Symptoms
Is it damage or fungus? Nail trauma vs infection
Runners, hikers and anyone who has dropped something on a toe often assume the worst. Trauma and infection look similar at a glance but behave very differently over time.
Summary
A traumatic mark stays the same size and moves up the nail as it grows. A fungal patch grows, changes colour and produces crumbly debris. Trauma also predisposes to infection, so both can be present in the same nail.
Distinguishing features
Watch it for six to eight weeks.
- Trauma: red, purple or black; a clear margin; grows out unchanged
- Fungus: white, yellow or brown; a spreading edge; thickening and debris
- Trauma often follows a memorable event or a new pair of shoes
- Fungus is often preceded by athlete's foot
Diagnosis
Nail clippings for microscopy and culture are the definitive test and are available through your GP. Dermoscopy by a podiatrist can also be informative.
When to seek medical advice
Urgently for a dark pigmented band that starts at the cuticle, widens, or extends onto the surrounding skin — this needs assessment to exclude melanoma.
References
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Medical disclaimer. This article is general information written for a UK audience. It is not medical advice and does not replace assessment by a GP, pharmacist or podiatrist. Always read the patient information leaflet supplied with any product before use.