The invention relates an assay useful for screening and identifying compounds as modulators of lower alkyl phenol activation of TRPA1. Thymol, a lower alkyl phenol anti-infective and the active ingredient in, e.g., mouthwashes, is stringent and has an objectionable burning taste sensation. Thymol activates the transient receptor potential like ion channel TRPA1. The assay described and claimed herein involves measurement of activation of TRPA1 and enables the screening of compounds that inhibit lower alkyl phenol, or thymol activation of TRPA1. Inhibitors of thymol activation of TRPA1 can be used to prevent the objectionable taste of thymol in medical uses where taste limits acceptance.