Sweat hair does not grow longer the more you shave because the hair follicle is the factor that determines whether sweat hair grows or not.
The amount of sweat hair on the human body is usually fixed because sweat hair grows from hair follicles, which are determined during fetal life. The growth of sweat hair is determined by the hair follicle, because shaving sweat hair will not affect the hair follicle, so sweat hair will not grow longer and longer.
Sweat hair has a protective effect on the body, it can keep you warm when it is cold; in hot times, it cools down the body through sweating.
If you often shave sweat hair, you may accidentally hurt the hair follicles, thus causing folliculitis, but also may damage the skin, resulting in skin pigmentation or even scars, etc. It is recommended that you want to remove sweat hair can be carried out in a regular hospital.