For underarm whitening, we suggest laser toning, 

However, we would like you to understand that pigmentation issues require at least several sessions to see the effects and there is no one-off treatment that could fix all the problems. It really depends on the condition of skin of the patient to decide the treatment plan. That's why we highly recommend that you come in for the consultation with the doctor first.

For details, please refer to this link:

https://bkken.rnmeskin.com/clinic3/bodywhitening.php