Acne starts when oil and dead skin cells clog the skin’s pores. If germs get into the pores, the result can be swelling, redness, and pus. For most people, acne starts during the teen years. This is because hormone changes after puberty make the skin oilier.

Atopic dermatitis is a long-lasting skin problem. It causes dry skin, intense itching, and then a red, raised rash. In severe cases, the rash forms clear, fluid-filled blisters. It cannot be spread from person to person.