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Plantar Warts: What Are They?

That strange-looking bump on the bottom of your foot could be what’s known as a plantar wart. Plantar warts, caused by a virus, strike the soles of the feet, may occur alone or in bunches, and can be quite painful. If you think you have a plantar wart, make an appointment to see a podiatrist to receive a proper diagnosis and treatment.

Plantar Warts: What Are They?

A plantar wart is a wart caused by a type of human papillomavirus, or HPV, which enters the body through tiny cracks in the skin on the bottom of the feet.

Plantar warts:

  • Are found on the sole of the foot
  • May contain tiny black dots
  • Are flat and firm to the touch
  • Are gray, brown, or yellowish in color (and may even look like a callus, a rough patch of dead skin)
  • May be extremely painful, especially when walking or applying pressure

A plantar wart “can take any shape but often resembles a cauliflower with black speckles throughout the lesion,” says Timothy C. Ford, DPM, director of the podiatric residency program at Jewish Hospital & St. Mary’s HealthCare in Louisville, Ky.

Just one plantar wart may appear on your foot, but they can also pop up in bunches, known as mosaic warts. Most often, they are found on the ball or heel of the foot, but can occur anywhere on the sole of the foot.

Plantar Warts: Risk Factors

While anyone can get a plantar wart, young children and teenagers are particularly prone to them.

Plantar warts are “more common in children than adults as we build immunity with age,” explains Dr. Ford. Public showers and baths, pools, and locker rooms are all common areas where you can come into contact with the virus that causes plantar warts, says Ford.

Other risk factors for plantar warts include:

  • Touching another person’s wart
  • Walking barefoot in dirty areas
  • Walking barefoot in warm and damp areas

Plantar Warts: Diagnosis

Even if you’re pretty sure that you have a plantar wart, it’s best to go to a podiatrist for a diagnosis. In some cases, what you think might be a plantar wart is actually something more serious, like skin cancer. While this isn’t very common, it’s still better to check with a podiatrist to be sure.

If it is a plantar wart, you’ll need a podiatrist to treat the condition anyway — you shouldn’t try to take care of a plantar wart yourself. They are difficult to treat and may frequently come back. Often, plantar warts require surgical removal by a podiatrist.

“There are many ways to treat [plantar warts], from topical [medications] to surgical [procedures], depending on the symptoms and the length of time the wart has been present,” says Ford.

If you suspect you have a plantar wart, make an appointment to see a podiatrist so that you can get a proper diagnosis and treatment. Also, remember to be careful not to allow anyone else to come into contact with your plantar wart, as they can be contagious.

Common Foot Problems

Ingrown nails

What are ingrown nails?

Ingrown nails, the most common toenail problem, occur when the nail borders curve into the soft tissue of nail grooves. Ingrown nails cause pressure and pain along the nail borders. The edge of the nail may cut into the skin, causing redness, swelling, pain, drainage, and infection.

What causes ingrown nails?

Ingrown toenails are most commonly caused by shoe pressure. Ingrown toenails are also caused by:

  • Improperly trimmed nails
  • Crowding of toes
  • Repeated trauma to the feet from normal activities (such as running, walking or doing aerobics)
  • An inherited trait

How can I prevent ingrown nails?

  • Cut your toenails after bathing, when they are soft
  • Trim toenails with a nail clipper straight across, slightly longer than the end of the toes
  • Do not round off the corners of toenails or cut down on the sides of the nails
  • After clipping, smooth toenails with a file or emery board
  • Avoid wearing tight, restrictive shoes

How can ingrown nails be treated?

Following the preventative steps above can help you avoid the need for treatment. To relieve discomfort from ingrown toenails, soak your foot in a solution of lukewarm water and salt or lukewarm soapy water. Then apply an antiseptic and bandage the area.

If self-care measures are unsuccessful or if you have a nail infection, you may need a doctor’s care. Ingrown nails may be corrected with surgery by removing part of the toenail and growth plate. Continuing to care for your nails properly and wearing well-fitting footwear can help you prevent ingrown nails from recurring.

