Friction can be a cause of
hyperpigmentation in the underarms . Another reason could be a skin condition called acanthosis nigricans .

What are the causes of acanthosis nigricans ??

+ Obesity
+ Hormonal imbalances
+ Type 2 Diabetes
+ Side effects of medications

What can you do for this ??

+ Treating the medical condition behind your dark underarms will help .
+ You can also try kojic or glycolic acid .

Remember - Although dark underarms are usually harmless , speak to a doctor to rule out any underlying medical condition .