Dark underarms, and how to improve them

• Prolonged sun exposure.
• Trauma due to hair removal from shaving or waxes that irritate the skin.
• Transpiration, humidity, and constant friction in the area.
• Some deodorants, perfumes, and other chemicals can generate inflammatory reactions in the armpits with residual dark pigmentation.
• There may be an individual propensity for increased melanin (skin pigment) production in some parts of the body, such as the armpits.
• If you have dark spots in the neck, folds, and joints in addition to the armpits, you should be evaluated by a physician to rule out related metabolic disorders.

Simple Ways to improve dark underarms?

• You should exfoliate once a week.
• It would be best if you regularly change your razor and when shaving, do not shave dry; remember always to use shaving foam. 
• Use SPF equal or higher than 30; you should apply 20 minutes before sun exposure and reapply every 2 hours.
• The use of acid-based compounds for depigmentation is strong and irritating for this area and should be done under dermatological prescription.
• Be careful when trying homemade routines with citrus or homemade mixtures such as lemon since when in contact with the sun, these types of substances can intensify the stains.