Discolored skin generally doesn't cause any health issues, but it can be unsightly and embarrassing. Certain antiperspirants can darken the skin, and shaving can leave the appearance of darkened skin as well. Determine what's causing the problem, and consider using one of the methods below to help lighten your armpits and the skin between your thighs to match the rest of your body.
Wax the underarm area. Darker skin around the armpits can be caused by ingrown hairs just beneath the surface. Shaving tends to exacerbate this condition. To save money, you may want to waxing your armpits at home. Be careful and make sure to follow the directions on your home waxing kit to avoid harm.
Get your inner thighs waxed as well. This can be a sensitive and embarrassing area, but it can be dangerous to do at home so it is best to have a professional wax between the thighs.
Tweeze the underarms or inner thighs, if you cannot afford regular waxing. Tweezing can be a time-staking process, but it removes hair at the root and thus helps avoid the darkened skin affect associated with shaving.
Bathe and clean the areas every day, and make sure to dry them fully afterwards.
Exfoliate both areas regularly. Consider using a salt or sugar scrub, or purchase a loofah or other product to exfoliate the skin, as this can help lessen the appearance of discolored and darker skin as well.
Check to see that your deodorant is causing the issue. If the problem is caused by deodorant, it may only be present in the under-arm region rather than between the thighs. If this is between the case, try switching to a deodorant developed for sensitive skin.
Talk to a dermatologist if none of the above methods help. They may be able to provide a skin bleaching cream.