What Causes Ingrown Toenails? Common Reasons and How to Prevent Them
A sore corner on your big toe can turn a normal walk, workout, or pair of cute shoes into an uncomfortable experience. If the skin beside your toenail feels tender, swollen, or irritated, you may be wondering: what causes ingrown toenails, and did something in your nail-care routine trigger it?
An ingrown toenail develops when the edge or corner of the nail presses or grows into the surrounding skin. The big toe is affected most often. Improper trimming is a common trigger, but tight shoes, naturally curved nails, injuries, repeated pressure, and certain nail conditions can also play a role.
Below, we’ll break down the most common causes, explain how clippers and nail files should be used safely, cover early warning signs, and help you decide when home care is reasonable—and when your toe needs professional attention.
Quick Answer
What causes ingrown toenails? The most common causes are cutting toenails too short or rounding the corners, wearing tight shoes, injuring the toe, repeated pressure, and having naturally curved nails. Incorrect filing or digging into the nail sides can also irritate the area. Proper straight-across trimming and roomy footwear can reduce your risk.
What Is an Ingrown Toenail?
An ingrown toenail happens when part of the nail edge begins pressing into or growing into the soft skin beside it.
At first, you may simply notice tenderness when you touch the corner of the nail. As irritation increases, the skin may become red or swollen. In some cases, an infection develops and you may notice drainage or pus.
According to the Mayo Clinic’s overview of ingrown toenails, typical symptoms include pain, tenderness, inflamed skin, swelling, and sometimes infection. Mayo Clinic’s ingrown toenail guide
Ingrown toenails are common, but that does not mean every painful nail corner should be treated aggressively at home. Cutting, filing, or digging deeper into a sore corner can sometimes make the irritation worse.
What Causes Ingrown Toenails?
Several factors can contribute to an ingrown toenail. Sometimes one cause is obvious. Other times, a few small factors work together.
1. Cutting Toenails Too Short
One of the most common mistakes is trimming the toenail extremely close to the skin.
A very short nail may look neat immediately after a pedicure, but removing too much of the free edge gives the surrounding skin more opportunity to press against the nail as it grows forward.
The risk can become greater when the corners are cut even shorter than the center.
For routine toenail grooming, the American Academy of Dermatology recommends cutting toenails straight across to reduce the chance of an ingrown nail. American Academy of Dermatology’s nail-trimming guidance
The goal is neat—not ultra-short.
Leave enough nail that you can still see the corners instead of trimming them below the surrounding skin.
2. Rounding or Digging Into the Corners
Toenails are not fingernails.
A softly rounded manicure shape may work well on fingernails, but aggressively rounding the sides of a toenail can create a small pointed edge lower down the nail.
As that hidden edge grows forward, it may press into the skin.
Avoid trying to create a deeply curved shape with clippers, scissors, or a nail file. A mostly straight edge is usually easier for the nail to grow forward without becoming trapped against the side of the toe.
3. Wearing Shoes That Crowd Your Toes
Your trimming technique may be perfect and you can still develop irritation if your shoes repeatedly squeeze your toes.
Narrow toe boxes, shoes that are too short, high heels, tight athletic shoes, or footwear that lets your foot slide forward can push the skin against the nail edge.
MedlinePlus identifies poorly fitting shoes and pressure on the toes as common contributors to ingrown toenails. MedlinePlus guidance on ingrown toenails
Pay special attention to fit if you:
- Run or walk long distances
- Spend many hours standing
- Regularly wear pointed-toe shoes
- Play sports involving running or kicking
- Notice toe soreness after wearing a specific pair
Your shoes should feel secure without forcing your toes together.
4. Naturally Curved Toenails
Some people simply have more curved toenails than others.
If the sides of your nail naturally curve downward, the edge may press toward the skin more easily. This does not mean you are doing anything wrong.
Trying to “correct” the curve by cutting farther down the sides can backfire.
