Retinol
$3.49
While it takes several weeks to see results, retinol is the most effective over-the-counter anti-aging ingredient when it comes to “smoothing wrinkles, unclogging pores, lightening superficial brown spots, and improving the texture of the skin,” [13] Because of retinol’s potency, skin irritation is common, especially in direct sunlight. Apply retinol-based products at night on dry skin to avoid sensitivity and be sure to apply a moisturizer with SPF every morning.