You've probably heard that applying sunscreen or wearing a daily moisturizer that contains sun protection formula (SPF) 15 or higher is a good idea. It's a skin care tip that will also help reduce acne scars. Even if you do nothing more than prevent future outbreaks, using sunscreen faithfully will keep scars from getting darker; eventually they'll fade. As you may already know, the sun's rays increase the amount of melanin or pigment in the skin. As with tanning, the more your skin is exposed to the sun, the darker it gets. When you have acne scars, they just continue to deepen in color from sunlight -- unless you smooth on a layer of sunblock every day.
The simplest way to get the proper protection is to use moisturizer designed for your particular skin type that has a SPF rating of 15 or greater. The same applies with body lotion if you're dealing with acne on another area of your body like the back, chest or legs.