Though rarely serious, fingernail infections are very common and painful, and occur on or near the edge of the nail, where it meets the skin of the finger. Bacteria can enter the skin around the nail and cause an infection. Nail-biting and ingrown fingernails are the primary cause of fingernail infections, and they are also common to occur in children from finger sucking. Some kind of trauma to the fingernail area are common reasons bacteria can enter the skin, like from an injury or cut, or an animal or insect bite. Each of the most common types of fingernail infections have specific symptoms and signs of infection that require proper evaluation. Paronychia – Infected area next to the fingernail will be red and swollen with visible pus seen under the skin. Tender and painful to the touch, the infected area may also leak a white-yellow and cloudy fluid. Felon – The fingertip will be swollen and painful. Swelling in the pad of the finger develops over several days. The area might be red with a visible collection of pus under the skin. Herpetic Whitlow – Red and tender fingertip, possible burning and itching feeling with mild swelling (not as much as a felon). A single, or several open wounds may be visible in the infected area, which form in clusters after the formation of small blister-like lesions. Fluid in lesions will be clear or slightly cloudy. Infections may also cause low-grade fever and swollen, tender lymph nodes. Cellulitis – Usually superficial infections without involving deep structures. The area will be red, slightly swollen, tender, and warm to the touch. Usually not painful but will cause restriction of finger use. If pain is present, it may indicate a deep space infection.  Infectious Flexor Tenosynovitis – The four primary indicators are called Kanavel cardinal signs: 1. Tenderness over the flexor or palm side of a finger, and pain over the tendons in the finger; 2. Uniform swelling of the finger; 3. Pain while straightening out the finger; 4. The finger is held in a slightly bent or partially flexed position. Deep Space Infections – Occurs as pain and swelling in the web of the fingers, also called a collar button abscess, and maybe red and warm to touch. As the abscess grows larger, the fingers will begin to spread apart slightly by the increasing pressure.