Provided is a skin irritation suppressant for transdermal preparations, having a sufficient reduction effect of skin irritation due to a drug. Also provided is a transdermal preparation comprising the skin irritation suppressant. One embodiment of the invention is a skin irritation suppressant for suppressing the skin irritation due to a drug and a pharmaceutical ingredient to be used in a transdermal preparation other than the drug, the skin irritation suppressant comprising a sterol compound selected from the group consisting of cholesterol, cholesterol derivatives and cholesterol analogs, and the drug is one or more basic drugs selected from the group consisting of tolterodine, asenapine, bisoprolol, risperidone, nicotine and citalopram, and their pharmaceutically acceptable salts.
