Oral immunotherapy in birch pollen hay fever

Previous controlled trials with oral administration of allergen have not demonstrated any treatment effect in patients with allergic rhinoconjunctivitis or asthma. In the present double-blind, placebo-controlled trial, we have tested the effect of oral immunotherapy in adult patients with birch pollinosis. Thirty-nine patients completed this 18-month study comprising two birch pollen seasons. The patients received enterosoluble capsules daily, and the actively treated patients reached a cumulated dose of 280 times 10(6) biologic units of birch pollen extract, which is about 200 times higher than the dose used in conventional subcutaneous immunotherapy. We found a significant decrease in eye symptom scores and conjunctival sensitivity to birch pollen, as determined by conjunctival provocation test, as well as a numerical but nonsignificant decrease in nasal symptom scores, nasal sensitivity as determined by nasal provocation test, and antiallergic medication. The treatment was safe, and only a few slight side effects were observed. We thus conclude that our study demonstrates a clinical effect of oral immunotherapy in birch pollinosis.