Greetings. There are no proven studies to say that oral glutathione causes skin whitening. But there are patients who have taken it, and have noticed a difference. But that's not same with everyone. There are various lasers and peels available to enhance your skin color by one or two shades. Along with the procedures,
vitamin C serum is definitely helpful, not only for pigmentation, but also for skin rejuvenation and as an anti aging cream.
Regards
Dr Shishira