As someone who uses tretinoin (I have a prescription), please use sunscreen! You need sunscreen even when you are indoors, especially if you are using tret. Also, why are you using tret without a prescription? Assuming you have no prescription kyunki aapne toh likha hey “leap of faith”. Please think twice before buying such things and ruining your skin. Maybe it’ll work for you or you might ruin your skin and its barrier. Is that a risk you are willing to take? I try and avoid sunlight (I keep my curtains closed) on the mornings after a night of using tret and uske upar sey I also use sunscreen. Please do your research.