Common Infections of the Foot

Your feet are always in contact with infection-causing fungus and bacteria. That's true no matter how clean they are.

Usually, your immune system keeps them at bay. But you're vulnerable to infection when:

• Your immune defenses are low
• A pathogen (infection-causing organism) is especially robust
• A break in your skin gives a pathogen easy access

Foot infections are often mild. You can treat them at home. Others need more aggressive treatment. Some can even land you in the hospital with serious complications.

You're better off preventing infection than treating it. This article looks at common fungal and bacterial infections, how to recognize them, and how to avoid them.

Fungal Foot Infections

You can pick up foot or toenail infections in a locker room or spa. Fungi are especially hearty. They can thrive even on intact skin.

The foot, especially between the toes, is an ideal environment for infection. The roots of the fungus can penetrate damp, softened tissues. Your foot just touches a moist, contaminated surface and you're infected.

Fungal foot infections can be persistent and hard to treat. But they're rarely life-threatening.

Athlete's Foot (Tinea Pedis)

Have an itchy, flaky rash between your toes? It's likely athlete's foot (tinea pedis). This infection is caused by several fungi, including those linked to ringworm.

Fungus loves moist environments—gyms, saunas, and sweaty socks and shoes. It's highly contagious. Contaminated floors, towels, or clothing spread it easily.

Most cases can be diagnosed by symptoms alone. More serious or recurrent cases may warrant examination of a skin scraping. This is known as a KOH test.

Mild cases can be treated with an over-the-counter (OTC) antifungal cream or spray.

Serious or persistent infections may require an oral antifungal medication. You may be put on Lamisil (terbinafine) or Sporanox (itraconazole) for up to six months.

Toenail Fungus (Onychomycosis)

A common, slow-growing fungal infection under the toenail is called onychomycosis. Symptoms include:

• White or yellow nail discoloration
• Thickened, flaky nails
• Separation of the nail from the nail bed

Onychomycosis often accompanies athlete's foot. It's more common in people with a weakened immune system or peripheral vascular disease (which impairs blood flow to the feet).

It can be diagnosed on sight. Your healthcare provider may order a KOH test to confirm that. Tissue cultures from nail trimmings can identify the specific fungus.

Onychomycosis is notoriously difficult to treat. That's partly because topical creams can't penetrate the nail tissue.

Oral antifungal treatment tends to work best. But it can take up to 12 months for a nail to fully grow back.

Terbinafine is considered the treatment of choice. It's often given alongside itraconazole.

Bacterial Foot Infections

Bacterial foot infections are less common than fungal infections. But they sometimes turn serious. A foot infection can lead to a systemic (whole-body) one.

Most bacterial infections start in sores or abrasions. For example, they can take hold in an ingrown toenail (onychocryptosis).

Even eczema, athlete's foot, or severe sunburn can provide an opportunity for infection. All it takes is a broken outer layer of skin (epidermis).

Anyone can have a bacterial foot infection. But your complication risk may be high due to:

• Aging
• Diabetes (poor blood circulation plus a lowered ability to fight infection)
• A compromised immune system (untreated HIV, immunosuppressant drugs, chemotherapy)

Bacterial infection causes red, swollen, painful skin and possibly yellow or green pus. The most common culprit is Staphylococcus aureus (staph infection). However, other types are more common in specific conditions.

Erythrasma

Erythrasma is a bacterial infection frequently mistaken for a fungus. It's caused by Corynebacterium minutissimum. And it's most common in people with diabetes or obesity.

As with fungi, the bacteria take hold in folds of skin such as:

• Armpits
• Under the breasts
• In the groin
• Between the toes

On light skin, the patches may first look pink or red. They could be harder to see on dark skin. Then they quickly turn brown and scaly as your skin flakes and sheds.

Erythrasma is often diagnosed with an ultraviolet light called a Wood's lamp. It makes the bacteria glow coral-pink.

This infection is best treated with a topical fusidic acid cream or an oral antibiotic such as Zithromax (azithromycin) or Erythrocin (erythromycin).

Foot Abscess

Bacterial foot infections sometimes go beyond the outer layers of tissue. Then they form a pocket of pus known as an abscess.

Foot abscesses are often caused by puncture wounds or hair follicle infections. They're similar to boils but involve deeper tissues.

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Abscess symptoms include:

• Redness
• Swelling
• Warmth
• Pain
• A raised bump that can spontaneously erupt
• Low-grade fever
• General achiness

S. aureus is often to blame. But if it's confined to the feet, Fusobacterium necrophorum and Arcanobacterium pyogenes are more likely.

Abscesses are often diagnosed with a physical exam. Your healthcare provider may order a bacterial culture in order to find the best antibiotic to kill it.

Treatment usually involves draining the abscess plus oral and/or topical antibiotics for the infection. An OTC painkiller like Tylenol (acetaminophen) can reduce pain and fever.

Cellulitis

Cellulitis is a potentially serious skin complication. It starts with an injury that gets infected. The the infection spreads.

Cellulitis typically starts as a small area of inflammation that quickly spreads to surrounding tissues. It causes:

• Swelling
• Pain
• Warmth
• Red streaks moving upward from the foot

The red streaks (lymphangitis) are from the infection migrating toward your lymph nodes. If it gets there, the infection can become systemic. It can even be life-threatening. Signs of a serious infection include:

• High fever
• Chills
• Body aches

Cellulitis is typically caused by a break in the skin. It's especially common in people with diabetes or poor blood circulation. S. aureus and Streptococcus are the most likely causes.

Simple cases may be treated with broad-spectrum antibiotics for between five and 14 days. Serious cases may require hospitalization with intravenous (IV) antibiotics and fluids.

Prevention

You can prevent foot infections by:

• Keeping your feet clean and dry
• Washing daily with soap and water
• Not going barefoot in public spaces
• Not sharing footwear or nail clippers
  
• Keeping your toenails trimmed
• Regularly changing your socks and shoes to prevent moisture build-up

If your feet are especially sweaty or prone to fungal infection, use a daily OTC antifungal foot powder or spray.

If the skin on your foot is cut or scraped, wash it immediately with soap and water. Then cover it with a sterile bandage.

If your foot is prone to dryness and cracking, use a petrolatum-based foot cream to soften the skin.

Summary

Fungal foot infections include athlete's food and onychomycosis (toenail fungus). They're easy to spread and treated with antifungal creams, sprays, or oral medications.

Bacterial foot infections include erythrasma, abscesses, and cellulitis. Oral or topical antibiotics can clear them up.

To prevent infections, treat foot injuries immediately. Keep skin healthy and intact. You can use anti-fungal products daily as prevention. Don't use antibiotics this way or it could cause drug-resistant bacteria.

A Word From Verywell

Foot infections should be taken seriously. At their best, they're uncomfortable. At their worst, they can be deadly.

Most fall somewhere in between. Getting a diagnosis and proper treatment can make a big difference in how serious the infection gets.

So protect your health by seeing a healthcare provider any time you suspect a foot infection. And remember that red streaks should send you straight to the emergency room.