Mycotic nails

What are mycotic nails?

Mycotic nails are nails that become infected with a fungus. The nail may be discolored (yellowish-brown or opaque), thick, brittle, and separated from the nail bed. In some cases, the nail may crumble.

What causes mycotic nails?

  • Fungal organisms
  • Dark, moist, warm environment of shoes, which promotes fungal growth
  • Prior injury to nail, which can predispose nail to fungal infection

How can mycotic nails be prevented?

  • Examine the tops and bottoms of your feet each day. If you notice blisters, cuts, scratches or other sores, care for them immediately.
  • If you suspect an infected toenail, soak your foot in a solution of lukewarm water and salt, or lukewarm soapy water. Then apply an antiseptic and bandage the area. Although this may relieve discomfort, it is still recommended that you call a doctor.
  • Wash your feet every day with mild soap and lukewarm water. Gently and thoroughly dry your feet.
  • Care for your toenails regularly.
  • Don’t wait to treat a minor foot problem.

How can mycotic nails be treated?

If you notice an infected nail, do not try to remove any part of it. Also, avoid over-the-counter medications unless prescribed by your healthcare provider.

Fungal nail infections are difficult to treat. Topical medications are available, but they only help a small number of fungal nail problems. Oral medications may be prescribed instead, including:

  • Griseofulvin (Fulvicin®)
  • Terbinafine (Lamisil®)
  • Itraconazole (Sporanox®)

Other treatment methods include periodic removal of the damaged nail tissue and preventative management techniques.

Corns

What are corns?

Corns are a build-up of callus tissue (hard skin) near a bony prominence of a toe or between toes.

What causes corns?

Corns may be the result of pressure from shoes, which rubs against the toes or causes friction between the toes.

How can corns be prevented?

  • Wear properly fitted shoes; avoid very high-heeled, narrow shoes that push the toes forward, causing them to rub against the shoe.
  • Wear shoes with increased height or width in the toe area.
  • Use cushioned pads and insoles.

How can corns be treated?

If you have a corn, do not try to cut it or remove it with a sharp object. Instead, soak your feet first in lukewarm, soapy water and then use a pumice stone to gently remove the build-up of tissue. Do not use over-the-counter remedies to dissolve corns.

Corns may be treated by wearing shoes with increased height or width in the toe area and using cushioned pads and insoles. Medications may also be prescribed to treat corns.

When other treatments have not been successful, surgery may be recommended. Corrective surgery involves removing internal pressure by removing a piece of the bone or changing the position of the bone so corns do not form.

Calluses

What are calluses?

Calluses are a build-up of hard skin, generally beneath weight bearing bony surfaces. Calluses generally occur on the surface under the foot.

Some degree of callus formation on the sole of the foot is normal.

What causes calluses?

Calluses are caused by an uneven distribution of weight, generally on the bottom of the forefoot or heel. Calluses can also be caused by improperly fitting shoes or skin abnormality.

How can calluses be prevented?

  • Wear properly fitting, supportive shoes with shock-absorbing soles; avoid leather-soled shoes.
  • Use cushioned pads and insoles.
  • Limit periods of barefoot walking.

How can calluses be treated?

If you have a callus, do not try to cut it or remove it with a sharp object. Instead, soak your feet first in lukewarm, soapy water and then use a pumice stone to gently remove the build-up of tissue. Use cushioned pads and insoles. Medications may also be prescribed to soften calluses.

When other treatments have not been successful, surgery may be recommended. Corrective surgery involves removing internal pressure by removing a piece of the bone or changing the position of the bone so calluses do not form.

Blisters

What is a blister?

A blister is a shell on the skin surface that often contains a clear liquid. Blisters can become infected.

What causes blisters?

