Infection of the cuticle of a nail, which swells up and becomes red and painful. Sometimes pus can be seen through the skin. The disorder can be caused by various bacteria, most commonly by staphylococci and streptococci; they usually reach the cuticle through a small cut or splinter. A small quantity of pus accumulates under the skin, and cannot find an outlet. Pressure increases; it is felt as a throbbing pain. A doctor can release the pus through a small incision in the cuticle, and the condition heals rapidly. If the inflammation is not treated, it will spread, and even lead to the formation of a whitlow. Nail-forming tissue can also be affected, causing the nail to fall off; it will not grow again. A particularly stubborn form of paronychia is caused by the fungus Candida. If this form is not treated rapidly, the nail can be permanently malformed.