How Are Warts and Calluses Different?

Warts and calluses are both benign skin growths, but they differ in their appearance, location, and causes.

Wart

Verruca, more commonly known as a wart, is a benign skin growth that develops in different areas of the body and can take on many forms. They arise in response to a virus. Warts are contagious and very common. They can range from a mild annoyance to a chronic invasion. Warts can be spread through skin to skin contact or by touching infected surfaces.[1] They are most commonly seen in children, young adults and those who have an immune system that does not work normally.[2]

Callus

Unlike warts, calluses are not contagious and do not result from an infection. Rather, they appear in response to increased pressure or repeated friction to an area. They most commonly appear on the hands and the bottom of feet and are seen in all ages.[3]

Corn

Just like calluses, corns also form on the skin in response to increased pressure of a particular area. They commonly appear on the top of feet, near the joint of the toe.[4] This is because the boney area on the toes does not have much cushion, and when constantly rubbed against a tight fitting shoe, it can create a thickened skin barrier for protection.

How Can You Tell a Wart vs Callus vs Corn?

Warts and calluses are often confused with each other. However, there are several features that define them from one another. Although not all warts are equal, there are some defining characteristics that distinguish them from calluses and other skin lesions. Some warts have many blood vessels, which present as tiny black dots on the surface. These dots are often confused as the “seeds of the wart”, but rather, they are capillaries.[1]

Calluses are generally hardened areas of skin but, unlike warts, they do not have blood vessels that are visible. The other defining characteristic is our natural skin lines. Since calluses are areas of thickened skin, the presence of skin lines throughout the hardened area will give a clue to a callus versus a wart, which will not have the normal skin lines present in the area of the wart.

It is common for ‘corn’ and ‘callus’ to be used interchangeably, which is reasonable since they both refer to the thickening and hardening of the skin. However, though the cause is similar, there are differences. Unlike calluses, corns contain a central core. This core can be hard or soft. The hard corn is the most commonly seen on the top of the foot.[4] Soft corns develop in between toes as a result of absorbing excess sweat in that area and are generally more painful than hardcore corns.[4]

Table 1. Characteristics of Warts vs Callus vs Corns

Wart Callus Corn Skin lines are not visible Multiple dark dots within the lesion Clearly defined margins Can occur anywhere on the foot Skin lines go through the lesion No blood supply in lesion Diffuse margins Present in weight-bearing areas Can have defined or diffuse margins Present on tops of feet, usually near the joint of the toes or in-between Hard or soft core Can be painful

What Are the Typical Causes of Warts and Calluses?

Warts

Warts develop in response to an infection by the Human Papilloma Virus (HPV). This DNA virus invades the skin, causing epithelial cells to grow rapidly. There are over 120 strains of the HPV virus.[5] Different strains cause different types of warts in various locations.

Calluses

Unlike warts, calluses develop on the skin in response to increased pressure, repetitive friction, or other irritants.[3] When skin is exposed to continuous friction, the outermost layer of the skin, the stratum corneum, begins to thicken as a defensive mechanism. Some causes include factors such as foot deformities or poorly fitted shoes.

How Are Warts and Calluses Treated?

Warts

Many warts can spontaneously resolve within 2 years in young children but may take up to five years to resolve in adults.[1] It is not uncommon for the wart to come back and spread. Therefore, treatment is recommended, especially in adults.

There isn’t a specific antiviral therapy for warts, but there are many treatments available that work by destroying the infected skin. The most common treatments for wart removal are salicylic acid, cryotherapy, and surgical removal.

Callus

There are many treatments and management options for calluses, which can be managed at home as opposed to multiple trips to the doctor’s office. One of the common culprits of calluses are poorly fitted shoes.[3] Changing shoes could help to minimize callus formation. Other treatments aim at the removal of the thickened and hardened skin. A pumice stone can effectively smooth thickened areas after soaking in warm water.[6] Over the counter creams containing either urea or salicylic acid can be applied for the removal of calluses due to their exfoliating properties.[7,8] However, the first line of medical intervention is scalpel debridement.[9] This is a minor painless procedure that entails a licensed professional to remove thickened areas of skin with the edge of a scalpel or sharp blade.

Table 2. Common Wart and Callus Treatments

Lesion Agent Administration Advantage Disadvantage Wart Patient-applied Salicylic Acid Daily application by patient Available over the counter. Not painful. Requires up to many weeks to resolve. Patient’s consistent use is critical. Provider-applied Salicylic Acid Application by practitioner Stronger formulation than over the counter. Not painful. Frequent application by a provider. Cryotherapy Liquid nitrogen application by practitioner Easy and potentially fewer treatments Painful and scarring Cantharadin Application by practitioner Not painful Causes delayed blisters and may cause less itching Candida antigen injection Injection by practitioner May stimulate the immune system to clear many warts including those that were not injected Painful. Requires multiple treatments. May not work in those with a weakened immune system Surgical removal Surgical removal of the wart by practitioner Removal of wart (only small ones) Painful and may scar, wart may recur Laser therapy Vascular laser by practitioner May destroy blood vessels within the wart Painful and requires anesthesia. Requires multiple treatments Callus Shoe Change Patient-driven shoe or insert modification Could alleviate callus formation Might not be the cause of the callus Pumice Stone Gentle removal of excess dead and thickened skin of the callus of area At home treatment. Good maintenance regimen. Not a permanent treatment. Must be done regularly. Patient-applied Salicylic Acid or Urea Cream Application to an area by patient Available over the counter. Good maintenance regimen. Not a permanent treatment. Must be done regularly. Scalpel Debridement Provider debris skin with a scalpel Quick and effective Not permanent

When to Seek Help?

If the lesion continues to enlarge in size

For practitioner guided treatment

Wart or callus does not improve despite over the counter treatments

Develop signs of infection to the area, such as tenderness, pus, and drainage.

In some cases, lesions that seem like a wart may be a sign of something more serious such as a skin cancer and it is very important that new lesions are evaluated by a dermatologist.