Is your teen applying something to his face that is triggering or worsening his acne? Sunscreens, should be non-comedogenic, hypoallergenic and provide broad spectrum sun protection; good choices from your dermatologist include DermaTopix and SkinMedica sunscreens, and ColoreScience Sunforgettable, a brush-on chemical-free mineral sunscreen that is recommended by the Skin Cancer Foundation. Neutrogena and Aveeno facial sunscreens are available from your drugstore.
Sports helmets and other headgear can also promote acne, by trapping perspiration and blocking pores in the areas of skin that they cover. If your teen is shaving, it's better to wet-shave than to use an electric razor, and to shave only in the direction of hair growth, even though this gives a less close shave than moving the razor in different directions.