What Is a Callus?

A callus is a change in your skin that forms to protect an area subject to constant strain, friction, or pressure. It appears as a dense, flat area of skin that hardens in an uneven shape. Common sites of a callus are the sides and soles of your feet and the palms of your hands.

This article describes a callus, its types, causes, associated conditions, symptoms, and treatment. It also addresses when to seek medical care for a callus.

Callus Types

There are two basic types of calluses:

• Discrete nucleated callus: A discrete nucleated callus is a localized painful lesion with a central keratin plug. It can sometimes be confused with a plantar wart.
• Diffuse-shearing callus: A diffuse-shearing callus appears as a lesion measuring more than 1 centimeter across. It does not contain a keratin plug.

What Causes a Callus to Form?

A callus occurs as a result of hyperkeratinization. This process involves thickening the stratum corneum, the outer layer of your skin. It is made of a protein called keratin. Keratin helps protect your body against water and other substances.

The process of hyperkeratinization is your skin's response to constant pressure or friction in one spot. It reacts by making extra layers of keratin to protect the stressed spot. The extra layers of skin continue to grow. They can cause discomfort or pain as the skin thickens in one place.

You have a higher risk of developing a callus if you participate in activities that involve repeated friction on the same areas of your hands or feet. A callus is more likely to form as a result of the following tasks and activities:

• Lifting heavy weights
• Using hand tools
• Playing a stringed instrument
• Running long distances
• Playing sports like tennis or basketball, in which you have constant pressure on your feet
• Walking on hard surfaces without shoes
• Kneeling to lay tile or carpet without padding on your knees
• Obesity
• Wearing tight footwear, high heels, or narrow shoes
• Wearing loose shoes that allow the shoe to slide and rub against a seam in the shoe
• Walking with an abnormal gait or weight distribution due to a foot deformity like flat feet

Associated Conditions

Having certain conditions can make you more susceptible to developing calluses. This includes:

• Pachyonychia congenita: A rare genetic disorder that causes defects in the skin and nails. The condition results from mutations that affect keratins, the proteins that help your nails, hair, and skin grow, function, and remain healthy. Thickened nails and painful debilitating calluses on the soles of the feet are common symptoms.
• Diabetes: Having diabetes increases your risk for calluses on your feet. People with diabetes often develop neuropathy, a form of nerve damage that causes the loss of feeling in their feet. As a result, you may not notice that the soles of your feet are dry and cracked, making them susceptible to callus formation. You may also not notice when a callus forms and unknowingly allow it to persist without treatment. Complications can occur if a callus forms and remains untreated because you can't feel it. An untreated callus can eventually become infected and lead to skin ulceration.
• Foot abnormalities: Foot abnormalities like flat feet that create abnormal foot biomechanics can force you to walk with an unnatural gait. This can distribute your body weight in a way that causes abnormal mechanical stresses on your foot in areas not intended to support this type of stress.
  

What Are the Symptoms of a Callus?

A callus usually appears rough and dull. It can be raised, though it is usually flat in an irregular shape. A callus can develop the following symptoms in the affected area:

• Yellowish, flat, and thickened hard layer of dead skin
• Dry, waxy, or flaky skin
• Bleeding
• Pressure and pain
• Difficulty walking or grasping an object

A callus can form anywhere on your body where repeated friction, rubbing, and/or pressure occurs. It is most likely to appear in the following areas:

• Balls of your feet
• Heels of your feet
• Big toes
• Sides of your feet
• Knees
• Palms of your hands
  

How Do You Treat a Callus?

The type of treatment required for a callus depends on its location, its condition, and the symptoms it is causing. Your healthcare provider can identify a callus with a visual inspection.

Treating a callus involves relieving pain and alleviating the issue that caused the callus. Most calluses respond to conservative treatment.

Conservative Treatment

The following conservative strategies can treat a callus at home:

• Soak the callus in warm water. Soak the callus for about five to 10 minutes or until the skin softens.
• File the callus with a pumice stone. Dip a pumice stone in warm water, then use the stone to file the callus surface using a gentle circular motion to remove dead skin. Avoid exerting too much pressure, which could cause bleeding and infection.
• Apply moisturizing cream to the callus daily. Use a lotion or cream with salicylic acid, ammonium lactate, or urea. These ingredients will help gradually soften hard corns and calluses.
• Use padding. Protect your callus from further irritation during activity. Cut a piece of moleskin into two half-moon shapes and place it around the callus. A gel pad insert can also help relieve friction and pressure.
• Change your shoes. Tight or ill-fitting shoes can cause and irritate a callus.

Cutting and Trimming

A podiatrist can perform the following procedures to treat a callus:

• Callus reduction. This treatment involves shaving away the thickened, dead skin by carefully using a surgical blade to shave away the thickened, dead skin. The procedure is painless because the skin is already dead.
• Cortisone injection. A cortisone injection into a callus can reduce the pain caused by a larger callus.
  

Surgery

Surgery is rarely needed to treat a callus. It is usually reserved for calluses that don't improve with conservative treatment. Surgery is for when an abnormal bone structure, like a bunion or hammer toe, must be modified or removed to prevent a recurring callus. In this case, the surgery treats the underlying condition causing the pain.

How Do You Prevent a Callus From Forming?

Preventing a callus involves removing or cushioning your foot from the cause of friction or pressure. If you want to continue participating in an activity that increases your risk of developing a callus:

• Measure both feet to ensure that you're wearing the correct shoe size. If you have two feet of different sizes, wear shoes to fit the larger size.
• Measure your feet at the end of the day when they are the largest. Your feet naturally swell and settle throughout the day, so your size may change slightly.
• Wear properly fitting shoes appropriate for the activity.
• Look for shoes in which the ball of your foot fits comfortably in the widest part of the shoe.
• Choose shoes with a wide toe box that is deep enough to fit your toes without them rubbing on the top of your toes.
• Wear moisture-wicking athletic socks to prevent friction and sliding when running.
• Use gel pad inserts to decrease pressure and friction at points where your podiatrist indicates you may be at risk of forming a callus.
• Wear gloves to protect your hands during activities like lifting weights or gardening
• Wear pads on your knees when the bones of your knees are exposed to pressure during activities like laying carpet.

Summary

A callus is a dense, flat area of skin that hardens to protect an area subject to constant pressure or friction.

A callus can appear on any part of your body. It most often forms on the sides and soles of your feet and the palms of your hands. A callus can occur due to certain activities, such as gardening, weightlifting, or tennis, in which your hands or feet repeat an action that causes friction against a spot on your skin.

Conservative treatment at home can often repair a callus. A podiatrist can shave down the callus if these options don't work. The need for surgery, which is only necessary to shave or remove a bone structure that causes a callus to form, is rare.