To treat tanning over your face, you might try these suggestions
Use a mild Glycolic acid
based face wash like Aha glower melawash
Use a good sunscreen of SPF more than 30 like shadowz, photoban etc
Take vitamin c
and oral antioxidant supplements
Apply Kojic acid
based cream in morning like kojivit or clearz plus and a Glycolic acid 6 percent cream in night. With in a month or two, you will notice good response.
I would advise you to take few sessions of chemical peels
too for better response
Hope that answers your query. Take care.