Cuts or tears in tissue (lacerations), scrapes (abrasions), and puncture wounds can be caused by bites or by other mechanisms. Wounds that are not caused by bites and are clean and relatively small usually heal rapidly without any problems. However, some wounds can cause extensive blood loss.
In some wounds, deeper structures, such as nerves, tendons, or blood vessels, are also injured. Other wounds can become infected. A piece of foreign material (such as a splinter, glass, or a clothing fragment) can also remain hidden inside a wound, causing later problems such as infection.
Shallow cuts to most areas of the skin rarely bleed much and often stop bleeding on their own. Cuts to the hand and scalp as well as cuts to arteries and larger veins often bleed vigorously.
Infection can develop when a wound is contaminated with dirt and bacteria. Although any wound can become infected, infection is particularly likely in deep scrapes, which grind dirt into the skin, and in puncture wounds (particularly those resulting from animal bites or human bites), which introduce contamination deep under the skin. Also, wounds that contain foreign material frequently become infected. The longer a wound remains contaminated, the more likely it is that infection will develop.
Wounds can be painful at first, but usually the pain lessens after the first day. If a cut affects a nerve or tendon, the person may be unable to move the body part fully. Some nerve injuries cause weakness or paralysis, loss of sensation, or numbness. If foreign material remains inside a puncture wound, the part of the wound near the material is usually painful when touched.
Pain that worsens a day or more after the injury is often the first sign of infection. Later, an infected wound may become red and swollen and may ooze pus. A fever may also develop.
Necrotizing skin infections are rapidly progressing infections that threaten life and limb that can occur even after a very minor skin wound.
