MSD Manual

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Amy H. Kaji

, MD, PhD, Harbor-UCLA Medical Center, David Geffen School of Medicine

Reviewed/Revised Jul 2022 | Modified Jun 2023

Cuts or tears in tissue (lacerations), scrapes (abrasions), and puncture wounds can be caused by bites Introduction to Bites and Stings Many creatures, including humans, bite when frightened or provoked. Others include Alligators and crocodiles Iguanas Mites Ticks read more 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.

Did You Know...

  • Even shallow cuts to the scalp or fingertip may 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 Animal Bites Most animal bites in the United States are from dogs and cats. Wounds should be cleaned and cared for as soon as possible. (See also Introduction to Bites and Stings.) Although any animal may... read more or human bites Human Bites Because human teeth are not particularly sharp, most human bites cause a bruise and only a shallow tear ( laceration), if any. Exceptions are on fleshy appendages, such as the ears, nose, and... read more ), 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.

First-Aid Treatment

The first step in treating a cut is to stop the bleeding. Visible bleeding can almost always be stopped by firmly compressing the bleeding area with a finger or hand for at least 5 minutes. Whenever possible, the bleeding part is elevated above the level of the heart. If the bleeding is on an arm or leg and continues after pressure has been applied, a tourniquet can be applied by anyone who has been trained to use one. This is usually required only in severe injuries (for example, gunshot wounds, deep penetrating stab injuries, large deep cuts, or amputations. Tourniquets should be used only until the person can be evaluated and treated by a doctor. (See Stop the for additional information on tourniquet use.)

To prevent infection, dirt and particles are removed and the wound is washed. Large, visible particles are picked off. Smaller dirt and particles that cannot be seen are removed by washing with mild soap and tap water. Colder temperature water may allow the blood vessels to constrict, helping to slow the bleeding. Dirt and particles that remain after washing often can be removed with a more highly pressured stream of warm tap water. Harsher agents, such as alcohol, iodine, and peroxide, are not recommended. These solutions can damage tissue, impairing the capacity to heal.

Scrubbing is required to clean deep scrapes. If a wound is very small, it can be kept closed with certain commercially available tapes. Stitches may be needed for deep or large cuts. After cleaning and, if necessary, closing the wound, antibiotic ointment and a bandage are applied.

Medical assistance is needed under the following circumstances:

All wounds, whether treated at home or by health care practitioners, should be observed for symptoms of infection (worsening redness, tenderness, warmth, or drainage of pus) during the first several days after treatment. If any symptoms of infection develop, medical assistance should be sought within several hours.

Most small wounds heal within a few days.

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