CAUSE 1:
Shaving
When you shave, you cut hair off ar, or just below, the surface of the skin. If the hair is darker than your skin color, your skin can appear to have a dark stain, but it's really just subsurface hair. Instead of shaving, try waxing it gets rid of the hair from deeper level.
CAUSE 2:
Buildup of Dead Skin Cells
Dark spot under your arms can be the result of dead skin cells thatare trapped in microscopic hills and valleys.
CAUSE 3:
Deodorant usage
In theory, some ingredients in these products perthaps fragrance could react with your skin and cause discoloration.
CAUSE 4:
Acanthosis Nigricans
This medical condition causes light-brown to black markings on the neck, under the arms, or in the groin. It typically ocurs in people over weight. If this applies to you, see a doctor.
