Reviewed by Evan Lewis, PhD. Last updated 11 August 2026.
A callus is thickened skin your foot built where something rubs or presses repeatedly. It is not a growth and not an infection. What helps is reducing it gently, softening it, and changing the pressure that caused it, because a callus that keeps returning is a shoe problem wearing a skin disguise.
That last part is the bit most people skip. You can file a callus off every Sunday for a year and it will be back every Sunday, because the file treats the result and the shoe causes it.
What is the difference between a corn and a callus?
Size and focus. The StatPearls chapter on corns puts it precisely: a corn is a well-delimited focal area of hyperkeratosis, while a callus is a more diffuse type of callosity. The NHS says the same thing in plainer words, that corns are small lumps of hard skin and calluses are larger patches of rough, thick skin.
Practically: a corn is a point, a callus is an area. A corn usually hurts because it has a hard core pressing inward. A callus more often aches or burns across a broader patch, and plenty of them do not hurt at all.
Why does your foot make them at all?
Because it is protecting itself, and this is the single most useful idea on the page. StatPearls states it directly: a corn should be regarded as a symptom rather than a disease.
Thickened skin is your foot's response to repeated mechanical trauma from friction or pressure. StatPearls names who gets them most: athletes, people exposed to unequal friction from footwear or gait problems, older people, people with diabetes, and amputees. The common thread is not hygiene. It is load landing in the same place too often.
What does the location tell you?
Quite a lot, and this is the part that turns a callus from a nuisance into information.
| Where it is | What that usually means |
|---|---|
| Ball of the foot, under the big toe joint | Weight rolling through that point, often with a tight forefoot or high heels |
| Ball of the foot, under the smaller toes | Forefoot taking load it was not meant to, common with worn-out insoles |
| Outer edge of the heel | Landing on the outside of the foot, and often with open-backed shoes |
| Side of the little toe | Shoe too narrow at the toe box |
| Between the toes, soft and white | A soft corn, from toes pressing on each other |
| Whole sole, diffuse and dry | Worth checking it is not the moccasin pattern of athlete's foot |
If yours sits on the little toe, why corns form on the pinky toe covers that specific mechanism.
What actually helps?
The NHS list is the practical version, and it is worth following in order rather than jumping to the file.
- Change the shoe first. NHS advises wide, well-fitting, supportive shoes with a low heel and a soft sole that do not rub.
- Add cushioning. Thick cushioned socks, and soft insoles or heel pads.
- Soften before you touch it. Soak in warm water to soften the hard skin.
- Reduce it gradually. A pumice stone or foot file, regularly and lightly, rather than a lot in one session.
- Moisturise to keep the skin soft, which slows the rate it rebuilds.
NHS also advises against walking long distances or standing for long periods while you are dealing with one, and against high heels or tight pointy shoes.
Does salicylic acid work on calluses?
There is real trial evidence, and it is better than most people expect. StatPearls cites a randomised controlled trial comparing standard paring of calluses with 40% salicylic acid plasters. The salicylic acid group resolved more corns by proportion, delayed the time to recurrence, reduced pain and reduced corn size over six months compared with standard paring.
Two caveats. Keratolytic strengths run from about 12.6% up to 40%, so the product matters. And salicylic acid does not distinguish between thickened skin and healthy skin, which is why it belongs on the callus and not on the skin around it.
What should you never do?
The NHS is blunt on this one: do not try to cut off corns or calluses yourself.
- No blades, craft knives or callus shavers. Cutting hard skin at home is how a callus becomes a wound, and the wound is on the part of you that spends all day in a shoe.
- No aggressive electric grinders. Taking too much in one go leaves raw, thin skin that hurts more than the callus did.
- Do not file it to nothing. The callus is padding. Remove all of it and you are walking on unprotected skin over the same pressure point.
- Do not ignore a callus that has gone dark. A black or brown patch inside thickened skin can be bleeding underneath, which needs looking at.
Who should not treat these at home at all?