Instead, keep the nail at a sensible length, trim mostly straight across, smooth only genuinely rough edges, and watch for recurring tenderness.
Repeated ingrown nails caused by the natural shape of the nail may need professional assessment.
5. Toe or Toenail Injuries
Stubbing your toe, dropping something on it, having the nail stepped on, or repeatedly hitting the front of your shoe can change the way the nail grows.
The nail may temporarily become:
- Thick
- Ridged
- Curved
- Split
- Loose
- Uneven
An altered nail edge may then begin pressing against the surrounding skin.
The American Academy of Dermatology advises seeking medical attention for certain more serious nail injuries, including particularly painful injuries or significant dark discoloration beneath the nail.
Do not aggressively reshape an injured nail simply to make it look normal again.
6. Repeated Pressure From Sports or Daily Activity
Not every nail injury is a dramatic accident.
Small amounts of pressure repeated hundreds of times can also irritate the nail.
Running, soccer, hiking, dancing, long walks, and certain work shoes can repeatedly push the big toenail against footwear.
Over time, that pressure can irritate the surrounding skin or contribute to changes in the nail.
If the same toe becomes sore after a particular activity, check both your nail length and your shoe fit.
7. Picking, Tearing, or Peeling the Nail Corners
A tiny sharp corner can be tempting to pull off with your fingers.
Try not to.
Tearing the nail gives you much less control than clipping or filing it. The tear may travel farther down the side than expected and leave an uneven spike behind.
The same applies to repeatedly picking at a corner because it “feels like something is there.”
Do not dig into a painful nail fold looking for a hidden edge.
If a corner is already swollen or painful, more manipulation can injure the skin.
8. Nail Infections or Other Nail Changes
A toenail that becomes unusually thick, distorted, brittle, or curved may be harder to trim correctly.
Mayo Clinic lists nail infections and certain medical conditions among possible contributors to ingrown toenails.
If one toenail suddenly becomes thick, yellow, crumbly, lifted, painful, or noticeably different from the others, do not assume it only needs stronger clippers.
A dermatologist or other appropriate healthcare professional can help determine what is causing the change.
Can Using a Nail File Cause an Ingrown Toenail?
A nail file itself is not normally the problem. How you use it matters.
After clipping, filing can be useful for smoothing a tiny sharp point or jagged free edge.
Problems are more likely when you push the file deeply down the side of the nail and try to remove the corner.
Aggressive side filing may:
- Make the corner too short
- Produce a pointed nail edge
- Irritate the nearby skin
- Thin the nail unnecessarily
- Cause tenderness or heat
- Create tiny skin injuries
For routine care, keep the file mainly on the visible free edge.
The AAD recommends smoothing rough or uneven edges with a nail file or emery board and filing in one direction rather than repeatedly sawing back and forth.
Choosing a Nail File
For a normal natural toenail, a fine or moderately fine file is usually easier to control than a very aggressive abrasive surface.
Thicker nails may need a sturdier file, but stronger does not mean you should use more pressure.
Your file should help smooth the edge—not carve into the side of your toe.
If filing causes pain, warmth, burning, or tenderness, stop.
Ingrown Toenail Risk Factors at a Glance
| Factor | How It Can Contribute | Smarter Habit |
|---|---|---|
| Cutting nails too short | Skin may press against the growing edge | Leave a small visible edge |
| Rounding the corners | Can create a hidden pointed edge | Trim mostly straight across |
| Tight shoes | Push skin and nail together | Choose a roomy toe box |
| Aggressive filing | May shorten or sharpen the nail sides | File only rough free edges |
| Toe injury | Can alter nail growth or shape | Protect the nail while it heals |
| Sports/repeated pressure | Causes ongoing nail trauma | Check shoe fit and nail length |
| Naturally curved nails | Edges may press toward skin | Avoid digging into the corners |
| Picking nail corners | Can create uneven tears | Use clean tools instead |
How to Trim and File Toenails More Safely
Good technique does not guarantee you will never develop an ingrown toenail, but it can remove several preventable risk factors.
