Oily hair is a result of excessive production of oil by the glands in the scalp because of several causes – heredity hair that’s very fine in texture hormonal fluctuations in the menstrual cycle or as a side effect in people who use androgenic hormones to bulk up body mass. Some people also develop oily hair if there is too much shampoo residue left over on the hair because of insufficient rinsing. Health.india.com tip for controlling oil in the hair: Tea contains an astringent substance called tannic acid; this helps to prevent the buildup of excessive oil on the scalp