Blisters can form when the skin is repeatedly rubbed. For instance, this can happen when your shoes keep rubbing the same spot on your foot, when you wear shoes that don’t fit properly, or when you wear shoes without socks.

How can blisters be prevented?

  • Wear shoes that fit properly and comfortably.
  • Wear socks with shoes.
  • Use foot powder to help keep your feet dry.
  • Wear gloves when you are doing manual labor or working with your hands.

How can blisters be treated?

Do not break or “pop” the blister—the skin covering the blister helps protect it from infection. Gently wash the area with mild soap and water or a cleansing towelette, and then apply an antibacterial cream to the blister. Cover it with gauze, and secure it with hypoallergenic tape to help protect the skin and prevent infection. Change the dressing at least once a day, and wear different shoes until the blister heals.

Plantar warts

What are plantar warts?

Plantar warts look like calluses on the ball of the foot or heel. They may appear to have small pinholes or tiny black spots in the center. They are usually painful and may develop as a single wart or in clusters.

What causes plantar warts?

Plantar warts are caused by a viral skin infection that occurs on the outer layer of skin on the soles of the feet.

How can plantar warts be prevented?

  • Because it is unknown how the wart virus is transmitted, it is best to avoid direct contact with warts from another person or from one part of your body to another.
  • Limit periods of barefoot walking.

How can plantar warts be treated?

Do not use over-the-counter medications to dissolve the wart. If you are not sure if you have a plantar wart or a callus, let your doctor decide.

Plantar warts are difficult to treat with a 100 percent cure rate, since warts generally have an average lifespan of about 18 months, depending on the infecting virus. There is no vaccine to prevent plantar warts.

In a doctor’s office, topical medications and pads are often used to soften the thickened skin and relieve some discomfort. Freezing the plantar wart with liquid nitrogen is another form of treatment. Surgery may also be considered when other treatment methods are not successful.

When to see your doctor

If you have persistent foot pain, redness or swelling, it is important to visit your doctor. Self-diagnosis and treatment with over-the-counter remedies or “bathroom surgery” may delay treatment and cause more problems. Some foot problems are inherited or could be the sign of another health condition.

Diabetic Feet & Skin Care Information

Symptoms and Causes

Anyone can get the foot problems listed below. For people with diabetes, however, these common foot problems can possibly lead to infection and serious complications that could make amputation necessary.

Athlete’s foot — Athlete’s foot is a fungus that causes itching, redness, and cracking. Germs can enter through the cracks in your skin and cause an infection. Medicines that kill the fungus are used to treat athlete’s foot. These medicines may be pills and/or creams applied directly to the problem area. Ask your healthcare provider to recommend a medication for athlete’s foot.

Fungal infection of nails — Nails that are infected with a fungus may become discolored (yellowish-brown or opaque), thick and brittle, and may separate from the bed of the nail. In some cases, the nail may crumble. The dark, moist and warm environment of shoes can promote fungal growth. In addition, an injury to the nail can put you at risk for a fungal infection. Fungal nail infections are difficult to treat. Topical medications are available, but they only help a small number of fungal nail problems. Oral medications may be prescribed by your health care provider. Treatment also may include periodic removal of the damaged nail tissue.

Calluses A callus is a build-up of hard skin, usually on the underside of the foot. Calluses are caused by an uneven distribution of weight, generally on the bottom of the forefoot or heel. Calluses also can be caused by improperly fitting shoes or by a skin abnormality. Keep in mind that some degree of callus formation on the sole of the foot is normal. Proper care is necessary if you have a callus. After your bath or shower, use a pumice stone to gently remove the build-up of tissue. Use cushioned pads and insoles. Medications also may be prescribed to soften calluses. DO NOT try to cut the callus or remove it with a sharp object.

Corns — A corn is a build-up of hard skin near a bony area of a toe or between toes. Corns may be the result of pressure from shoes that rub against the toes or cause friction between the toes. Proper care is necessary if you have a corn. After your bath or shower, use a pumice stone to gently remove the build-up of tissue. Do not use over-the-counter remedies to dissolve corns. DO NOT try to cut the corn or remove it with a sharp object.