1. Soften Hard Nails First
Toenails can be easier to cut after a shower or bath.
If your nails are particularly hard, brief exposure to lukewarm water may make controlled trimming easier.
2. Use Clean, Sharp Toenail Clippers
A sharp tool gives you more control than a dull clipper that crushes or tears the nail.
Use a toenail clipper sized appropriately for the thickness of your nail.
Keep personal grooming tools clean and avoid casually sharing clippers or reusable files.
3. Make Small, Controlled Cuts
Do not try to force a wide or thick toenail through one huge cut.
Work across the nail gradually.
Small cuts make it easier to control the final shape and reduce the chance of accidentally removing too much.
4. Cut Mostly Straight Across
Keep the corners visible.
Avoid following the natural curve of the toe so aggressively that the corners disappear below the skin.
The NHS also advises cutting toenails straight across rather than down the edges and avoiding shoes that pinch the toes. NHS nail-care guidance
5. File Only What Needs Smoothing
Once the main trimming is complete, run a fingertip lightly across the free edge.
If you feel a rough spot, use gentle file strokes until it no longer catches.
You do not need to dramatically reshape the whole nail.
6. Clean and Dry Your Tools
Remove visible debris after use and clean reusable tools appropriately for their material.
Store them dry.
Good hygiene becomes especially important if the skin around a nail is irritated or if you suspect a fungal nail problem.
Expert Tip: If a nail corner is already sore, resist the urge to keep clipping and filing until it “looks right.” Repeatedly working on the same corner can create a shorter, sharper edge. Stop grooming the area, reduce shoe pressure, and watch how the toe responds.
Early Signs of an Ingrown Toenail
Catching irritation early can help you avoid turning a minor nail problem into a much more painful one.
Watch for:
- Tenderness along one side of the nail
- Pain when pressing the nail corner
- Mild swelling
- Red or inflamed-looking skin
- Discomfort inside closed shoes
- Skin beginning to overlap the nail edge
More concerning signs include worsening swelling, drainage, pus, spreading redness, increasing pain, or feeling unwell.
Mayo Clinic recommends medical care when discomfort is severe, pus is present, or inflamed skin appears to be spreading.
What Can You Do at Home for a Mild Ingrown Toenail?
A mild, early ingrown toenail without signs of serious infection may improve with conservative care.
Mayo Clinic describes measures such as soaking the foot in warm, soapy water, using petroleum jelly and a bandage on the tender area, and choosing open-toed or otherwise comfortable footwear while symptoms improve.
The most important rule is to avoid turning home care into DIY surgery.
Do not:
- Cut deeply into the painful corner
- Dig beneath the nail with a file
- Tear away the nail edge
- Puncture swollen skin
- Try to drain pus yourself
- Keep trimming the nail shorter every day
If conservative care is not helping or symptoms are worsening, professional evaluation is the safer next step.
DIY Nail Care vs. Professional Care
| Situation | DIY Grooming May Be Reasonable | Professional Care Is Safer |
|---|---|---|
| Slightly rough nail edge | Yes, gentle filing | Usually unnecessary |
| Healthy nail needs trimming | Yes | Optional salon service |
| Mild tenderness after trimming | Monitor and reduce pressure | If it persists or worsens |
| Recurrent ingrown toenail | Limited benefit | Yes |
| Significant swelling or pus | No | Yes |
| Severe pain | No | Yes |
| Thick, distorted nail | Sometimes | If unexplained or difficult to manage |
| Diabetes or poor foot circulation | Extra caution required | Medical guidance is preferable |
Cost may affect your decision, but safety should come first. Clippers and files are inexpensive tools for routine grooming. A salon pedicure costs more and can help with cosmetic maintenance, but a nail technician does not replace medical evaluation for infection, severe pain, or an abnormal nail condition.
