What Is It?

Hyperkeratosis is a thickening of the outer layer of the skin, which contains a tough, protective protein called keratin. This thickening is often part of the skin’s normal protection against rubbing, pressure and other forms of local irritation, and causes calluses and corns on hands and feet, or whitish areas inside the mouth. Other forms of hyperkeratosis can occur as part of the skin’s defense against chronic (long-lasting) inflammation, infection, the radiation of sunlight, or irritating chemicals. Less often, hyperkeratosis develops on skin that has not been irritated. These types of hyperkeratosis may be part of an inherited condition, may begin soon after birth, and can affect skin on large areas of the body.

There are many examples of hyperkeratosis, including:

  • Corns and calluses — When areas of skin are exposed to repeated friction or pressure, thick layers of dead skin cells form the hardened areas we call corns and calluses. Corns usually develop on irritated toes, while calluses form on the soles of the feet and the palms of the hands. For many people, corns and calluses are simply a cosmetic nuisance, but for others, they are a painful and troublesome medical problem.

  • Warts — Warts are small bumps on the skin surface that are caused by a human papilloma virus (HPV) infection. Plantar warts grow on the soles of the feet. HPV usually is spread by direct contact, typically by touching or shaking hands with someone who already has a wart or by coming in contact with a contaminated surface, especially by walking barefoot on a gym floor or a pool deck, or by wearing someone else’s shoes.

  • Chronic eczema — Eczema, also called dermatitis, is an inflammation of the skin that can be triggered by allergies, irritating chemicals and other factors. Eczema produces itching, redness and tiny blisters. When the inflammation is difficult to control, chronic eczema can lead to hyperkeratosis, dry skin, scaling, changes in skin color and localized hair loss.

  • Lichen planus — This condition may appear as a lacy white patch on the inside of the mouth or as an itchy, violet, scaly patch elsewhere on the skin surface. Although the cause of lichen planus remains unknown, researchers suspect that it may be related to an abnormal reaction of the immune system.

  • Actinic keratosis — These are flat, red, rough patches of skin that are caused by excessive exposure to the ultraviolet radiation of sunlight. They can be as tiny as a few millimeters. They occur on sun-exposed areas of skin, and they have the potential to transform into squamous-cell carcinoma.

  • Seborrheic keratosis — These are small, noncancerous skin growths. They can be tan, brown or black, and are found on the face, trunk, arms or legs. Seborrheic hyperkeratoses are very common, and most people develop between one and 20 during their lifetime. Their cause remains a mystery.

  • Inherited conditions — Several inherited conditions cause hyperkeratosis. Lamellar ichthyosis, X-linked ichthyosis and ichthyosis vulgaris cause a widespread, thick, platelike scaling of the skin. Symptoms begin either shortly after birth or during early childhood.


Many forms of hyperkeratosis are painless. However, corns, calluses and plantar warts can cause a great deal of discomfort.


Depending on your specific pattern of skin symptoms, your doctor will ask whether you have a family history of skin problems, or whether you have a personal history of allergies, frequent sun exposure, wearing dentures or orthodontic dental appliances, unconsciously chewing on your cheek or tongue, or using smokeless tobacco.

Sometimes, your doctor can diagnose the cause of your hyperkeratosis by reviewing your history and symptoms and examining your skin. This often is the case with corns, calluses, warts and chronic eczema. If you have chronic eczema that could be allergy-related, the doctor may suggest that you have allergy testing.

If your doctor suspects that you have a seborrheic keratosis, he or she may use a hand-held magnifying lens to examine the affected skin for horn pearls. These are very tiny white or black balls of keratin that can usually be seen on the skin surface in areas of seborrheic keratosis. In some cases, a biopsy may be taken to confirm the diagnosis. In a biopsy, a small piece of tissue is removed to be examined in a laboratory. If your doctor suspects that you have actinic keratosis, you may need to have a skin biopsy to confirm the diagnosis and rule out skin cancer.

If your child develops hyperkeratosis in many areas of his or her body, your doctor may review family history and skin symptoms to determine if your child has an inherited disorder.

