Yogurt seems to be a useful home remedy for many different ailments, and that includes the treatment of dark underarms. Although the condition is not dangerous, nor technically a disease of any kind, it can be unsightly or a sign of embarrassment, and can also lead to other more serious conditions. If you apply yogurt to your dark underarms, the minerals and compounds in yogurt can effectively lighten the skin color and eliminate any damage to the skin that might be causing the color change. Spread yogurt under each armpit and let it sit for 20-30 minutes; the effects should be quick and satisfying!