...In one series of tests of biotin in balding men, biotin was used instead of estrogen in a penetrating cream applied to the scalp. The biotin cream (which also contained niacin, vitamin B-3, a histamine releaser) was applied daily at bedtime. The biotin content was 0.25 to 1.0 percent. Histamine release, such as is triggered by niacin, is essential for cell growth and reproduction. Histamine release causes a normally healing wound to become red and itchy. In addition, a shampoo which contained various conditioners to reduce hair breakage and cystine, cysteine, and methionine (amino acids in hair) was used three times a week. There were no side effects with the biotin. Within six to eight weeks, 89 percent of the nearly 1,200 men in the study (ranging in age from 15 to 69) showed marked reduction in hair fallout, from losses of 100 to 350 hairs per day to a daily average loss of less than 50 hairs. Regrowth of hair also occurred in the biotin study. Although incomplete at the time the paper was published, preliminary data indicated that regrowth (150 to 200 3/4-inch or longer hairs per square inch in bald areas) occurred in about 50 to 75 percent of the subjects. Younger men in the study had better results.