Corns and Calluses

Hard, thickened skin under the ball of the foot or the heel. A small dense spot on a toe that feels like standing on a pebble. Skin that you have been filing for months and that keeps coming back.

Callus is not a skin disease. It is armour. Skin thickens where it is loaded repeatedly, exactly as it does on a guitarist’s fingertips, and it is doing what it is supposed to do. It becomes a problem when the thickening itself starts generating pressure, at which point the protective response has turned into the source of the pain.

Corns and calluses are the same process at different scales

Callus is diffuse — a broad plaque of thickened skin over an area that takes more load than it was built for. It is usually painless at first and turns achy or burning as it deepens.

A corn is that same process concentrated into a small area. The thickening develops a dense central core that presses inward rather than outward, which is what produces the sharp, localised, standing-on-a-stone feeling. Corns turn up on the tops of toes, the tips of toes, between toes where two bones squeeze skin between them, and occasionally under the ball of the foot.

What is actually causing it

The hard skin is the visible end of a mechanical chain, and the chain is what an appointment is for:

• Footwear. Too short, too shallow in the toe box, too loose so the foot slides, or a seam sitting across a toe.
• Toe position. A hammer toe buckles a joint upward into the shoe, so a corn forms on top of it. A bunion pushes the first toe across and loads the joint beside it.
• How you distribute weight. A foot that pronates heavily, a stiff big toe, or a dropped metatarsal head all concentrate load onto one small area.
• Loss of the fat pad. The cushioning under the ball of the foot thins with age, which is why forefoot callus is far more common after sixty.
• Dry skin. Not a cause on its own, but dry callus splits, and a split in a weight-bearing surface is a route in for infection.

What happens at the appointment

Your podiatrist reduces the callus or enucleates the corn with a sterile scalpel. It is not painful — the tissue being removed has no nerve supply — and the pressure relief is usually immediate and obvious.

That is the quick part. The rest of the appointment is the part that decides whether you are back in eight weeks:

• Where the load is going, assessed standing and walking
• Your footwear, which is why bringing the shoes you actually wear matters
• Toe position and joint range
• Skin condition, circulation and sensation, particularly if you have diabetes

From there the options are padding or silicone devices to redistribute pressure, footwear changes, orthotics where the loading pattern is the driver, and a maintenance interval that suits how fast your skin rebuilds.

When hard skin is not a routine problem

⚠ If you have diabetes, peripheral neuropathy or poor circulation, callus is not cosmetic. Thickened skin over a pressure point is the single most reliable warning sign that precedes a foot ulcer, because the tissue underneath is being damaged before the surface breaks. It is also the point where self-treatment does the most harm.

Book a diabetic foot assessment rather than filing it, and never use acid corn plasters.

Anything that bleeds, discharges, smells, or is surrounded by red or warm skin needs looking at promptly rather than at the next convenient appointment.

A note on what a corn is not

Two things get mistaken for corns often enough to be worth naming.

A plantar wart is viral, not mechanical. It is painful pinched side to side rather than pressed straight down, often shows tiny dark points, and interrupts the skin lines rather than following them.

A foreign body — a splinter, a grass seed, a fragment of glass — produces a tender lump with callus built over it. Both are treated completely differently from a corn, which is the practical reason for having someone look at it rather than working on it yourself.