Expected Duration

How long a particular form of hyperkeratosis lasts depends on its cause. For example, corns and calluses usually will persist while a person continues to wear poorly fitting shoes. Warts may disappear on their own, although this may take several months.

Once an area of actinic keratoses or seborrheic keratosis develops, it is a long-term condition that does not disappear without treatment. Inherited forms of hyperkeratosis are lifelong conditions.


Some forms of hyperkeratosis are very easy to prevent:

  • Corns and calluses — Wear comfortable shoes.

  • Plantar warts — Decrease your risk by never going barefoot in gyms, locker rooms or pool areas.

  • Chronic eczema — Avoiding potential triggers, such as extreme temperatures, dry air, harsh soaps, bubble baths or irritating chemicals can help to limit or prevent eczema symptoms. You also can try using blankets and clothing made of cotton, rather than more irritating fabrics such as wool, silk and rough synthetics. Avoiding or removing triggers for your allergies also may help. When you have mild eczema, make sure you get and follow treatment advice to avoid developing chronic (long-lasting) eczema.

  • Actinic keratosis — Limit your sun exposure to early morning or late afternoon hours. Wear protective clothing and hats when you go outdoors, and always apply a sunscreen with a sun protection factor (SPF) greater than 15.


The treatment of hyperkeratosis depends on the type and possible cause:

  • Corns and calluses — Using moleskin or padding next to the affected area can help to relieve pain. Avoid further irritation that stimulates growth of the corn or callus. Never try to shave away or cut a corn or callus by yourself. Consult with your health-care provider or a podiatrist.

  • Warts — Your health-care provider or dermatologist can remove warts by freezing them with liquid nitrogen (cryosurgery), vaporizing them with a laser, or trimming them away surgically. If the treatment does not reach the layer of skin infected with the virus, the wart can come back in the same place. Repeat treatments may be necessary. Although warts can be treated at home with nonprescription remedies, self-treatment may take longer. Self-treatment may be more effective after you have been treated by a health-care provider, especially if the wart appears to be large or deep. If you have diabetes or poor circulation, you always should be treated by a health-care professional to avoid injury and infection.

  • Chronic eczema — Your doctor usually will treat eczema by prescribing a corticosteroid ointment or cream for you to rub into the affected area. Moisturizing the skin is also very important.

  • Lichen planus — Like chronic eczema, this usually is treated with corticosteroid ointment or creams.

  • Actinic keratosis — Your doctor may use cryosurgery to remove a single actinic keratosis. Multiple keratoses can be treated with skin peels, laser therapy or dermabrasion.

  • Seborrheic keratosis — This can be removed with cryosurgery with a scalpel.

  • Inherited conditions — There is no cure for these conditions. To treat large areas of scaly skin, your doctor may suggest bathing your child with bath oil or rubbing special emollients into the skin.

When To Call A Professional

Make an appointment to see your health-care provider or podiatrist if you have painful corns or calluses, or if you develop a painful thickening on your foot that looks like a plantar wart. People with diabetes should have their feet examined regularly by a podiatrist to avoid skin infections from corns, calluses or warts.

All adults should examine their skin regularly after age 20, especially if they have a history of working or playing for long hours in the sun. If you are not sure how to examine your skin yourself, ask your doctor for information about the proper technique. If you think you have an area of hyperkeratosis or eczema, you should schedule an appointment to see your health-care provider. Whenever you notice that a skin growth or mole has changed color, you should call your doctor for a more urgent appointment. Any new mole, brown or black growth on the skin, should be checked for signs of cancer. Also, if you have actinic keratosis and notice one has changed, you should also call your doctor for a more urgent evaluation.


Most forms of hyperkeratosis are local skin problems that have a good prognosis. Actinic keratosis can transform into squamous-cell skin cancer. Very rarely, seborrheic keratosis can develop into basal-cell skin cancers.

Johns Hopkins patient information

Last revised:

Diseases and Conditions Center

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All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.