Blisters — Blisters can form when your shoes keep rubbing the same spot on your foot. Wearing shoes that do not fit properly or wearing shoes without socks can cause blisters, which can become infected. When treating blisters, it’s important not to “pop” them. The skin covering the blister helps protect it from infection. You also may use an antibacterial cream and clean, soft bandages to help protect the skin and prevent infection.

Bunion — A bunion forms when your big toe angles in toward the second toe. Often, the spot where your big toe joins the rest of the foot becomes red and callused. This area also may begin to stick out and become hard. Bunions can form on one or both feet. Bunions may run in the family, but most often they are caused by wearing high-heeled shoes with narrow toes. These shoes put pressure on the big toe, pushing it toward the second toe. The use of felt or foam padding on the foot may help protect the bunion from irritation. A device also may be used to separate the big and second toes. If the bunion causes severe pain and/or deformity, surgery to realign the toes may be necessary.

Dry skin — Dry skin can result if the nerves in your legs and feet do not get the message from your brain (because of diabetic neuropathy) to sweat, which keeps your skin soft and moist. Dry skin can crack, which can allow germs to enter. Use moisturizing soaps and lotions to help keep your skin moist and soft.

Foot ulcers — A foot ulcer is a break in the skin or a deep sore, which can become infected. Foot ulcers can result from minor scrapes, cuts that heal slowly or from the rubbing of shoes that do not fit well. Early intervention is important in treating foot ulcers. Ask your health care provider for advice on how to best care for your wound.

Hammertoes — A hammertoe is a toe that is bent because of a weakened muscle. The weakened muscle makes the tendons (tissues that connect muscles to bone) shorter, causing the toes to curl under the feet. Hammertoes can run in families. They also may be caused by wearing shoes that do not fit properly (are too short). Hammertoes can cause problems with walking and can lead to other foot problems, such as blisters, calluses, and sores. Splinting and corrective footwear can help in treating hammertoes. In severe cases, surgery to straighten the toe may be necessary.

Ingrown toenails — Ingrown toenails occur when the edges of the nail grow into the skin. Ingrown nails cause pressure and pain along the nail edges. The edge of the nail may cut into the skin, causing redness, swelling, pain, drainage, and infection. The most common cause of ingrown toenails is pressure from shoes. Other causes of ingrown toenails include improperly trimmed nails, crowding of the toes, and repeated trauma to the feet from activities such as running, walking, or doing aerobics. Keeping your toenails properly trimmed is the best way to prevent ingrown toenails. If you have a persistent problem or if you have a nail infection, you may need a health care provider’s care. Severe problems with ingrown nails may be corrected with surgery to remove part of the toenail and growth plate.

Plantar warts Plantar warts look like calluses on the ball of the foot or on the heel. They may appear to have small pinholes or tiny black spots in the center. They are usually painful and may develop singly or in clusters. Plantar warts are caused by a virus that infects the outer layer of skin on the soles of the feet. DO NOT use over-the-counter medications to dissolve the wart. If you are not sure if you have a plantar wart or a callus, let your health care provider decide.

How can diabetes affect my skin?

If your blood glucose is high, your body loses fluid, causing your skin to become dry. This occurs because the body is turning the water into urine to remove excess glucose from the blood. Your skin also can get dry if the nerves, especially those in your legs and feet, do not get the message to sweat (because of diabetic neuropathy). Sweating helps keep your skin soft and moist.

Dry skin can become red and sore, and can crack and peel. Germs can enter through the cracks in your skin and cause an infection. In addition, dry skin usually is itchy, and scratching can lead to breaks in the skin and infection.

