Is antioxidant serums necessary to keep healthy skin?

Not necessary: The key to healthy skin is avoid sun exposure & smoking. Important skincare includes exfoliation, collagen stimulation & sun protection on a daily basis. Antioxidant serums can help prevent sun damage & skin cancer, & some contribute to collagen stimulation. If you use a vitamin c based serum make sure it is a stable product, otherwise it can accumulate free radicals (the opposite of antioxidant).