Larger follicles, more coverage Minoxidil works by enlarging miniaturized hair follicles and reversing the miniaturization process, Hitzig says. It prolongs the growth phase of the hair cycle, which allows the hair to become longer and thicker. And with more follicles in the growth phase at the same time, there's greater coverage of the scalp. These can include thyroid problems, anemia, a side effect of medication, or even alopecia areata, which is an autoimmune condition that causes hair to fall out in clumps. Although many women experience thinning hair in the perimenopausal and menopausal years, the problem is only partially related to hormones, according to Dr. Robert Scheinberg, a San Diego-area dermatologist and a clinical professor at the University of California at San Diego School of Medicine.
Hair falls out because of the way the hair follicle metabolizes testosterone, an inherited trait.
Testosterone shortens the life cycle of the hair, so it falls out sooner than it ordinarily would. At any given time, about 85 percent of hairs are in the growing phase, and the remainder are in the resting phase, Scheinberg notes. Balding occurs when hair falls out but has no replacement. Unlike men who lose hair in one place, women usually experience hair thinning evenly all over their scalp. But of course, she notices it before that.