Dr. Mona Gohara's Nighttime Skin-Care Routine "I only use Obagi Professional-C Serum 20% ($127) in the summer both morning and night. I double up on antioxidant in the summer because I'm spending more time outdoors in contact with UV light and the free radicals it produces. Lastly, I put on a light lotion to moisturise." Image Source: dermstore.com Obagi Professional-C Serum 20% $127 from dermstore.com Buy Now