How To Treat Dark Patches On Face,nose And Cheeks?

Hi, My Iam from bangalore, Iam 27 years old and while I notice their are dark patches developing on my face on my nose, chick and these patches are spreading slowly to other parts of my face. I would like to know if I will have go in for consultation with a doctor or their is any face cream I can apply without consulting a doctor.. Kindly revert