Healthcare and podiatry costs vary by provider, location, treatment, and insurance coverage.
Common Mistakes to Avoid
- Cutting the toenail extremely short. Shorter is not automatically healthier.
- Rounding both corners deeply. This can encourage a sharp edge to grow against the skin.
- Filing down the sidewall aggressively. A file should smooth, not dig.
- Picking at a painful corner. Repeated touching can irritate already-sensitive skin.
- Wearing tight shoes while the toe hurts. Pressure can keep the area inflamed.
- Using dirty tools. Keep clippers and reusable files clean and dry.
- Trying to cosmetically hide a worsening problem. Polish does not treat pain, swelling, drainage, or infection.
- Assuming every thick or curved nail is normal. Sudden nail changes deserve attention.
When to See a Nail Technician or Dermatologist
A nail technician can help with routine cosmetic nail care when the toenail and surrounding skin are healthy.
For example, a trained technician may help shorten and smooth healthy nails or identify when a nail looks unusual enough that a service should be postponed.
However, a nail technician should not be your main treatment provider for a painful, infected, bleeding, or severely ingrown toenail.
See a dermatologist, podiatrist, primary-care provider, or another appropriate healthcare professional if:
- Pain is severe or increasing
- Redness or swelling is spreading
- Pus or drainage appears
- The skin repeatedly bleeds
- The nail keeps becoming ingrown
- The nail has changed shape significantly
- You cannot trim the nail safely
- Home care is not helping
- You have a serious nail injury
People with diabetes, nerve problems, or poor circulation need extra caution with foot problems. MedlinePlus advises people with diabetes, poor circulation, nerve problems, or an infection around the nail to contact a healthcare provider rather than attempting routine home treatment of an ingrown nail.
FAQs
What is the most common cause of an ingrown toenail?
Improper trimming and pressure from footwear are two of the most common causes. Cutting toenails very short or rounding the corners can encourage the growing nail edge to press into nearby skin.
Can tight shoes cause ingrown toenails?
Yes. Shoes that squeeze your toes can push the surrounding skin against the nail edge. Narrow shoes, short shoes, and certain sports footwear may contribute to repeated pressure.
Can a nail file make an ingrown toenail worse?
It can if you aggressively file down the sides or dig underneath a painful corner. Use a file gently on the free edge to smooth rough spots rather than trying to remove an ingrown section yourself.
Should toenails be cut straight or curved?
Toenails are generally best trimmed mostly straight across. Avoid deeply rounding or removing the corners below the surrounding skin.
Can an ingrown toenail heal on its own?
Some mild cases improve with conservative care and reduced pressure. However, worsening pain, swelling, pus, spreading inflammation, or recurrent ingrown nails should be evaluated professionally.
Why do I keep getting an ingrown toenail on the same toe?
Recurring cases may involve trimming habits, footwear, repeated trauma, or the natural shape of your toenail. If the same nail repeatedly becomes painful, professional evaluation can help determine the cause and treatment options.
Is it safe to cut out an ingrown toenail at home?
Trying to cut deeply into an ingrown corner yourself can injure the skin and make the problem worse. MedlinePlus specifically advises against attempting to cut out the ingrown portion yourself.
Conclusion
So, what causes ingrown toenails? In many cases, the answer is a combination of nail shape, trimming technique, footwear, and pressure on the toe. Cutting toenails too short, rounding the corners, wearing tight shoes, toe injuries, naturally curved nails, and aggressive grooming can all contribute.
The good news is that several risk factors are manageable. Trim your toenails mostly straight across, leave the corners visible, gently file only rough edges, keep your tools clean, and choose shoes that give your toes enough room.
Most importantly, know where DIY nail care ends. A nail file can smooth a healthy edge, but it cannot diagnose or treat an infection or severe ingrown toenail.
Pay attention to what your toe is telling you. Gentle care today can help prevent a small nail problem from becoming a painful one later.
