This factsheet is for people who have corns, or who would like information about them.
A corn is a painful area of hardened skin on the foot. Corns develop over bony areas of the foot that are under high pressure, usually caused by poorly fitting shoes, or sometimes from the way your feet bear your weight.
- About corns
- Symptoms of corns
- Complications of corns
- Causes of corns
- Diagnosis of corns
- Treatment of corns
- Prevention of corns
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 is found in the outermost layer of your skin (the epidermis).
When your skin is exposed to lots of pressure or friction, the keratin layer thickens to protect it, and develops into a callus. Although calluses can cover a wide area, they aren’t usually painful.
However, if the pressure is over a bony protrusion, a small hard plug of keratin can form that presses into your skin, sometimes causing pain and swelling. This is a corn. It can be very painful as the keratin plug may put pressure on your underlying nerves.
Unlike calluses, corns are clearly separate from the surrounding area of your skin. In the middle of them is a see-through plug of keratin, which is surrounded by a margin of tough skin (often white in colour).
If you develop a corn and you have diabetes, it’s very important that you see your GP because you’re more prone to developing infections. Sometimes a corn can ulcerate – this means it develops into a sore (ulcer) – and may become infected.
Types of corn
There are two main types of corn.
Hard corns are the most common. They are concentrated areas of dry, hardened skin about the size of a pea. Hard corns may develop within a broader area of callused skin. They are often found on your toes, most often on your fifth toe. They are sometimes called digital corns.
Soft corns are white and rubbery. They can be extremely painful and tend to develop between your toes. They are like hard corns that have been softened by continual exposure to moisture, usually because you don’t dry between your toes properly or from sweat. Soft corns may form opposite one another and are known as ‘kissing lesions’.
Sometimes, soft corns can become infected by bacteria or fungi.
Other, rarer types of corn include:
- seed corns – these may appear as one corn or as clusters of small corns on the bottom your foot; they are usually painless
- vascular corns – these occur in your blood vessels and bleed if cut
- fibrous corns – these are corns that have been around for a long time and have become attached to the deeper layers of your skin, sometimes causing pain
Symptoms of corns
The main symptoms include:
- a lump of hard skin over a bony area on your foot
- pain when you walk, sometimes stopping you from doing certain activities
Complications of corns
If your 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 an older person as the sore may become infected and/or not heal very well because of bad circulation. See your GP, podiatrist or chiropodist (health professionals who specialise in conditions that affect the feet) as soon as possible if you have diabetes or are 65 or over and notice any broken skin, loss of sensation or bruising on your feet.
If you have an infected corn, for example if it contains pus or clear liquid, it may need to be drained. You may also need antibiotics.
Causes of corns
Corns are caused by constant pressure on a bony area of your foot. This can happen for a number of different reasons. These include:
- poorly fitting footwear – for example, shoes that are too small, cramp your toes or have uneven soles; this is the most common cause of corns
- being very active – doing lots of exercise can put pressure on your feet
- prominent bones – these can press against your shoes
- a misshapen foot because your foot or toes have developed unusually – you may have a toe that is overly curved or a particular bone that is too short
- poorly healed fractures – if you have broken a toe or another bone in your foot, it may have set out of place causing your foot to press against your shoe
Diagnosis of corns
Your doctor will ask about your symptoms and examine you. He or she may also ask you about your medical history and your footwear.
Corns can be confused with verrucas. Your GP may use a scalpel to remove the top layer of hardened skin (this isn’t painful) to look for blood vessels that would be present in a verruca but aren’t found in a corn.
You GP may refer you to a registered chiropodist or podiatrist.
If your corn is a serious problem or if it keeps coming back, you may have:
- an X-ray – to help identify how and why a bone is causing a corn
- a pedobarograph – a test to look at the pressure patterns of your foot
Treatment of corns
Your healthcare professional will try to deal with the underlying cause of your corn to stop it coming back as well as treating its symptoms.
There are several ways that corns are treated.
Although you should never try to cut out a corn yourself, there are other things you can do to help relieve the symptoms.
- Use a pumice stone to rub away the thickened skin, a little at a time. Do this after you have soaked your foot in the bath for about 20 minutes so that your skin is softer.
- If the corn is between your toes, you can buy foam wedges that may help to relieve the pressure.
If you aren’t sure how to go about tending to a corn, see your GP or a registered chiropodist or podiatrist.
The main cause of corns is wearing shoes that are too small and tight for your feet. You will need to stop wearing any shoes that don’t fit well. Your healthcare professional can advise you on the best type of shoes to wear but in general they should have:
- a soft upper half
- low heels (less than 4cm)
- a round toe that provides lots of room for your toes
If you have a corn between your toes or on the outer edge of your fifth toe, you may need wider shoes to give your feet more room.
Your health professional may recommend using:
- foot pads or insoles to relieve and redistribute the pressure on your feet and stop the corn from coming back
- other corrective made-to-measure foot appliances that can provide long-term relief
He or she will be able to help advise you about what to use and how to fit it.
Your GP or a chiropodist or podiatrist will be able to use a scalpel to remove the central keratin plug from a corn. This is a painless procedure and should almost completely relieve any pain. He or she may also advise you to gently rub away the corn using a pumice stone every week to help prevent it coming back.
If the corn keeps coming back and all other methods have failed to solve the problem, further surgery might be able to help. For example, if your corn is being caused by a deformity on your foot, an operation to reshape your foot can sometimes prevent it returning.
Your GP or healthcare professional will be able to advise you on whether surgery is necessary.
Prevention of corns
You can help prevent corns by:
- wearing sensible, low-heeled footwear (maximum 4cm heel) with a rounded toe
- not wearing slip-on shoes because these cause your feet to move forward and squash your toes
- not wearing court shoes because they don’t support your feet and can cramp your toes
- drying properly between your toes
- losing excess weight – this will help to reduce pressure on your feet
If you already have a corn, apply an antifungal or antibacterial powder after washing your foot to help prevent it becoming infected.