From the Guidelines
Calluses are primarily caused by repeated friction, pressure, or irritation, often resulting from wearing ill-fitting shoes, engaging in physical activities that involve repeated contact or pressure on specific areas, or having medical conditions such as bunions or hammertoes that create abnormal pressure points. The development of calluses can be attributed to various factors, including:
- Wearing ill-fitting shoes that rub against the skin, particularly on the feet, heels, and toes 1
- Regular use of tools or instruments without gloves, leading to callus formation on hands, especially on palms and fingers
- Physical activities like weightlifting, playing musical instruments, or manual labor that lead to callus formation in areas of repeated contact
- Medical conditions such as bunions, hammertoes, or other foot deformities that create abnormal pressure points, developing into calluses 1 Calluses are the body's protective response to prevent damage to underlying tissues, but excessive calluses can become painful and may require treatment. Prevention methods include wearing properly fitted shoes, using protective gloves during activities, and padding areas of friction 1. For severe or painful calluses, especially in people with diabetes or circulation problems, professional medical treatment is recommended rather than self-treatment 1.
From the FDA Drug Label
Urea is useful for the treatment of hyperkeratotic conditions such as dry, rough skin, dermatitis, psoriasis, xerosis, ichthyosis, eczema, keratosis pilaris, keratosis palmaris, keratoderma, corns and calluses, as well as damaged, ingrown and devitalized nails. The causes of calluses are not directly stated in the drug label. Key points:
- The drug label mentions calluses as a hyperkeratotic condition, but does not provide information on the causes. 2
From the Research
Causes of Calluses
- Abnormal foot pressures, particularly shear stresses, can lead to callus formation 3
- Peripheral neuropathy, a common complication of diabetes, can cause motor neuropathy leading to deformity and sensory neuropathy, resulting in persistent abnormal pressure on the foot, which can lead to callus development 4
- Gait factors, such as small flexion of the knee joint and large ankle pronation motion, can increase external forces on the foot, contributing to callus formation 5
- Wearing ill-fitting footwear, including shoes that are too long or too tight, can also contribute to callus formation 5, 6
- Hyperkeratosis, a thickening of the skin, can occur in response to abnormal pressure and friction, leading to callus formation 4, 7
Risk Factors
- Diabetes, particularly diabetic neuropathy, is a significant risk factor for callus formation 3, 5, 4, 7, 6
- Footwear and insole design features, such as rocker soles and custom-made insoles, can reduce plantar pressures and may help prevent callus formation 6
- Gait abnormalities and deformities, such as those caused by peripheral neuropathy, can increase the risk of callus formation 5, 4