<prompt> Substance used a bleaching agent in melasma is ?HydroquinoneHydroxychloroquinHydrogen peroxideBenzoyl peroxide  <response>: Ans. isa i.e., Hydroquinone Ref : IADVL textbook of dermatology 3d e p. 1607 Depigmenting agents Bleaching agents:Hydroquinone 2-5Ascorbic acidRetinoidsLiquorice extractAzelaic acid 10-20Kozic acid 1-4ArbutinNicotinamide 