Underarm whiteners are the same products used to whiten or bleach other areas of the skin. Although most skin discolorations are due to scarring, birthmarks or side effects of medications, underarm darkening is the result of genetics, excessive sweating, shaving, friction from clothing, and the residue of deodorants and antiperspirants.
One of the most effective ways to bleach the skin is with hydrogen peroxide. This bleaching agent is used for a wide range of products from skin and teeth whitening to paper bleaching. The Food and Drug Administration approves of lower strengths of hydrogen peroxide being used on the skin. The Hair-n-Skin Care website recommends hydrogen peroxide to fade or bleach discolored underarms. Apply hydrogen peroxide with a cotton ball and leave on the skin once a day.
According to Beauty Brain website, “According to at least one dermatologist, dark spots under your arms are the result of dead skin cells that are trapped in microscopic 'hills and valleys' on your skin.” Lactic acid is especially effective for exfoliating or removing the top skin layer which includes dead skin cells and the remains of deodorants. Sources of lactic acid include milk, buttermilk and yogurt. Apply milk or buttermilk to the underarms with a cotton ball. Leave on for 10 minutes then rinse off with warm water. Do this once or twice a day. Frequent exfoliation will prevent the buildup of dead skin cells.
"A simple yet effective solution in treating dark underarms is to rub fresh lemons on the areas,” according to the Hosia Online website. Slice a lemon and rub it on the underarm area. Also buy lemon juice from the store and apply it with a cotton ball a few times each day. Do not rinse off.
Glycolic acid is another alpha hydroxy acid like lactic acid. This acid is also used for exfoliating the skin and removing dark marks. The RN Guide to Skin Care website says that glycolic acid is useful for many skin problems including acne scars, age spots and other problems that discolor the skin. Buy glycolic acid in concentrations of 10 percent to 20 percent if you are new to using this acid. Apply to the skin, leave on for a minute or two, then rinse off. As the skin gets uses to the acid you can leave the acid on for longer periods of time.