Introduction

Corns develop when an area of skin is repeatedly exposed to pressure or rubbing over a long period of time. They mainly occur on your toes and on the soles of your feet. An area of thickened skin (a callus) forms at first. If it continues being exposed to pressure or rubbing, it may develop into a painful corn.

The medical term for a corn is clavus. Corns usually go away on their own if the rubbing and pressure stops – for instance, if you start wearing shoes that fit you better. Soaking the hard skin in warm water can make it softer and easier to remove carefully.

Symptoms

Corns are often painful, particularly when standing and walking. The middle of these round, wart-like lumps of hard skin is usually especially painful. You can normally see a clearly defined core there.

Corns are usually quite easy to see due to their raised surface and the yellowish-beige color of their hard skin. Those that occur between the toes are often whitish in color and softer than those on other parts of the feet. This is because the skin is more moist there.

Typical location and appearance of corns

Causes and risk factors

Corns develop through constant or repeated pressure and rubbing on an area of skin. This causes cells in the outer layer of skin (the epidermis) to divide and grow more than usual. As a result, the skin becomes thicker and has more keratin in it. A round or oval area of hard skin (a callus) develops there over time.

Areas of skin that are close to a bone are particularly likely to be exposed to rubbing and pressure. That’s why calluses and corns are more common on hands and feet than on areas like the belly or thighs. The skin on your hands and feet is more likely to be exposed to pressure or rubbing during everyday activities too – for instance, due to using tools, sports equipment or musical instruments with your hands. Calluses and corns on your feet are usually caused by wearing shoes that are too tight.

People who have a joint disease or a foot deformity are also more likely to have corns on their feet because the ball of the affected foot has to carry more weight. Toe deformities can push the toes against each other or cause them to constantly rub against the inside of the shoes. Pressure and rubbing is more likely to lead to calluses and corns if you have dry skin. Some people are unable to feel their legs and feet properly due to a medical problem affecting their nerves. They often don’t notice calluses or corns developing at first. So it’s particularly important for them to check their feet and legs regularly.

Prevalence and outlook

Corns are very common, particularly in older people.

If the affected area of skin continues being exposed to pressure or rubbing, corns may become thicker and harder. The growing lump of hard skin then puts pressure on the tissue too. As a result, more and more hard skin grows in the middle of the corn. This dense tissue digs into deeper layers of skin like a thorn, which makes the pain worse and causes a chronic inflammation.

Sometimes blood vessels and nerve fibers grow into the edges of the corn. This can also make it hurt more.

Diagnosis

Corns are usually easy to recognize just by looking at them. If the lump of hard skin is in a place that’s regularly exposed to pressure or rubbing, it’s very likely to be a corn.

Although corns are sometimes mistaken for similar lumps such as warts, it’s easy to tell the difference between them based on their appearance. Plantar warts (verrucas), for instance, don’t have a visible core of dense hard skin at the center of the lump. Instead, they often have brownish dots on them. If it’s still not clear whether it’s a wart or a corn, the doctor can take a skin sample which is then examined.

It is easy to tell the difference between a corn and a plantar wart (verruca)

Treatment

In order to treat corns effectively, the most important thing is to reduce the pressure and rubbing that caused them in the first place. For instance, simply replacing tight shoes with wider, well-fitting shoes is often enough to get rid of corns on your feet. You can also use things like small stick-on, ring-shaped corn pads to prevent pressure and rubbing in that area. It’s sometimes a good idea to use insoles in your shoes too. These can correct the position of your toes or feet, reducing pressure and rubbing in the affected area.

If the pressure and rubbing stop, corns usually go away on their own after a while. There are things you can do to try to make them go away quicker, such as regularly soaking your feet or hands in warm water and then carefully removing some of the hard skin – for instance, using a pumice stone. Due to the risk of injury, you shouldn’t use tools with sharp edges, like sharp knives, callus shavers or razor blades. People who don’t have any other skin problems can try to remove the excess hard skin with things like creams or special patches containing urea or salicylic acid.

Some people have a higher risk of injury and wound-healing problems on their feet, for instance due to diabetes. They should avoid trying to treat corns themselves, and instead seek help from a professional such as a foot specialist (a podiatrist).

Further information

When people are ill or need medical advice, they usually go to see their family doctor first. Read about how to find the right doctor, how to prepare for the appointment and what to remember.

Sources

• Knörzer W, Birkner G. Hühneraugen. In: Ruck H (Ed). Handbuch für die medizinische Fußpflege - Grundlagen und Praxis der Podologie. Stuttgart: Haug; 2012.
• Moll I. Duale Reihe Dermatologie. Stuttgart: Thieme; 2016.
• Pschyrembel. Klinisches Wörterbuch. Berlin: De Gruyter; 2017.
• Rodriguez-Sanz D, Tovaruela-Carrion N, Lopez-Lopez D, Palomo-Lopez P, Romero-Morales C, Navarro-Flores E et al. Foot disorders in the elderly: A mini-review. Dis Mon 2018; 64(3): 64-91. [PubMed: 28826743]

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