Callus vs. Wart: What’s the Difference?

What can you do if you have a troublesome growth on your foot but aren’t sure what it is? If you’re trying to figure out whether it’s a callus or a wart, some distinctive differences can help you tell them apart. Calluses and warts have different causes, symptoms, and treatments.

What Is a Callus?

bottom of someone's feet with a callus
Image via Flickr by bark

A callus is a patch of hard, dry, thick skin. It may be gray or yellowish and bumpy. Calluses cover a large area of skin and have an irregular shape. Calluses are most prevalent on the bottom of your foot, where your bones support your weight. They can form on the ball of the foot, big toe, heel, or the area along the side of the foot. A certain amount of callusing on the bottom of your feet is normal.

Ill-fitting shoes can cause calluses. They can also form in areas of repetitive pressure from different sports. Calluses can also develop due to an abnormal gait. An abnormal gait can result from differences in one’s hip, legs, or feet. Calluses can also result from bone structure issues, such as bone spurs or flat feet.

Calluses can also be caused by not wearing any socks with your shoes. Ill-fitting, nylon, or other synthetic socks can cause your foot to move around more in your shoes, as well as lead to excess sweating. Wearing high heels also causes foot compression. Loose-fitting shoes can cause excess friction, too, so getting the fit of your shoes right is vital.

How Is a Callus Diagnosed?

A doctor’s examination may determine that another treatment is needed. First, they’ll rule out other conditions that can also cause skin thickenings, such as a cyst or wart. They may order an X-ray if they suspect that a physical abnormality is the cause of a callus.

How Is a Callus Treated?

If you have a callus that lingers over time or is painful even after you have taken self-care measures, it can be treated in the following ways:

  • Your doctor may opt to trim away the callus using a scalpel, paring down the thickened skin. This can be done on an outpatient basis. Don’t try trimming a callus yourself, as you may nick healthy skin below or around it, and that can cause an infection.
  • You may be given callus-removing medication, or your doctor may opt to apply a patch. These patches contain 40% salicylic acid and don’t require a prescription. Your doctor will provide instructions for how long to wear the patch and when it needs to be replaced with a fresh one. 
  • However, if you have a larger area affected by a callus, your doctor may elect to prescribe you salicylic acid in gel form.
  • Your doctor may also recommend using a pumice stone, emery board, or nail file at home to smooth away dead skin before you apply a new patch or reapply gel.
  • Your doctor may recommend shoe inserts. If your calluses have resulted from an underlying deformity in your feet, you may be prescribed custom-made orthotics to cushion your calluses; these orthotics can also help heal and prevent calluses from reoccurring.
  • In rare cases, you may require surgery if your calluses result from friction caused by a misaligned bone.

What Is a Wart?

A wart differs from a callus and has a different cause as well. A wart is caused by various strains of the human papillomavirus (HPV) and appears as a small, fleshy painless bump or growth on the skin or mucous membrane. Different strains of HPV can cause warts to appear on other areas of the body. They can also spread from one area of the body to another and can be passed to another person if they come into contact with the wart.

How Is a Wart Diagnosed?

Your doctor can determine if you have a wart in any of the following ways:

  • Your doctor examines the wart.
  • Your doctor scrapes off the top layer of the wart, checking for any signs of dark, pinpoint dots, which indicates the presence of clotted blood vessels, a common sign of warts.
  • Your doctor can perform a shave biopsy, which is done by removing a small section of the wart and sending it to a laboratory for testing to rule out other kinds of skin growths.

How Is a Wart Treated?

  • Your doctor may use peeling medicine containing prescription-strength salicylic acid, which works a bit at a time to remove the layers of a wart. This treatment is most effective if used in combination with cryotherapy (freezing therapy).
  • Cryotherapy is done at your doctor’s office. Liquid nitrogen is applied to the wart and forms a blister around and under the wart. This process causes the dead tissue to shed over a week or so. Cryotherapy may help stimulate your immune system to prevent warts from recurring. This treatment usually needs to be repeated for continued effectiveness. Cryotherapy does have side effects, including blistering, pain, and discoloration of the skin in the treatment area. Due to the discomfort of this treatment, it’s not usually used in the case of young children who have warts.
  • If cryotherapy, salicylic acid, or the combination of both treatments doesn’t work, your doctor may opt to use trichloroacetic acid on your wart. After shaving the surface of your wart, your doctor will apply the acid. The treatment needs to be repeated periodically, usually every week or so. This method’s side effects are stinging and burning sensations.
  • If none of the other treatments work, your doctor can perform minor surgery to remove the wart. It may leave a small scar.
  • Pulsed-dye laser treatment cauterizes (burns) small blood vessels. This causes the infected tissue to die, leading the wart to fall off. This method can cause pain and scarring, and there isn’t enough evidence proving its effectiveness.

While this information can give you a better idea of what’s going on with your feet, professional medical care is always recommended when you notice a problem. Whether you think you have a callus or a wart, resist the urge to diagnose or treat yourself, and seek help from your primary care doctor or a podiatrist. If you have a growth on your foot or are experiencing any other foot issues, reach out to Dr. Schoene at Gurnee Podiatry and Sports Medicine Association.