An open or closed skin pore or hair follicle clogged with oil, dead skin cells, and bacteria. An open comedo is called a blackhead. A closed one is a whitehead.

Self-care options include acne products available without a prescription. These help dry excess oil and promote peeling. A gentle cleanser and oil-free moisturizer also may help.

Seek emergency help if:

• A skin care product causes faintness, difficulty breathing, tightness of the throat, or swelling of the eyes, face, lips, or tongue.

See a healthcare professional if:

• Home care remedies don't clear up comedos.