Penis pimples, or more specifically, penile acne pustules, are entirely harmless.It is normal sometimes areas such as these may become infected. Pimples on penis are pretty much the same as pimples on your face, depends what causes them, bacteria or infection. That could only causes irritation, makes them larger or some other problems. STD is not likely applicable to your son s age. Remember just it is important to see your doctor if the pimples change color or gives more pain which you did not mention. Regardless of the severity of your penile pimples you want them gone, cleared up completely, never to come back. Treatment: Washing Wash the area at least twice per day using an acne cleanser. Stop using your regular bar soap or body wash on the area in the shower. Drying Gently pat dry the area with a clean towel. Apply a salicylic acid based acne treatment product to the area. Spread an acne moisturizer over the area. Hope that helps you.