Corns and Calluses: Symptoms, Causes, and Prevention

It often happens that sometimes you feel the skin hardened under or on your feet or on your knuckles. They have a layer of hard dead skin covering them and you feel that if you remove the hard skin or massage it long enough, the skin there would be soft and supple again. These are nothing but corns and calluses that are caused by frequent friction or pressure on the skin. 

They may appear as a thickened layer of yellowish skin, a raised bump or dry, flaky, or waxy skin. They could cause discomfort, tenderness, or pain. However, you shouldn’t try to remove the dead skin off-hand as it may lead to infection. Corns and calluses are temporary and can be easily treated unless you have a medical history.   

Corns

Corns are hardened dead skin and are smaller than calluses. They usually appear on the skin of your fingers, toes, palms of your hands, and soles of your feet. A corn has a center, which is called the core. It appears as a dense knot located at the point of maximum friction. Corns can be very painful when pressed. Generally, corns occur in the non-weight-bearing regions of the foot.

In the feet, corns can be of three types: 

• Hard: Dry and firm corn, which usually appear on the upper surface of the toes.
• Soft: Pliable and moist corns, which occur between the toes.
• Seed: A plug-like circle of dead skin which appears on the heel or ball of the foot, and is very painful.

Calluses

Bigger than corns, calluses are a thick layer of dead skin found on the hands, fingers, toes, and soles. The thickening is even. However, calluses can vary in shape and size. They are flat, yellowish, and mostly, not painful.

Causes

• Wearing ill-fitting shoes which compress your feet and subject the skin to friction.
• Not wearing socks or wearing the wrong kind of socks can cause friction.
• Calluses on the fingers are formed when you perform any activity that requires a firm grasp such as holding a pencil or pen, playing a stringed instrument, playing racquet sports, using gardening or home tools, playing tennis, using gym equipment, driving, etc. Due to the firm grasp, there is repeated rubbing, which causes friction leading to calluses.
• On the feet, calluses are caused by friction from the shoes near the base of the toes, heels, and balls. Sometimes, they can also be caused by abnormalities that subject the foot to friction or abnormal gait (manner of walking).

Additionally, there are risk factors which contribute to the formation of corns and calluses like:

• Bunions: A bony bump at the base of the big toe
• Hammertoe: A deformity where the toe curls like a claw
• Bone spurs: Bone growths exposed to friction

Symptoms 

• Pain
• Dry, flaky and waxy skin
• Difficulty in walking
• Difficulty in grasping
• If the irritation persists, brown or red discoloration occurs under the callus or corn. This occurs because of bleeding in the space between the thick and normal skin making the skin susceptible to infections

Prevention

• Keep your toenails trimmed
• Wear hand gloves for protection while using tools
• Wear comfortable and cushioned socks
• Wear shoes that fit well so that friction between the toes and shoes is minimal
• Shop for shoes at the end of the day when the foot is swollen and the shoe fit is accurate
• Avoid shoes with sharp and pointed toes and heels
• Replace shoes regularly when worn out

Home remedies

• Cushion the affected area with a moleskin pad to relieve pressure
• Soak the affected area in warm water. Dry the area and gently rub a pumice stone on it. Then apply moisturizer
• Use over-the-counter ointments like salicylic acid to soften the corn or callus

When to see a doctor?

• If the area gets infected
• If there is pus discharge from the corn or callus 
• If you have diabetes or any other disease of the circulatory system that causes poor blood flow to the affected area

Diagnosis

• Simple inspection of the hands and feet is good enough to diagnose a corn or a callus.
• The doctor may examine your feet to check for warts or cysts, or recommend an x-ray to check for physical abnormality causing corn or callus.
• They may look for toe deformities, structural alignments of bones and gait.
• They may ask for any medical history such as diabetes and circulation problems, which may be helping in the progression of the disease.
• Any surgery on the foot may affect the structural alignment of the bones increasing the risk of calluses and corns.

When to visit a foot specialist

If the corn or callus is very painful and it interferes with your daily activities, you need to see a podiatrist (foot specialist).

• Trim away the excess skin: The doctor will remove the excess skin with a scalpel. Do not attempt this yourself. 
• Shoe insert recommendation: The podiatrist assesses the structural issues with the foot, checks for gait, recommends special padding or shoe inserts (orthotics) that redistribute the pressure on the feet.
• If the corn or callus is infected, the doctor may prescribe an antibiotic.
• In extreme cases, surgery is performed to remove the corn or correct the underlying bony issue.  

Most of the time, corn and calluses are not a medical complication, so you might ignore them. In some cases, they can be painful and infection may occur. If your problem persists, consult a doctor and share your family and medical history in order to plan treatment.

References
1. Calluses and corns. Harvard Health Publishing. 2015. https://www.health.harvard.edu/pain/calluses-and-corns (accessed Mar 23, 2021).
2. Finding relief from calluses and corns. Harvard Health Publishing. https://www.health.harvard.edu/pain/finding-relief-from-calluses-and-corns (accessed Mar 23, 2021).
3. Corns and calluses. MayoClinic. https://www.mayoclinic.org/diseases-conditions/corns-and-calluses/symptoms-causes/syc-20355946 (accessed Mar 23, 2021).
4. How To Treat Corns And Calluses. American Academy of Dermatology Association. https://www.aad.org/public/everyday-care/injured-skin/burns/treat-corns-calluses (accessed Mar 23, 2021).
5. Understanding Corns and Calluses — the Basics. WebMD. https://www.webmd.com/skin-problems-and-treatments/understanding-corns-calluses-basics (accessed Mar 23, 2021).