Hello and welcome to healthcaremagic. Indian skin is type IV skin (Wheatish) which contains good amount of melanin, therefore is prone to tanning even on moderate sun exposure. Whereas, people in the west have type I or Type II skin which contains very less amount of melanin (White skin), therefore it does nt tan on sun exposure, as much as Indian skin. UV A part of the electromagnetic spectrum is mainly responsible for tanning. Therefore, a good sunscreen should have broad spectrum UV A coverage in addition to UV B coverage, in order to be able to prevent tanning and it needs to be applied in sufficient quantity and every 2-3 hourly. A sunscreen with minimum 30 spf would be adequate. It should mention both UV B and UV A coverage. It should be applied in the following quantity for adequate protection: --3ml for face and neck(a little more than 1/2 teaspoon) --3ml for each arm(a little more than 1/2 teaspoon). A sunscreen should be applied every 2-3 hours. If I was the treating doctor I would have also asked you to use a cream containing one or more of the skin lightening agents e.g kojic acid, glycolic acid, arbutin etc once daily at night to gradually fade away the tan. regards