Provided is a skin irritation suppressant for transdermal preparations, said skin irritation suppressant having an acknowledged effect of adequately reducing skin irritation caused by drugs. Also provided is a transdermal preparation containing said skin irritation suppressant. One embodiment of the invention is a skin irritation suppressant for reducing skin irritation caused by pharmaceutical adjuvants used in drugs and transdermal preparations other than drugs, said skin irritation suppressant comprising sterol compounds selected from a group comprising cholesterol, cholesterol derivatives and cholesterol analogs. Said drug is one or more basic drugs selected from a group comprising tolterodine, asenapine, bisoprolol, risperidone, nicotine, and citalopram, and pharmacologically acceptable salts thereof.本發明之目的為提供已確認藥物具充分的降低皮膚刺激效果之經皮吸收製劑用皮膚刺激抑制劑，以及摻混該皮膚刺激抑制劑之經皮吸收製劑為目的。本發明之一實施方式係提供一種皮膚刺激抑制劑，其係由選自膽固醇、膽固醇衍生物以及膽固醇類似物所成群之固醇類化合物構成，且用以降低使用於藥物以及藥物以外的經皮吸收製劑之摻混劑造成之對皮膚刺激之皮膚刺激抑制劑，該藥物係1種以上選自得舒妥(tolterodine)、阿森那平(asenapine)、康肯(bisoprolol)、賽力多(risperidone)、尼古丁及解憂喜(citalopram)所成群之鹼性藥物，及其藥學上許可之鹽。
