Thirty-two patients with seasonal allergic rhinitis due to weed pollen were treated beginning prior to the weed pollen season of 1974 with either 4% cromolyn sodium or placebo nasal spray. The patients were followed on treatment with symptom diary cards and bi-weekly physician examinations for a period of 10 weeks. Radioallergosorbent (RAST) titres for the major weeds in the Denver area (ragweed, Russian thistle, and sage) were determined before the weed pollen season, and one and three months after the weed pollen season.

There was no significant difference in symptom scores between the 4% cromolyn sodium- and placebo-treated groups, nor objective evidence on bi-weekly examinations by a physician to suggest differences in the two groups. Significant differences in favor of the 4% cromolyn-treated group were noted in the amount of antihistamines taken for symptomatic relief during the weed pollenating season, suggesting some protective effect of the drug. The clinical significance of this finding is not clear. Selecting patients with high baseline RAST titres for one or more of the major weeds did not alter the results of the study.

In a second double-blind study twenty-two patients reporting to the allergy clinic with symptomatic seasonal allergic rhinitis due to weeds were randomly assigned to receive 4% cromolyn sodium or placebo nasal spray and followed through the weed pollen season. There was no difference between the two groups in either symptom scores or use of antihistamines for asymptomatic relief.