The cost of treatment for ragweed hay fever can vary considerably. The newer classes of antihistamines are purported to be effective and without major side effects, but they are costly. This study compared the cost-effectiveness of terfenadine and chlorpheniramine/pseudoephedrine. We found that the maximum use of a low dose of chlorpheniramine/pseudoephedrine was effective and without major daytime sedation and should be considered when treatment for ragweed-induced allergic rhinitis is begun.