What causes ingrown toenails

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Last updated: April 4, 2026

Quick Answer: Ingrown toenails, also known as onychocryptosis, occur when the edge or corner of a toenail grows into the soft flesh surrounding it. This is most commonly caused by improper nail trimming, wearing shoes that are too tight, or trauma to the toe.

Key Facts

What is an Ingrown Toenail?

An ingrown toenail, medically termed onychocryptosis, is a common and often painful condition where the edge or corner of a toenail grows into the soft flesh of the toe. While most frequently affecting the big toe, it can occur on any toe. The condition can range from mild irritation to severe inflammation, redness, swelling, and infection.

Common Causes of Ingrown Toenails

Several factors contribute to the development of ingrown toenails. Understanding these causes can help in prevention and management.

1. Improper Nail Trimming

This is by far the most frequent culprit. Cutting your toenails too short, too rounded, or tearing them can encourage the skin to fold over the nail edge, leading to it growing into the flesh. The correct way to trim toenails is straight across, not too short, and avoiding rounding the corners. This allows the nail to grow outwards, away from the skin.

2. Footwear Choices

Shoes that are too tight, too narrow, or have a pointed toe box can exert excessive pressure on the toenails. This constant pressure can force the nail to curve and grow downwards into the surrounding skin. High heels can also contribute by pushing the toes forward into the shoe's front.

3. Trauma and Injury

A direct injury to the toe, such as stubbing your toe, dropping something heavy on it, or repetitive stress from activities like running or kicking, can damage the nail or the surrounding tissue. This trauma can cause the nail to grow abnormally, leading to an ingrown condition.

4. Nail Shape and Genetics

Some individuals are genetically predisposed to developing ingrown toenails. Certain nail shapes, such as naturally curved or involuted nails (nails that curve inwards significantly from the base to the tip), are more likely to press into the skin as they grow.

5. Fungal Infections

While not a primary cause, fungal infections of the toenail (onychomycosis) can sometimes exacerbate or contribute to ingrown toenails. Fungal infections can cause the nail to thicken, become brittle, or change shape, potentially increasing the risk of ingrowth.

6. Poor Foot Hygiene

While less common, inadequate foot hygiene, especially in humid conditions, can create an environment where bacteria can thrive, potentially leading to infection if the nail breaks the skin barrier.

Who is at Risk?

Anyone can develop an ingrown toenail, but certain groups are at higher risk:

When to Seek Medical Advice

Mild ingrown toenails can often be managed at home with warm soaks and proper nail care. However, you should consult a healthcare professional if you experience:

A doctor or podiatrist can diagnose the condition and recommend appropriate treatment, which may include lifting the nail, partial or complete nail removal, or antibiotics if infection is present.

Sources

  1. Ingrown nail - WikipediaCC-BY-SA-4.0
  2. Ingrown toenail - Symptoms and causes - Mayo Clinicfair-use

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