Dark underarms is a condition that affects many women. I can be unsightly and even embarrassing to some. There are some women who will not wear clothes that exposes their underarms. Dark underarms has many causes including excessive shaving, chemicals, medical reasons, friction and the accumulation of dead skin. Tiny hairs left from shaving can also be attributed to dark armpits. Applying lemons to the area, waxing, and skin lightening creams are just a few suggestions to help remedy the problem.