Acne is a skin problem that happens when oil and dead skin cells clog your pores. Mild acne may cause just a few red spots, or pimples. Severe acne can cause many pimples on your face, neck, chest, and back, or it can cause bigger, solid, red lumps that are painful and can cause scars.
Mild acne can usually be managed with over-the-counter medicines. But severe acne needs prescription medicines to help clear the skin and prevent scars.