This double-blind, randomized, crossover study compared the incidence of nasal burning and stinging, as well as overall tolerability of the currently marketed formulation of Rhinalar (original formulation) to a new formulation of Rhinalar containing less propylene glycol. In addition, patient and investigator subjective evaluations were used to compare the effectiveness of the test medications in controlling the nasal symptoms of seasonal allergic rhinitis. A total of 122 patients were enrolled in this 4-week trial. Each patient received one formulation of Rhinalar for 2 weeks and then crossed over to receive the alternate formulation for an additional 2 weeks. Eighteen patients withdrew from the trial prematurely. Ten patients were lost to follow-up and eight withdrew due to side effects and/or inadequate therapeutic response. Statistical comparisons of patient evaluations of nasal burning and stinging with the two formulations of Rhinalar showed a very significant difference in terms of severity (P less than .001), duration (P less than .001), and tolerability (P = .006) in favour of the new formulation. A reduction in severity of throat irritation with the new formulation was also shown to be statistically significant (P = .006). Nausea, headache, and other side effects including watery eyes, taste perversion, and runny nose were seldom reported with either test medication. Both formulations were shown to be equally effective in relieving the nasal symptoms of seasonal allergic rhinitis. The considerable reduction in nasal burning and stinging and throat irritation with the new formulation of Rhinalar was shown to enhance patient acceptability and may lead to better compliance.