The NHS is explicit here, and this is the most important paragraph on the page. If you have diabetes, problems with your circulation, a weakened immune system, or are an older person, do not try to treat corns and calluses yourself. See a GP or foot specialist.
StatPearls explains why in mechanical terms: in the presence of peripheral sensory neuropathy, attempting this yourself may lead to excessive trimming and ultimately abrasion of the skin, because you cannot feel how deep you have gone. Its advice is for people with diabetes to have a podiatrist debride the callus safely.
Is it actually a callus?
Three things get mistaken for one, and each needs something different.
- A plantar wart. Skin lines run straight across a callus and stop at the edge of a wart, and warts often show tiny dark dots. Plantar wart vs corn vs callus compares all three, and the pinch test takes about ten seconds.
- A seed corn. Small, multiple, often on non-weight-bearing skin. Seed corns behave differently from a pressure callus.
- Moccasin athlete's foot. Diffuse dry scaling across the sole that never responds to moisturiser, usually worse on one foot. What athlete's foot looks like covers it.
When should you see someone?
NHS guidance is to see a GP if you get additional symptoms, or if you do not get any improvement after three weeks of treating it yourself. Also go if you have diabetes, circulation problems or a weakened immune system, regardless of how it looks.
Add to that: pain that changes how you walk, any redness, heat, swelling or discharge, and a callus that keeps rebuilding within days no matter what you do, which usually means the answer is in your gait or your shoe rather than your skin.
Thickened skin that cracks is also an opening, which is where the daily routine sits alongside the file and the cream. Sole Shield is the daily iodine spray we make for feet and shoes, used on clean dry skin and inside the footwear you put back on tomorrow.
Common questions
What is the difference between a corn and a callus?
A corn is a small, well-defined focal area of thickened skin, often with a hard centre. A callus is a larger, more diffuse patch. StatPearls describes the corn as a well-delimited focal hyperkeratosis and the callus as a more diffuse callosity.
Are corns and calluses contagious?
No. They are a mechanical response to friction and pressure, not an infection. That is one of the clearest ways to separate a callus from a plantar wart, which is caused by a virus and can spread.
Are calluses on feet genetic?
Not directly, though foot shape and gait are inherited and both affect where pressure lands. StatPearls lists gait problems and unequal friction from footwear among the causes, so what runs in families is usually the foot mechanics rather than the callus itself.
Can you cut a callus off yourself?
No. NHS guidance is not to try to cut off corns or calluses yourself. Reducing them gradually with a pumice stone or foot file after soaking is the safe version, and anything more should be done by a foot care professional.
Does salicylic acid work on calluses?
Yes, with trial evidence behind it. StatPearls cites a randomised controlled trial in which 40% salicylic acid plasters resolved more corns, delayed recurrence, reduced pain and reduced size over six months compared with standard paring.
Why do my calluses keep coming back?
Because the pressure has not changed. Skin rebuilds where load repeatedly lands, so unless the shoe, insole or gait changes, filing only resets the clock. The location of the callus usually tells you where to look.
Is a callus on the foot dangerous?
Not usually. NHS notes corns and calluses are not often serious. The exception is anyone with diabetes, circulation problems or a weakened immune system, where thickened skin can hide damage underneath and should be assessed rather than self-treated.
Should you remove a callus completely?
No. A callus is padding over a pressure point, and taking all of it leaves thin skin carrying the same load. Reduce it enough that it is comfortable, then deal with the cause.
Do podiatrists treat corns and calluses?
Yes, and it is routine work for them. They can debride safely, assess the gait or footwear cause, and fit padding or orthotics. For anyone with diabetes or neuropathy, StatPearls advises exactly this rather than home treatment.
The bottom line
A callus is a symptom, not a disease. Soften it, reduce it gradually with a file, moisturise, and then fix the shoe or the insole that put it there. Never cut it with a blade. And if you have diabetes, poor circulation or a weakened immune system, do not treat it at home at all, because NHS guidance is explicit that these conditions make foot problems more serious.
