A paronychia is an infection of the skin that surrounds a toenail or fingernail. There are two different types of paronychia, acute and chronic:
Acute paronychia — This usually appears as a sudden, very painful area of swelling, warmth and redness around a fingernail or toenail, usually after an injury to the area. An acute paronychia typically is caused by an infection with bacteria that invade the skin where it was injured. The injury can be caused by overaggressive manicuring (especially cutting or tearing the cuticle, which is the rim of paper-thin skin that outlines the outer margins of your nail). It can also result from biting the edges of the nails or the skin around the nails, picking at the skin near the nails or sucking on the fingers.
Chronic paronychia — This is an infection that usually develops slowly, causing gradual swelling, tenderness and redness of the skin around the nails. It usually is caused by Candida or other species of yeast (fungus). It often affects several fingers on the same hand. People who are more likely to get this infection include those with diabetes or workers whose jobs constantly expose their hands to water or chemical solvents. Such jobs include bartending, house cleaning, janitorial work, dentistry, nursing, food service, dishwashing and hairdressing.