Hello and welcome to healthcaremagic
Melasma presents as brownish patches of discoloration on face, specially on cheeks, nose, and sometimes also on the
upper lip, forehead etc.
Hormonal pills and pain killers are well known causes of melasma. Pregnancy is commonly associated with melasma. However most of the cases are Idiopathic
I would suggest you to use a broad spectrum sunscreen throughout the day. A sunscreen with minimum 30 SPF would be adequate.
A good and effective sunscreen should have broad spectrum UV A coverage in addition to UV B coverage, and it needs to be applied in sufficient quantity every 2-3 hourly.
It should be applied in the following quantity to have the desired protection: --3ml for face and neck(a little more than 1/2 teaspoon)
A sunscreen marketed by johnsons & johnsons, 'NEUTROGENA DRY TOUCH ULTRASHEER SUNSCREEN' is a good choice and is available OTC.
A cream containing one or more of the skin lightening agents e.g
kojic acid,
hydroquinone,
glycolic acid, undecylenoyl
phenylalanine, arbutin etc can be used once daily at night, to gradually fade away the dark parches.
Regards