An itchy patch between the toes or a nail that has yellowed and thickened — these are two manifestations of a fungal infection. Both have characteristic details — color, edge, thickness, and how everything changes over time. Below — about the causative agents, transmission routes, signs on the feet and nails, risk factors, and how the diagnosis is confirmed.
What it is and how it is transmitted
Foot fungus is a common fungal infection of the skin of the feet. Onychomycosis, or nail fungus (tinea unguium), is an infection of the nail plate by fungi of various families: its integrity is disrupted, color and transparency change, adherence to the nail bed decreases, and thickness changes. This is infectious onychodystrophy — a nail change caused by infection. Both forms are related: untreated skin fungus can spread to the nails. Foot fungus rarely resolves on its own and tends to recur.
The infection is transmitted from a person with such an infection. You can become infected by walking barefoot where someone has had fungus, especially in locker rooms and showers, as well as by touching affected skin. The risk increases when the feet are wet or sweaty or the skin is damaged. Scratching affected skin spreads the infection to other parts of the body. Foot fungus is not a reason to leave work or school.
Signs on the feet and nails
One of the main signs on the skin is itchy white patches between the toes. There may be painful and scaly areas; the skin may look red, although on dark skin this is less noticeable. Sometimes the skin cracks or bleeds. Not only the spaces between the toes are affected: the fungus affects the soles and sides of the foot, and sometimes causes fluid-filled blisters.
On the nail, there are three basic signs — the plate is brittle, discolored, or thicker than usual. The infection usually starts at the edge and spreads to the entire nail, making it even thicker and white or yellow. The plate becomes fragile and crumbles. Sometimes the nail completely separates from the bed — then the skin around it swells and hurts. Toenails are affected more often, sometimes fingernails. Sometimes the infection involves one nail and later spreads to neighboring ones. Nail fungus is not life-threatening but takes a long time to resolve.
Risk factors
Nail fungus occurs when the feet are constantly warm and moist. In general, the infection is more common under several conditions.
- Wet or sweaty feet.
- Footwear in which the feet become hot and sweaty, including prolonged wearing of sneakers.
- Damaged skin of the feet.
- Walking barefoot in locker rooms and showers where there are infected people.
- Untreated skin fungus near the nails.
How it is confirmed
The doctor takes a small scraping of skin from the foot and sends it to a laboratory to confirm fungus. Testing the sample is needed to confirm fungus specifically, not to assess the appearance of the area by eye. For a nail, a sample of the plate is taken and tested to determine the type of infection. If needed, the doctor refers to a dermatologist for further testing.
When to see a doctor
A reason to see a family doctor is severe pain, spread of the infection to other parts of the body, for example the hands, or involvement of several nails. Separately — diabetes and weakened immunity, including after organ transplantation or during chemotherapy: under such conditions, foot problems can be more serious than usual and require a doctor's examination. A hot, painful, and red foot or lower leg may be a more serious infection; on brown or black skin, redness is harder to see. Another reason is an infection that does not resolve.
Foot or nail fungus by itself is not a reason to call emergency services; 103/112 — if along with the skin infection there is difficulty breathing, facial swelling, or confusion.
The material is for reference: it describes signs, transmission routes, and how the diagnosis is confirmed, but does not replace a doctor's consultation.
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This content is for reference and does not replace a doctor's consultation. Medical disclaimer