Thanks for writing in.
You seem to have melasma
For pigmentation as a general rule-
Avoid sun exposure
Use a good sunscreen of SPF 30 and repeat application every 3 to 4 hours
Take antioxidant and vitamin c
contains steroid and can damage your skin in long term.Better avoid it.
You can apply Depiwhite cream at night time over the affected area.
You need to consult a dermatologist
as dermatology being a visual field
, the cause for your pigmentation and the treatment required can only be suggested after proper skin examination.
Treatments like chemical peeling will be very helpful.Discuss these option with your dermatologist.