Skin problems are common in people with diabetes. Blood glucose provides an excellent breeding ground for bacteria and fungi, and can reduce the body’s ability to heal itself. These factors put people with diabetes at greater risk for skin problems. In fact, as many as a third of people with diabetes will have a skin disorder related to their disease at some time in their lives. Fortunately, most skin conditions can be prevented and successfully treated if caught early. But if not cared for properly, a minor skin condition can turn into a serious problem with potentially severe consequences.

What are some common skin problems in people with diabetes?

Some of the problems listed below—such as bacterial infections, fungal infections and itching—are skin conditions that can affect anyone. However, people with diabetes are more prone to getting these conditions, which can lead to serious complications. Some of the conditions listed—such as diabetic dermopathy, necrobiosis lipoidica diabeticorum and eruptive xanthomatosis—occur only in people with diabetes. (Remember, people with diabetes also can develop skin conditions that affect people who do not have diabetes. )

Some common skin conditions include:

Acanthosis nigricans — This is a condition that results in the darkening and thickening of the skin. Often, areas of tan or brown skin, sometimes slightly raised, appear on the sides of the neck, the armpits, and groin. Occasionally, these darkened areas may appear on the hands, elbows, and knees. Acanthosis nigricans usually strikes people who are very overweight. There is no cure for acanthosis nigricans, but losing weight may improve the condition. Acanthosis nigricans usually precedes diabetes.

Allergic reactions — Allergic reactions to foods, bug bites, and medicines can cause rashes, depressions, or bumps on the skin. If you think you may be having an allergic reaction to a medicine, contact your healthcare provider. Severe allergic reactions may require emergency treatment. It is especially important for people with diabetes to check for rashes or bumps in the areas where they inject their insulin.

Atherosclerosis — Atherosclerosis is the narrowing of blood vessels from a thickening of the vessel walls. While atherosclerosis most often is associated with blood vessels in or near the heart, it can affect blood vessels throughout the body, including those that supply the skin. When the blood vessels supplying the skin become narrow, changes occur due to a lack of oxygen. Loss of hair, thinning and shiny skin, thickened and discolored toenails, and cold skin are symptoms of atherosclerosis. Because blood carries the white blood cells that help fight infection, legs and feet affected by atherosclerosis heal slowly when they are injured.

Bacterial infections — There are different kinds of bacterial infections affecting the skin. These include styes, which are infections of the glands of the eyelids; boils, which are infections of the hair follicles; and carbuncles, which are deep infections of the skin and the underlying tissue. There also are bacterial infections that affect the nails. With a bacterial infection, the areas involved generally are hot, swollen, red, and painful. Most bacterial infections require treatment with antibiotics in the form of pills and/or creams.

Bullosis diabeticorum (diabetic blisters) — In rare cases, people with diabetes develop blisters that resemble burn blisters. These blisters—called bullosis diabeticorum—can occur on the fingers, hands, toes, feet, legs, or forearms. Diabetic blisters usually are painless and heal on their own. They often occur in people who have diabetic neuropathy. Bringing your blood glucose level under control is the treatment for this condition.

Diabetic dermopathy — Diabetes can affect the small blood vessels of the body that supply the skin with blood. Changes to the blood vessels because of diabetes can cause a skin condition called diabetic dermopathy. Dermopathy appears as scaly patches that are light brown or red, often on the front of the legs. The patches do not hurt, blister or itch, and treatment generally is not necessary. The patches are sometimes called skin spots.

Digital sclerosis — The word “digital” refers to your fingers and toes, and “sclerosis” means hardening. Digital sclerosis, therefore, is a condition in which the skin on your toes, fingers and hands become thick, waxy and tight. Stiffness of the finger joints also may occur. The treatment is to bring your blood glucose level under control. Lotions and moisturizers may help soften the skin.

Disseminated granuloma annulare — This condition causes sharply defined, ring- or arc-shaped areas on the skin. These rashes most often occur on the fingers and ears, but they can occur on the trunk. The rash can be red, red-brown or skin colored. Treatment usually is not required, but some cases may benefit from a topical steroid medication, such as hydrocortisone.

