Infection can develop after an injury or wound to the skin, such as a cat or human bite or a sting, a tattoo or piercing, or other skin problems. Signs of infection may include:

• Increased pain, swelling, redness, or warmth around the affected area.
• Red streaks extending from the affected area.
• Drainage of pus from the area.
• Swollen lymph nodes in the armpit or neck.
• Fever.

Inflammation develops as a normal protective response of the immune system when body tissue is irritated. When tissue is irritated, the immune system increases blood flow to the area. This causes localized swelling, warmth, and redness. The swelling may put pressure on nerve endings which may cause pain in the area. Inflammation may occur in joints or extremities. Inflammation may occur with overuse of a body area or with minor injuries. Symptoms of inflammation may be present in conditions such as bursitis, arthritis, or tendinitis.

Pain, redness, and swelling that occur with red streaking, heat, fever, or puslike drainage can be caused by an infection. An infection often causes tenderness to the touch or pain with movement at the site of the infection. The redness and swelling of an infection often "spreads" and tends to move toward the center of the body.

Infections can occur without an injury, but most infections develop when bacteria enter the cut, punctured, or scraped skin after an injury.

Types of infection that might affect the fingers, hand, or wrist include:

• Infection of the nail bed margin (paronychia).
• Skin infection (cellulitis).
• An abscess under the surface of the skin or deep in tissue. An abscess at the end of a finger is know as a felon and is usually caused by an infected puncture wound.
• Joint infection (infectious arthritis).
• Bone infection (osteomyelitis).
• Flexor tendon sheath infection (septic tenosynovitis).

People who have conditions such as diabetes, peripheral arterial disease, or immune system problems have a greater risk of developing an infection and complications from an infection.

Mild inflammation or minor infections usually will clear up with home treatment.

Prompt medical treatment of a serious infection can prevent complications.