An ingrown fingernail (onychocryptosis) occurs when the edge of the nail plate grows into the soft flesh of the surrounding nail fold. This penetration creates a small wound, triggering an inflammatory response. The break in the skin barrier allows common bacteria, such as Staphylococcus aureus, to enter the tissue, often leading to a secondary bacterial infection known as paronychia. The presence of infection causes symptoms to progress from simple irritation to a painful condition requiring attention.
Visual Signs of an Infected Ingrown Fingernail
The most noticeable sign of an infected ingrown fingernail is localized bright redness (erythema) around the nail edge where the nail pierces the skin. This redness results from increased blood flow as the body attempts to fight the bacteria. As inflammation worsens, the skin begins to swell (edema), causing the tissue to appear puffy over the nail margin.
The infected area is typically warm to the touch, indicating localized inflammation and increased blood circulation. Pain associated with an infection is usually constant and throbbing, often feeling more intense than the initial discomfort. This pain is generally localized to the specific side of the nail where the ingrowth has occurred.
A definitive sign of bacterial infection is the presence of drainage or pus. This purulent drainage appears as a yellowish or whitish fluid that collects near the nail fold or leaks from the site of penetration. In advanced cases, persistent inflammation can lead to the formation of friable granulation tissue, which is a lumpy, reddish tissue that bleeds easily and may grow over the nail edge.
Common Causes of Ingrown Fingernails
The primary mechanical reason for an ingrown fingernail is improper trimming technique, specifically cutting the nails too short or rounding the edges. When the nail is cut with a curved shape, the remaining edge presses into the skin as the nail grows out. Nails should be trimmed straight across to prevent this inward growth.
Nail biting and picking at the skin around the nail are also common causes, as they damage the protective skin barrier and create an entry point for bacteria. Repetitive pressure on the fingertips, such as from forceful typing or tight-fitting gloves, can force the nail to grow abnormally. Direct injury, crush trauma, or a naturally excessive curvature of the nail plate can also increase the likelihood of the edges growing into the skin.
When to Seek Medical Attention
While mild ingrown fingernails can often be managed with home care, several warning signs indicate the need for professional medical evaluation. Immediate care is necessary if the infection shows signs of spreading or if the patient has underlying health risks.
Signs Requiring Medical Attention
- Severe pain that prevents normal daily activities or sleep.
- A fever or chills accompanying the local infection, suggesting systemic spread.
- Red streaking (lymphangitis) extending from the affected nail up the finger or hand, indicating the infection is traveling through the lymphatic system.
- No improvement after two to three days of careful home treatment.
Individuals with pre-existing health conditions, such as diabetes, poor circulation, or an impaired immune system, should seek care promptly. These patients face a higher risk of developing serious complications, including deep tissue infection or bone infection.