What Causes Ingrown Toenails?
An ingrown toenail happens when the edge or corner of a toenail grows into the surrounding skin, often triggering pain, redness, swelling, and sometimes infection.
Understanding what causes ingrown toenails can help you spot avoidable habits, reduce recurrence, and know when medical care is needed.
The condition most often affects the big toe, but the underlying triggers are usually more predictable than people realize.
Small changes in nail trimming, footwear, or toe shape can create enough pressure to drive a nail edge into the skin.
How an Ingrown Toenail Forms
Toenails normally grow straight forward over the nail bed.
When the nail’s edge curves, breaks, or is cut too short, the skin at the side of the nail can be pushed upward and irritated by repeated pressure.
That irritation can lead to inflammation, which makes the skin swell around the nail.
Once swelling begins, the nail has less room to grow normally, creating a cycle that can worsen without treatment or a change in foot care habits.
Common Causes of Ingrown Toenails
Improper nail trimming
One of the most common answers to what causes ingrown toenails is cutting toenails too short or rounding the corners too aggressively.
When the nail edge is clipped deeply into the sides, it may grow back into the skin instead of extending straight ahead.
Using dull nail clippers, tearing nails by hand, or filing them unevenly can also leave jagged edges that irritate nearby skin.
Straight-across trimming is generally recommended because it helps the nail grow outward in a more stable shape.
Tight shoes and narrow toe boxes
Footwear that compresses the toes can push the nail and surrounding skin together with every step.
High heels, pointed shoes, and tight athletic footwear may increase pressure on the big toe, especially during long periods of walking or standing.
Repeated squeezing can cause the nail to curve, press into the skin, or create swelling that makes an existing edge more likely to become ingrown.
Shoes should allow enough room for the toes to spread naturally without friction or pinching.
Toe trauma and repetitive pressure
Stubbing a toe, dropping an object on the foot, or repeated impact from sports can damage the nail plate and the tissues around it.
Trauma may alter the way a nail grows, making it thicker, more curved, or more likely to dig into the skin.
Activities that place ongoing pressure on the toes, such as running, ballet, soccer, or hiking in ill-fitting shoes, can also contribute.
Even minor trauma repeated over time can matter, especially if the nail already has a curved shape.
Natural nail shape
Some people are more likely to develop ingrown toenails because of the way their toenails naturally grow.
A naturally curved or fan-shaped nail can increase the chance that an edge will turn downward into the skin as the nail lengthens.
Toe anatomy also plays a role.
People with toes that are unusually broad, tapered, or crowded may have less space for the nail to grow without touching the surrounding skin.
Risk Factors That Make Ingrown Toenails More Likely
Age and activity level
Ingrown toenails can happen at any age, but they are common in adolescents and young adults, partly because nails grow faster during growth periods and activity levels are often higher.
Sports, dance, and frequent running can all increase toe stress.
Excess sweating
Moisture softens the skin around the nail, making it easier for the nail edge to pierce or irritate the tissue.
People who sweat heavily in their shoes may notice more rubbing, friction, and skin breakdown around the toenails.
Foot conditions and biomechanics
Flat feet, bunions, hammertoes, or gait patterns that shift pressure toward the big toe can increase the likelihood of a nail becoming ingrown.
When the toe experiences uneven force, the nail edge may repeatedly press into the same area of skin.
Previous ingrown toenails
If you have had an ingrown toenail before, the same toe may be more vulnerable again.
Scarring, repeated inflammation, or a persistent nail shape issue can make recurrence more likely unless the underlying cause is addressed.
Diabetes and circulation problems
People with diabetes, peripheral artery disease, or reduced sensation in the feet may not notice early irritation.
Because small wounds can become serious more quickly in these groups, even mild nail problems deserve prompt attention.
What Makes an Ingrown Toenail Worse?
Several factors can turn a mild ingrown nail into a more painful or infected problem.
Continued pressure from shoes, picking at the nail, trying to cut the corner out yourself, and delaying treatment can all worsen inflammation.
If bacteria enter the irritated skin, the area may become infected.
Signs include increasing redness, warmth, throbbing pain, swelling, drainage, and foul-smelling discharge.
How to Prevent Ingrown Toenails
- Trim toenails straight across rather than rounding the corners.
- Keep nails at a moderate length; do not cut them too short.
- Use clean, sharp nail clippers to avoid jagged edges.
- Wear shoes with a wide toe box and enough depth for the toes.
- Change out of sweaty socks and keep feet dry when possible.
- Protect toes during sports or work that involves repetitive impact.
- Inspect feet regularly if you have diabetes or reduced circulation.
Prevention is usually easier than treatment because it focuses on removing pressure before the skin becomes inflamed.
A small adjustment in footwear or nail care can make a noticeable difference for people who get recurrent ingrown nails.
When to See a Healthcare Professional
Seek medical care if the pain is severe, the skin is draining pus, the toe is increasingly red or warm, or you have fever or spreading redness.
People with diabetes, immune suppression, or poor circulation should contact a clinician early, even for mild symptoms.
A podiatrist or primary care clinician can remove the problem portion of the nail, reduce pressure, and check for infection.
In recurrent cases, a minor procedure may be recommended to prevent the edge from growing back into the skin.
Questions People Often Ask About Ingrown Toenails
Are ingrown toenails caused by bad hygiene?
Not usually.
Poor hygiene can worsen an irritated toe or increase infection risk, but the main causes are usually nail trimming, shoe pressure, trauma, or nail shape.
Can ingrown toenails go away on their own?
Mild cases sometimes improve if pressure is reduced and the nail is allowed to grow out.
If pain, swelling, or infection is present, home care may not be enough.
Why do ingrown toenails keep coming back?
Recurring ingrown toenails often mean the original cause has not changed.
Common reasons include curved nails, narrow shoes, repetitive trauma, or trimming habits that continue to push the nail into the skin.
Which toe is most often affected?
The big toe is affected most often because it bears more pressure and is more likely to be squeezed by shoes or injured during activity.