A formula (KSS formula) containing the pith of Citrus tangerine Hort. et Tanaka (Kitsuraku), the rhizome of Zingiber officinale (Shokyo), and brown sugar has been traditionally used in China for the treatment of discomfort and cold sensation in the abdomen after ingestion of large amounts of alcohol. We evaluated the clinical effectiveness of this formula on signs and symptoms of alcohol hangover (AH). Of the twenty-two symptoms listed, significant decreases in severity scores were shown in nausea, vomiting, and diarrhea when the formula was administered in scheduled prophylactic doses. The score in overall well-being, ranging from 0 to 100 (worst possible condition), was 68.9 +/- 16.5 (mean +/- SD) in the control group and it decreased to 46.9 +/- 27.3 and to 44.4 +/- 26.4 in the two groups that included a dosing point prior to alcohol ingestion. Regardless of dosing schedules, KSS formula did not alter the time required for complete recovery from AH symptoms. These findings suggest the possibility that KSS formula may become a candidate for AH remedy when administered prophylactically.