prescription ones and non-prescription ones, including Vc. please read:
http://bbs.wenxuecity.com/health/383710.html
you can try this:
银耳富有天然植物性胶质,加上它的滋阴作用,长期服用可以润肤,并有祛除脸部黄褐斑、雀斑的功效;
http://bbs.wenxuecity.com/health/397856.html
do you use 避孕药或避孕环吗?if yes, stop it. they may cause this problem - disturb your hormone.