The symptoms of alopecia are obvious, and its examination is selected appropriately depending on the relevant etiology. There are three main types of common hair loss: one is neurogenic alopecia, one is seborrheic alopecia, and then a mixture of both. Some people also classify hair loss into male pattern baldness, female pattern baldness, patchy baldness, congenital alopecia, traumatic alopecia, hair cycle disorder, and many other types. In fact, hair has a root just like a planted tree. This root is medically called a hair follicle, and the follicle is like a seed, and the bud that comes out of the skin is the hair. The hair follicle grows at a rate of about 0.4mm per day for 2-6 years, after which the hair is shed and a new hair grows after a resting period of 3 months. So on and so forth, if there is no accident, a hair follicle can grow 20 times again and again, so every day there is hair loss and new hair growth. It is normal to lose about 50-l00 hairs per day. But the hair follicle is also very delicate, if encounter his master in long-term mental tension, malnutrition or other physical (such as long-term scratching hair, radioactive material irradiation), chemical (such as excessive perm hair, drugs, etc.) cause hair follicle discomfort, will cause excessive hair loss, or even a piece of hair loss, this is what we call baldness or ghost shaving alopecia, but if the hair follicle is not destroyed, as long as But if the hair follicles are not destroyed, the hair will slowly grow back as soon as the factors causing discomfort to the follicles are lifted. However, if you have destroyed the hair follicle because of burns, scalds, infections, trauma, etc., then it is impossible for it to grow back. Androgenic baldness is due to the fact that some hair follicles contain a kind of androgen receptor, the hair follicle containing the receptor itself does not have any effect on hair growth, but if it meets an androgen (dihydrotestosterone) will cause some changes, so that the hair follicle itself atrophy, degeneration, or even necrosis, this atrophy degeneration of the hair follicle can only grow a little bit of hair or grow hair. This atrophied and degenerated hair follicle can only produce a small amount of hair or no hair. These androgen receptor hair follicles are mostly genetic and are concentrated on the forehead and the top of the head, so the consequence is baldness. The root cause of hair loss must be eliminated in order to address the root cause of hair loss. Changing the structure of hair follicles and eliminating androgen receptors is not yet medically possible, and suppressing androgens (dihydrotestosterone) through drugs is not a good method in terms of long-term gains and losses. Although this method does not achieve the density of the original hair, it can achieve a very good cosmetic result. We can also plant hair follicles on the eyebrows, beard, pubic hair and areas that do not grow hair due to eccrine injury.