Eruptive xanthomatosis — Eruptive xanthomatosis can occur in some individuals when blood glucose levels are not well controlled and when triglycerides in the blood rise to extremely high levels. This condition appears as firm, yellow, pea-like bumps on the skin. The bumps—which are surrounded by red halos and are itchy—usually are found on the feet, arms, legs, buttocks and backs of the hands. Treatment for eruptive xanthomatosis consists of controlling your blood glucose level. Lipid-lowering drugs also may be needed.

Fungal infections — A yeast-like fungus called Candida albicans is responsible for many of the fungal infections affecting people with diabetes. This fungus creates itchy red rashes, often surrounded by tiny blisters and scales. These infections most often occur in warm, moist folds of the skin. Three common fungal infections are jock itch, which appears as a red, itchy area on the genitals and the inside of the thighs; athlete’s foot, which affects the skin between the toes; and ringworm, which causes ring-shaped, scaly patches that can itch or blister. Ringworm can appear on the feet, groin, trunk, scalp, or nails. Medicines that kill the fungus may be needed to treat these infections.

Itching — Itching skin, also called pruritus, can have many causes, such as a yeast infection, dry skin or poor blood flow. When itching is caused by poor blood flow, the lower legs and feet are most often affected. Using lotion can help to keep your skin soft and moist, and prevent itching due to dry skin.

Necrobiosis lipoidica diabeticorum — Necrobiosis lipoidica diabeticorum (NLD) is caused by changes in the blood vessels and generally affects the lower legs. With NLD, the affected skin becomes raised, yellow and waxy in appearance, often with a purple border. Sometimes, NLD is itchy and painful. As long as the sores do not break open, treatment is not necessary. If the sores do break open, see your health care provider for treatment.

Scleroderma diabeticorum — Like digital sclerosis, this condition causes a thickening of the skin; but scleroderma diabeticorum affects the skin on the back of the neck and upper back. This condition, which is rare, most often affects people with diabetes who are overweight. The treatment is to bring your blood glucose level under control. Lotions and moisturizers may help soften the skin.

Vitiligo — Vitiligo is a condition that affects skin coloration. With vitiligo, the special cells that make pigment (the substance that controls skin color) are destroyed, resulting in patches of discolored skin. Vitiligo often affects the trunk, but may be found on the face around the mouth, nostrils and eyes. This condition usually occurs in people with type 1 diabetes. There is no specific treatment for vitiligo. You should use sunscreen with a SPF of 15 or higher to prevent sunburn on the discolored skin.

Assessing skin turgor (fullness) is a way for health care workers to assess the amount of fluid loss that may occur from various conditions, such as diarrhea or vomiting. Loss of body fluid through frequent urination also is a concern for people with diabetes. Skin turgor refers to the skin’s elasticity (its ability to change shape and return to normal). An assessment of skin turgor is used to help determine the effects of diabetes on skin health.

Spots on the Bottom of Your Feet

Taking good care of your feet includes checking them regularly for skin changes.

Image Credit: baona/iStock/GettyImages

Whether you’re just going about your day or trying to get in 10,000 steps, your feet work hard! Taking good care of them is one way to keep the momentum going. That includes checking your feet for any skin changes, like brown or dark spots. Pay special attention if you also have pain.

Whenever you have foot pain, start by checking your feet for any injuries, suggests board-certified dermatologist Deirdre Hooper, MD, an associate clinical professor at Louisiana State University and Tulane University in New Orleans. It could be something as simple as having a blister, which is a fluid-filled bubble that develops in an area of pressure and rubbing (friction) on your skin, explains Harvard Health Publishing. Most blisters clear up without requiring treatment, Harvard says.

“Most important is avoiding or fixing what caused friction,” says Rebecca Sundling, DPM, a podiatric surgeon at Foot and Ankle Specialists in Grand Rapids, Michigan. “Blisters filled with blood should be evaluated by a podiatrist.”

