RESUMEN
Patients with birch pollen allergic rhinitis were treated locally, out of season, in the nasal cavity with capsaicin (30 microM) or saline. The capsaicin treatment resulted in a statistically significant reduction of symptoms upon allergen challenge, which lasted for 2 months. Saline had no effect on the symptom score upon allergen challenge. Neither capsaicin nor saline treatment had any effect on allergen challenge-induced nasal mucosal swelling monitored by acoustic rhinometry. Allergen challenge-induced eosinophil migration to the nasal mucosa was affected by neither capsaicin nor the saline treatment. The finding that capsaicin treatment reduces allergic symptoms indicates that selective, non-peptide neurokinin receptor antagonists may be an alternative in the future in the treatment of nasal allergy. However, owing to the pain involved in local capsaicin treatment this treatment is unlikely to be of clinical use.