- Use of allergy medications, within a timeframe relative to Visit 1, that would prevent the medication from being eliminated and/or have an effect. Exclusionary timeframes relative to Visit 1 for five common allergy treatments are noted below Intranasal cromolyn (<=2 weeks from Visit 1). Intranasal or systemic decongestants (<=3 days from Visit 1). Intranasal or systemic (other than oral) antihistamines (<=3 days from Visit 1).