The Medical Minute: Treating cuts and bruises

August 18, 2004

By John Messmer
Penn State Milton S. Hershey Medical Center

Everyone has had cuts, scrapes and bruises. As common as these injuries are, everyone should understand how to treat them, but there are numerous common misconceptions about first aid. Should you use alcohol or peroxide? Leave blisters intact or rupture them? Cover it or not? This article contains a look at the basic principles involved in assessing and treating cuts and bruises.


A bruise occurs when tiny blood vessels called capillaries break, but the skin remains intact. If available, ice or a cold pack on the injured area for 10-15 minutes at a time over an hour or two will constrict the capillaries and limit the bruising and swelling. Even individuals on anticoagulants can limit a bruise this way. Ice may be continued if the area is still painful. A physician should be consulted within 24 hours for larger bruises, especially of the face, a bruise near the eye affecting vision, or if the swelling limits the use of a joint.

Some people seem to bruise easily. When bruises are small (smaller than the size of a quarter) and limited to a few areas on the body, they usually are not serious. The skin of older people has lost its supporting tissue and is more easily traumatized. Superficial bruises measuring a couple inches in diameter occur with minimal trauma, particularly on the arms. These do not require special treatment unless the skin is broken.

Large areas of blue or purple discoloration or swelling appearing for no apparent reason should prompt a call to the doctor. Those on anticoagulants may bruise more easily, but large bruises may result from too much anticoagulant medication.

Cuts and scrapes

When the skin is broken, bacteria enter and can cause infection, and bleeding can be more severe. If the wound is large or deep enough, it may take longer to heal and may interfere with the use of the area. These wounds should be treated by a physician.

The first treatment you should provide to any wound is to apply pressure directly onto the bleeding site. While a clean or sterile cloth would be ideal, you can use your bare hand if dressings are not readily available. If bleeding is brisk and particularly if it is squirting out, direct pressure is essential. Do not allow the wound to bleed to clean it out. Bleeding does not cleanse a wound.

Wash the area with soap and water, even if it is still bleeding a bit. Regular soap is fine. You do not need antiseptic soap. The point is to wash away dirt and bacteria. Do not use peroxide, alcohol or bleach -- they will damage the healthy skin and increase the risk of infection. Peroxide is used to clean drainage from infected wounds and abscesses but has no use in cleaning a fresh wound. If dirt, a splinter or foreign material such as road grit is in the wound, tweezers may be needed. Any remaining foreign material impairs healing and increases the risk of infection. If you cannot completely clean it, call a physician.

If bleeding has not stopped by the time the wound is clean or if it resumes, apply direct pressure again with clean gauze or a clean cloth. Five minutes of pressure should stop the bleeding. If not, contact a physician. If bleeding is stopped and the wound is cleaned and covered with a sterile dressing, but you think it requires medical attention, call a physician. After hours, a properly cleaned wound can usually wait until morning for your regular doctor to treat it even if you anticipate it might need stitches. Depending on the wound, it can usually be sutured if it is less than 24 hours old.

A physician should evaluate wounds that gape open, are irregular or have large flaps, have visible fat or cross-joints or involve the face or genitals. A wound that has been thoroughly cleaned and is free of foreign material should not need antiseptic. Mercurochrome, merthiolate and tincture of iodine are toxic to healthy tissue and should not be used.

There is disagreement as to whether antiseptic ointments have benefit. Healing is better when there is just the right amount of moisture -- too much and infection is more likely. A simple straight cut that has been cleaned and covered probably does not need antiseptic ointments. Because an abrasion has a larger area to grow new skin, it might heal better with a thin layer of antibiotic ointment. Recently liquid bandages have become available. These dry to provide a protective coating to maintain proper moisture and should not be applied over an ointment.

As a wound is healing, wash it daily unless your doctor tells you otherwise. If a cut or scrape gets progressively more swollen or painful, gets very red or drains pus, it may be infected and should be seen by a doctor.

Other common injuries

If there is a blister, do not open it. Intact skin provides the best dressing for any type of blister. Once you break it, you invite bacteria inside. If it does break on its own, treat it like a scrape.

Rust does not cause tetanus. Tetanus germs live in the soil, so for puncture wounds or those contaminated with soil, a tetanus booster is needed if it has been five years since the last tetanus shot; otherwise, 10 years is the usual interval for a booster.

With the exception of most bug bites, all bites should be seen by a doctor, particularly human bites or any bite on the hand or fingers. These usually require antibiotics prophylactically.

Cuts contaminated with someone else's blood should prompt a medical evaluation. Diabetics or anyone with poor circulation with cuts or scrapes on the feet may follow the above advice but should see his or her doctor within a day or two of the injury for an evaluation.

Stock your home first-aid kit with a small bar of soap, a variety of adhesive bandages, some sterile gauze, tape, scissors and a small tube of antibiotic ointment. Self-activating ice packs are also a handy item, as are butterfly closures. Preparation now can save time and anxiety later.

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Last Updated March 19, 2009