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Corns

Published by Bupa's health information team, December 2008.

This factsheet is for people who have corns, or who would like more information about them.

A corn is a painful area of hardened skin on the foot. They develop over bony areas of the foot that are under high pressure, usually caused by poorly fitting shoes.

Corns can be treated with pads to cushion the affected area, with pumice stones to rub them away, with medicines to break them down, and by getting better-fitting footwear.

As well as ill-fitting shoes, corns can sometimes be a sign of problems with the way your feet bear your weight. In rare cases surgery might be needed to correct these problems.

• About corns
• Symptoms of corns
• Complications of corns
• Causes of corns
• Diagnosis of corns
• Treatment of corns
• Further information
• Questions and answers
• Related topics
• Sources

About corns

Corns develop on your feet in response to sustained pressure, usually from shoes that don't fit.

A corn is a type of painful callus on your foot.

A callus is an area of hardened skin made of keratin - a tough protein that makes up hair and nails but which is also present in the outermost layer of skin (the epidermis). When skin is exposed to lots of pressure or friction, the keratin layer thickens to protect it, and develops into a callus. Calluses aren't painful, and can cover a wide area.

However, if the pressure is over a bony protrusion, a small hard plug of keratin can form that presses into the skin, sometimes causing pain and swelling. This is a corn. It can be very painful as the keratin plug may put pressure on underlying nerves.

Unlike calluses, corns are clearly separate from the surrounding area of skin. In the middle of them is a see-through plug of keratin which is surrounded by a clear whitish margin of tough skin.

There are two main types of corn.

Hard corns

Hard corns are the most common type of corn. They are concentrated areas of dry hardened skin about the size of a pea. They may occur within a broader area of callused skin. They often occur on toes, most commonly the fifth toe. They are sometimes called digital corns.

Soft corns

Soft corns are extremely painful. They tend to develop between toes. They are like hard corns that have been softened by continual exposure to moisture from sweat. Soft corns sometimes become infected by bacteria or fungi.

There are other rarer types of corn.

• Seed corns. These are clusters of small corns on the bottom the foot. They are usually painless.
• Vascular corns. These occur on blood vessels and bleed if cut.
• Fibrous corns. These are corns that have been present for a long time and have become attached to deeper layers of the skin.

Symptoms of corns

The main symptom of a corn is pain when you walk. This pain may stop you from doing some activities. You will see a lump of hard skin over a bony area.

Complications of corns

If a corn is left untreated, it can ulcerate. This means an open sore will form on it. This is especially a problem if you have diabetes or are elderly as it may become infected and/or heal poorly, because of bad circulation. See your GP, podiatrist or chiropodist immediately if you have diabetes or are elderly and notice any broken skin, loss of sensation or bruising on your feet.

Causes of corns

Corns are caused by constant pressure on a bony area of the foot. This can happen because of a number of different reasons. Some examples are listed below.

• Poorly fitting footwear. Shoes that are too small, or that have irregular soles, are the most common cause of corns.
• Being very active. People who do lots of exercise, such as athletes, put more pressure on their feet, and this can make corns more likely to form.
• Prominent bones. In some people, prominent bones in your feet can press against your shoes. This can lead to corns.
• Misshapen foot. Sometimes your foot or toes may have developed unusually - for example a toe may be overly curved, or a particular bone too short. This may cause your foot to press against your shoes and this can cause corns.
• Poorly healed fractures. If you have broken a toe or another bone in your foot, it may set out of place. This can cause your foot to press against your shoes leading to a corn.

Diagnosis of corns

If you are getting persistent foot pain, go and talk to your GP about it. He or she will examine your foot to look for any signs of calluses or corns. Your GP will also ask you about your footwear and whether you have had any previous treatment or surgery on your feet.

Corns can be confused with verruccae. To distinguish between them, your GP may use a scalpel to slice off the top layer of hardened skin (this isn't painful) to look for blood vessels that would be present in a verruca.

You GP may refer you to a registered chiropodist/podiatrist (healthcare professionals who deal with problems with the foot).

If it's a serious problem, or if it keeps coming back, the healthcare professional might recommend an X-ray to help identify how and why a bone is causing a corn. He or she may also recommend a pedobarograph, which can be used to examine foot pressure patterns.

Treatment of corns

Because corns are a sign of pressure on your feet, the underlying cause needs to be addressed in order to stop them coming back. There are several ways that corns are treated. Don't try and cut out a corn by yourself, especially if you are elderly or diabetic.

Self-help

You might be able to relieve some corns yourself. However, don't use corn plasters or paints that you can buy unless your doctor or a registered chiropodist or podiatrist has recommended them. They contain chemicals that can burn healthy skin. You also shouldn't try and cut the corn out yourself. This is especially true if you are elderly or diabetic (see Complications).

Instead, use a pumice stone to rub away the thickened skin, a little at a time. This is best done after you have soaked it in the bath for about 20 minutes so it is softer. If the corn is between your toes, you can purchase foam wedges that will relieve the pressure.

If you aren't sure how to go about tending to a corn, go and see your GP or a registered chiropodist or podiatrist.

Minor surgery

The centre of a corn may press onto the nerves under your skin causing intense pain. Your GP or a registered chiropodist or podiatrist will be able to use a scalpel to remove the central keratin plug from a corn. This will almost completely relieve the pain.

Your doctor or health professional will also advise you to gently rub away the corn using a pumice stone (see self-help) every week to help prevent it coming back.

Medicines

Your GP or podiatrist/chiropodist may apply a paint that can break down the keratin in a corn and soften it. However these can burn surrounding areas of skin so aren't always used. They can be bought over the counter but because of the risk of burning healthy skin, don't use them unless your healthcare professional recommends them to you.

Footwear

The main cause of calluses and corns are tight shoes. These need to be replaced otherwise the corns will come back. Your healthcare professional will advise you on what type of shoes to wear. They should have a soft upper half, have low heels and lots of room for your toes.

If you have a corn between your toes or on the outer edge of your fifth toe, your shoes may need to have extra width to give more room.

Foot pads

Your health professional might recommend using foot pads or insoles to relieve the pressure on your feet and stop the corn from redeveloping. He or she will be able to help advise you what to use and how to fit it.

Surgery

If the corn keeps coming back, and all other methods have failed to solve the problem, surgery might be able to help in some cases. Surgery is especially useful if a deformed toe is causing a corn.

Surgery to remove bony prominences can also prevent corns in some circumstances.

Other types of surgery to correct different types of foot deformities can also help prevent corns. Your GP or health care specialist will be able to advise you on whether surgery is necessary.

Further information

• The Society of Chiropodists and Podiatrist
  020 7234 8620
  www.feetforlife.org

Related topics

• Warts and veruccas
• Fungal skin infections

Sources

• Simon C, Everitt H, and Kendrick T. Oxford Handbook of General Practice. 2nd ed. Oxford: Oxford University Press, 2005:648-649
• Corns. GP Notebook. www.gpnotebook.co.uk, accessed 12 June 2008
• Corns. The Society of Chiropodists and Podiatrists. www.feetforlife.org, accessed 12 June 2008
• Singh D, Bentley G, and Trevino SG. Fortnightly Review: Callosities, corns, and calluses. BMJ 1996; 312(7043):1403-1406. www.bmj.com, accessed 1 January 2008
• Footcare for people with diabetes. The Society of Chiropodists and Podiatrists. www.feetforlife.org, accessed 12 June 2008

This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.

Publication date: December 2008