DEAR DOCTOR K: I have an open sore on the bottom of my foot. Can I just cover it with a Band-Aid until it heals, or do I need to see a doctor?
DEAR READER: I am glad you asked this question, because in most circumstances, just covering it with a Band-Aid is a really bad idea.
I’m guessing that this “sore” is more than some redness of the skin. I assume it is a little hole or crater, and that the top skin of the sole of your foot is gone. If that’s the case, what you’ve got is called a foot ulcer. A foot ulcer crater is often surrounded by a border of thickened, callused skin. (I’ve put an illustration on my website, AskDoctorK.com.) Some craters are shallow. In severe ulcers, the red crater may be deep enough to expose tendons or bones. If you have a foot ulcer, you should see your doctor.
People with diabetes are more likely to get severe foot ulcers. That’s because diabetes can cause nerve damage in the feet, which makes them less sensitive to pain or discomfort. People with diabetes can injure their foot significantly and not know it because they experience no pain. As a result, the ulcer can slowly get worse.
People with diabetes are at special risk from having a foot ulcer. Because diabetics often have poor blood supply in their feet, their foot ulcers have more trouble healing. Healing requires a good blood supply to provide energy and a steady flow of immune system cells to do its work.
Foot ulcers are vulnerable to infection. An untreated infection can develop into:
— An abscess, or pus-filled pocket;
— A spreading infection of the skin and underlying fat;
— A bone infection;
— Gangrene, an area of dead, darkened body tissue.
If you have good circulation, your doctor can treat your foot ulcer by trimming away diseased tissue and removing any nearby callused skin. The doctor will apply a dressing and may prescribe specialized footwear to relieve pressure on the affected area. If there is a possibility of infection, you may need to take antibiotics.
Foot ulcers that do not respond to more conservative therapy may require surgery. If you have poor circulation, you may need surgery to correct blood-flow problems in your leg arteries. And if the circulation is poor enough, there may be no way to cure a foot ulcer, and the recurrent infections that develop in that ulcer, except by amputating the foot.
So if you’ve had one foot ulcer, you should see your doctor about it. After the ulcer is cured, you should take steps to help prevent future ulcers:
— Examine your feet every day to check for rubbed areas, cracks or calluses.
— Wash your feet every day using mild soap and warm water. Dry thoroughly. Apply moisturizing lotion to dry areas. — Wear roomy, well-cushioned shoes and soft, absorbent socks.
Dr. Anthony L. Komaroff is a physician and professor at Harvard Medical School. To send questions, go to AskDoctorK.com, or write: Ask Doctor K, 10 Shattuck St., Second Floor, Boston, MA 02115.