Hello SmileZ

If you do a simple search on this beauty and health topic...you are going to find a zillion remedies. 

It seems the causes are varied from your deoderant, shaving, sweat and friction, to using chemicals to remove hair. 

Some people suggest exfoliation can help or switching deoderants, finding a new way to remove hair under the arms, using a skin whitening agent, or lightening the skin through a mixture of items found in your kitchen or pantry. 

I have no idea which method is going to work best for you so my best advice is to do some research and try one of the methods suggested. 

Here is an eHow article to get you started.

Thank you for your question and let us know if you find something that works for you!