For UVA protection, a sunscreen with a high UVA protection of PA+++ or higher of PA++++ as recommended, especially to treat PIE. PPD is the UVA equivalent of SPF; use a sunscreen with a minimum of PPD20. The PA+ system has a + that corresponds to a tier of PPD protection. Of note, different countries use different PA systems. Japan and Taiwan changed their PA system to a 4+ tier system while Korea uses a 3+ tier system.
Genetics can also have an effect on acne breakouts, and may be the reason some people are acne-prone while others are not. One of the top cited studies took a look at 458 pairs of identical twins and 1099 pairs of fraternal twins to study acne prevalence. They found that genes explained a significant 81 percent of the difference in acne prevalence, while the other 19 percent was explained by non-shared environmental factors. 
If you look in the mirror and see a pimple, don't touch it, squeeze it, or pick at it. This might be hard to do — it can be pretty tempting to try to get rid of a pimple. But when you play around with pimples, you can cause even more inflammation by popping them or opening them up. Plus, the oil from your hands can't help! More important, though, picking at pimples can leave tiny, permanent scars on your face.
Drugs: Some medications may cause or worsen acne, such as those containing iodides, bromides, or oral or injected steroids (either the medically prescribed prednisone [Deltasone, Orasone, Prednicen-M, Liquid Pred] or the steroids that bodybuilders or athletes sometimes take). Other drugs that can cause or aggravate acne are anticonvulsant medications and lithium (Eskalith, Lithobid). Most cases of acne, however, are not drug related.
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