Foot Infections
Bacterial and fungal infections of the skin, nails, and tissues of the foot
Quick Facts
- Type: Skin and soft-tissue infection
- Causes: Bacteria and fungi
- Common forms: Athlete's foot, nail infection, cellulitis
- Higher risk: People with diabetes
Overview
Foot infections occur when bacteria or fungi invade the skin, nails, or deeper tissues of the foot. They are very common, partly because the feet spend long hours in warm, moist, enclosed shoes, which is an ideal environment for germs to grow, and partly because the feet are easily injured. Foot infections range widely in severity, from mild and easily treated, such as athlete's foot, to serious deep infections that require urgent medical care.
Most healthy people recover quickly from minor foot infections. However, in people with diabetes, poor circulation, or a weakened immune system, even a small foot infection can become serious. Reduced sensation and slow healing allow infections to spread and reach deeper tissues, including bone, before they are noticed. For this reason, knowing the warning signs and getting prompt treatment is especially important for higher-risk groups.
Types and Symptoms
Foot infections take several forms with overlapping symptoms:
- Athlete's foot (fungal skin infection): Itching, burning, peeling, cracking, and redness, often between the toes.
- Fungal nail infection: Thick, discolored, brittle, or crumbling toenails.
- Bacterial skin infection (cellulitis): Spreading redness, warmth, swelling, and pain, sometimes with fever.
- Infected wound or ulcer: Pus, foul-smelling drainage, increasing pain, and surrounding redness.
- Deep infection or abscess: A painful, swollen, warm area, sometimes with fever and feeling generally unwell.
Warning signs of a serious infection include spreading redness, severe pain, fever, red streaks moving up the leg, or a wound that worsens quickly. These need prompt medical attention.
Causes
Foot infections develop when germs enter the skin or grow on it. Common causes include:
- Fungi: Thrive in warm, damp conditions and cause athlete's foot and nail infections, often spread in showers, locker rooms, and pools.
- Bacteria: Enter through breaks in the skin, such as cuts, blisters, cracks, insect bites, or ingrown toenails, and cause cellulitis and deeper infections.
Anything that breaks the skin barrier or keeps the feet moist increases the risk. Cracks from dry skin or athlete's foot can let bacteria in, which is why fungal and bacterial infections sometimes occur together. In people with diabetes or poor circulation, reduced sensation and slow healing make it easier for infections to take hold and spread.
Risk Factors
- Diabetes, especially with nerve damage or poor circulation
- A weakened immune system
- Cuts, blisters, ingrown toenails, or cracked skin that break the skin barrier
- Sweaty feet and wearing tight, non-breathable shoes
- Walking barefoot in shared wet areas such as locker rooms and pools
- Poor foot hygiene
- Existing athlete's foot, which can let bacteria in
Diagnosis
Many foot infections are diagnosed by examination, with tests used in more serious or uncertain cases:
- Physical examination: Assessing the location, appearance, drainage, and extent of the infection.
- Skin or nail samples: To confirm a fungal infection when the diagnosis is unclear.
- Wound cultures: To identify the bacteria causing an infected wound and guide antibiotic choice.
- Imaging: X-rays or scans if a deep infection or bone involvement (osteomyelitis) is suspected.
- Circulation tests: In people with diabetes or suspected poor blood flow.
Treatment
Treatment depends on the type and severity of the infection:
- Fungal infections: Antifungal creams, sprays, or powders for athlete's foot, and oral antifungal medicine or medicated nail treatments for stubborn nail infections.
- Bacterial skin infections: Antibiotics, taken by mouth for many cases and given in hospital for severe infections.
- Wound care: Cleaning, dressing, and sometimes removing dead tissue from infected wounds or ulcers.
- Drainage: An abscess may need to be drained.
- Treating the cause: Improving blood sugar control and circulation in people with diabetes, and addressing ingrown nails or other entry points.
Serious or deep infections, particularly in people with diabetes, may require urgent hospital care to prevent spread and protect the foot.
Prevention
- Keep your feet clean and dry, and dry carefully between the toes
- Wear breathable shoes and moisture-wicking socks, and change socks if your feet get sweaty
- Wear sandals in locker rooms, showers, and around pools
- Treat athlete's foot promptly to prevent cracks that let bacteria in
- Care for cuts, blisters, and ingrown nails quickly, and do not go barefoot
- If you have diabetes, inspect your feet daily and have any wound checked early
When to See a Doctor
See a doctor if a foot infection is not improving with over-the-counter treatment, or if you have diabetes or poor circulation and notice any foot infection or wound. Seek urgent or emergency care if you have:
- Spreading redness, severe pain, or swelling
- Fever, chills, or red streaks running up the leg
- Pus or foul-smelling drainage, or a wound that is rapidly worsening
- An infected wound in a foot with diabetes or numbness
Prompt treatment can prevent a minor infection from becoming a serious, deep one.
Frequently Asked Questions
What are the most common foot infections?
The most common are fungal infections such as athlete's foot and fungal nail infections, and bacterial infections such as cellulitis and infected wounds. They range from mild and easily treated to serious deep infections.
How are foot infections treated?
Fungal infections are treated with antifungal creams, powders, or oral medicine, while bacterial infections usually need antibiotics. Infected wounds require cleaning and dressing, abscesses may need draining, and serious infections may need hospital care.
Why are foot infections more dangerous for people with diabetes?
Diabetes can cause nerve damage that reduces pain and poor circulation that slows healing, so infections are noticed late and spread more easily. Even a small infection can become serious and reach deeper tissues, so people with diabetes should have any foot infection checked promptly.
When should I worry about a foot infection?
Seek urgent care if you have spreading redness, severe pain, swelling, fever, red streaks up the leg, pus, or a wound that is quickly worsening. People with diabetes or poor circulation should seek care for any foot infection or wound.
How can I prevent foot infections?
Keep your feet clean and dry, dry between the toes, wear breathable shoes and clean socks, wear sandals in locker rooms and pools, and treat athlete's foot and small wounds promptly. Daily foot checks are important if you have diabetes.
References
- MedlinePlus, U.S. National Library of Medicine. Foot injuries and disorders.
- Centers for Disease Control and Prevention (CDC). Fungal Diseases — Athlete's foot.
- Mayo Clinic. Cellulitis — Symptoms and causes.
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Diabetes and Foot Problems.