I am using apple cider vinegar and onions juice 20 minutes on face every day this is best for pigmentation treatment?

Skin pigmentation: Facial skin pigmentation may be caused by many things. There are forms of inflammatory conditions of the skin that may cause this. Sun avoidance & protection is critical to any treatment regimen. Unfortunately, treatment with apple cider vinegar and onions has not been shown to be effective. An examination & evaluation by a medical provider would be helpful in accurate diagnosis & treatment.

To be honest: Your best bet is to be good about sun-protection, along the lines of SPF 50, and to minimize sun exposure. Otherwise, you be just as likely to suffer a reaction to prolonged exposure. Make sure you are diluting your apple cider vinegar. Remember if you are using it to try to bleach your natural skin color, I would strongly advise against this.