METHODS

Design:

randomised placebo controlled trial.

Allocation:

unclear allocation concealment.*

Blinding:

blinded (patients, healthcare providers, and outcome assessors).*

Follow up period:

up to the end of grass pollen season.

Setting:

55 centres in Canada, UK, Germany, Belgium, Austria, Denmark, Sweden, and Norway.

Patients:

855 patients 18–65 years of age (mean age 35 y, 62% men) who had allergic rhinoconjunctivitis during grass pollen season for ⩾2 years and positive result on skin prick test to timothy grass (Phleum pratense). Exclusion criteria included history of asthma, anaphylaxis, or angio-oedema; forced expiratory volume₁ <70% predicted; non-grass induced allergic rhinitis; recurrent acute or chronic sinusitis; conjunctivitis, rhinitis, or asthma at randomisation; hypersensitivity to trial medication; and immunotherapy for allergens in the past 5–10 years.

Intervention:

oral P pratense …