of nettle, allergen(s) involved, cross-reactivity, role in allergic rhinitis, immunotherapy efficacy, and provide a clinical perspective on the evaluation and treatment of nettle sensitized patients. Stinging nettle (Urtica dioica) is a bi-annual pollinator with worldwide distribution and wide use in homeopathy. Limited data suggest that nettle pollen allergens may be considered clinically relevant and that nettle pollen allergy may be underestimated. More recent allergomic analysis of nettle pollen has revealed protein allergens including an osmotin and a pectin esterase which may implicate cross-reactivity with other pollens and foods. One study describes in vivo nettle immunotherapy. Overall, there is a paucity of medical literature evaluating the role of nettle in allergic rhinitis with even fewer studies assessing the clinical efficacy of nettle immunotherapy. Cross-reactivity patterns with other pollens and foods remains to be fully elucidated. Given the immense medical and economic impact of allergic rhinitis and the worldwide distribution of nettle, prospective randomized controlled trials are needed to evaluate the possible contribution of nettle allergy and efficacy of nettle immunotherapy.