First of all remove underarm hair. Your underarms can look dark because of the ingrown hair under skin. You can clear it by waxing but avoid shaving as shaving only removes the hair above skin and creates an illusion of darkness.
* Apply some skin lightening creams. Buy some good quality skin lightening products like scrubs that contain peptides and various natural extracts that help in removing the darkness of armpits. These scrubs should be used twice per week for removal of dirt and dead skin cells.
* Clean your underarms daily. Wash and clean underarms every day while taking bath. Washing it every day can make skin dry, and hence remember to moisturize it.
* Use aloe vera gel that can be used as a natural exfoliating product. Apply the aloe vera gel under your arms. This gel provides antioxidants and moisture that helps to clean our pits and make it soft.
* Potatoes are rich in a natural skin lightening enzyme called catecholase. This enzyme is very helpful in removing dark spots, scars and lightening dark skin. Take a potato and cut a thick slice from it. Rub this slice to your armpits for 15 minutes and then wash it. Repeat it daily for getting positive and more effective results.
* Avoid wearing tight clothes. This can also be a reason for bad underarm condition. When tight clothes rub to your armpits, it leads to skin darkening in that area. Hence, to reverse this problem, wear comfortable clothes.
* Do not use low quality or very strong deodorants as it can make underarms appear black. These products contain harmful chemicals which cause skin pigmentation. Hence, use the best quality product that is chemical and problem free.
Not exfoliating skin and lack of moisture leads to dead cell accumulation under armpits, which makes it appear dark and dull. Proper care of skin is the only fast way to get rid of dark underarms.