The lemon works as a bleaching agent, to cover blotches.

The home remedy is as follows:
You require lemon juice of 1/2 a lemon and 1 egg white, beaten.  Mix the ingredients together and apply on the affected area. Leave overnight for best results. If you need immediate result, apply the mixture for 12-15 minutes, and spray warm water on your face to rinse.
Blend 1 apple and 1tbsp honey in a blender/processor; make a fine smooth paste (drain). Apply to face and leave for 15 min. then rinse.