“If the plugged follicle, or comedo, stays beneath the skin, it is called a closed comedo and produces a white bump called a whitehead.”

“If the opening of the skin pore is sealed off from air, the result is a whitehead.”

“If a blackhead or whitehead becomes inflamed, a raised, red pimple develops.”

“These pimples vary according to the severity of the acne and range from whiteheads, blackheads, pustules and nodules to cysts.”

“Differin is very effective for treating blackheads and whiteheads, and even some cystic acne.”

“Most people have noninflammatory acne, a relatively mild form with just a few whiteheads and blackheads.”