Read more:​ What Causes Blisters on the Bottom of Your Feet When Walking?

Splinters and stubbed toes can also leave you with a wound, notes Harvard Health Publishing. An ingrown toenail can cause redness, swelling and pain around the nail, says the American Academy of Family Physicians.

The Mayo Clinic suggests using over-the-counter ointment and changing dressings daily to treat small wounds. Remove small splinters by soaking your feet in warm, clean water or using sterilized tweezers, Dr. Hooper adds.

Minor foot injuries sometimes become infected because footwear creates the dark, damp environment where viruses, fungi and bacteria thrive, notes Penn Medicine at the University of Pennsylvania. Call your doctor if the wound doesn’t heal or develops signs of infection, like getting red, sore, swollen or discharging pus suggests the Mayo Clinic.

It’s also important to check the skin of your feet for changes in color or texture.

Some people develop rough, hard skin that’s white or yellow. This thickened skin, usually called a callus or corn, results from excess pressure or repeated rubbing in one spot, according to the U.S. National Library of Medicine. Treatment usually involves over-the-counter remedies, like pumice stones, notes the American Academy of Dermatology, or visiting a reliable nail salon.

The fungal infection athlete’s foot is another common cause of skin changes on your foot. This fungus lives in dark, damp places, like locker rooms and even shoes, describes the U.S. National Library of Medicine. When your feet come in contact with the fungus, it can transfer to the areas of skin between and underneath toes, says the Centers for Disease Control and Prevention (CDC).

If you have athlete’s foot, you may notice soft, moist, flakey spots between toes or scaly patches on your soles, reports the Cleveland Clinic. These patches may itch or burn. Over-the-counter products can be used to treat athlete’s foot, the clinic advises.

“Look for creams ending in -azole,” suggests Dr. Hooper. “Also, keep spaces between your toes dry. It may sound strange, but a hair dryer works best, especially if you’re prone to sweating.”

Round spots that are raised or grainy (and sometimes have a black dot in the center) may be warts, which are small skin growths caused by a virus, according to the U.S. National Library of Medicine. Warts on the bottom of your foot (plantar warts) are usually easy to treat with over-the-counter products or home remedies, according to the Cleveland Clinic. If warts are large, painful or spreading, call your doctor.

Psoriasis and contact dermatitis are other health conditions that can affect your feet, Dr. Sundling notes. Psoriasis causes skin cells to build up, forming itchy, dry patches, explains the National Psoriasis Foundation. According to the Mayo Clinic, contact dermatitis is an allergic reaction to something that touches your skin.

Read more:​ The 6 Best Anti-Inflammatory Foods for People With Psoriasis

The most serious type of discoloration may not be painful, and that’s why it’s important to check the skin of your entire foot — the top, bottom, between toes, and even the skin under your toenails. According to the American Podiatric Medical Association, this can help you spot skin cancer early, which is important for successful treatment.

According to a January 2018 study in the ​Journal of Foot & Ankle Surgery​, melanoma skin cancer ranks among the top 10 cancers for both women and men, and it may be more serious when it develops on the foot: In this study, just 50 percent of people with melanoma of the toe survived five years after diagnosis. (Earlier studies confirm higher survival rates for melanoma in other places on the leg.)

Dr. Sundling suggests using the “ABCDEs” of melanoma when checking spots on your feet, as recommended by the Centers for Disease Control and Prevention:

  • A​symmetry: Is the spot asymmetrical? (Does it have an
    odd, irregular shape?)
  • B​order: Does the
    spot have irregular or jagged borders?
  • C​olor: Is the
    spot uneven in color?
  • D​iameter: Is the
    diameter (distance between its edges) larger than a pencil eraser?
  • E​volving: Has
    the spot evolved (noticeably changed) over the past few weeks or months?

If you answer “yes” to any of these questions, contact a dermatologist to schedule an exam and have the spot removed for testing if necessary.

Lumps and Bumps on the Bottom of the Foot