Nail Infection (Paronychia): Everything You Need to Know

Paronychia is a type of nail infection, most commonly caused by the bacteria called Staphylococcus aureus, which affects the skin around the nail (called nail folds). It can also occur as a result of a fungal nail infection, referred to as onychomycosis. Symptoms include redness, swelling, pain, and pus discharge.

Topical antibiotics may be needed to clear the bacteria infection. If a nail fungus is involved, a topical antifungal may be prescribed. While most cases are mild and will resolve on their own, some can turn severe and lead to complications like cellulitis.

This article looks at the causes and symptoms of paronychia, including what it looks like and how it is diagnosed and treated. It also describes ways to prevent nail infections and when to see a healthcare provider.

Types of Nail Infections

Paronychia is the inflammation of the nail folds, namely the lateral nail folds on either side of the nail and the proximal nail fold adjacent to the cuticle (the layer of skin at the base of the nail). The nail plate and nail bed can also be collaterally damaged.

Paronychia can be acute (sudden and severe) or chronic (persistent or recurrent). Acute cases almost invariably involve bacteria, while chronic cases are typically associated with fungi or chemical irritants.

By definition, acute infections are those that last less than six weeks, while chronic infections are those that persist or recur for more than six weeks.

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Bacterial Nail Infections

Paronychia is primarily bacterial in origin. While Staphylococcus aureus is the main culprit, other bacteria like Pseudomonas aeruginosa and Streptococcus pyogenes (the cause of strep throat) can also cause acute paronychia.

Bacteria can penetrate nail folds in different ways:

• An injury to a finger or toe
• A hangnail that has been pulled out
• Having an ingrown nail
• Biting your nails
• Skin damage caused by a manicure or artificial nails
  

Staphylococcus aureus is a common cause because it is naturally found in high concentrations in the nose as well as on the skin. Streptococcus pyogenes is also found in the nose, mouth, and skin, while Pseudomonas aeruginosa is commonly found in soil and water.

Acute paronychia can cause the formation of a pocket of pus, called an abscess, which may need draining by a healthcare provider.

Fungal Nail Infections

Chronic paronychia is commonly associated with fungal nail infections (known alternately as onychomycosis and tinea unguium).

With onychomycosis, the infection can sometimes spread and colonize the nail folds. Because the infection is notoriously difficult to treat, the swelling can persist and become chronic.

While common fungi like Trichophyton rubrum (associated with athlete's foot) can sometimes cause paronychia, it is most often seen with Candida albicans, the fungus associated with yeast infections and oral thrush.

As with Staphylococcus aureus, Candida albicans is found naturally in the human body. But unlike Staphylococcus aureus, it most often causes disease when a weakened immune system allows the fungus to grow out of control.

As a result, paronychia associated with Candida albicans mainly affects:

• People with compromised immune systems (such as those with HIV or diabetes)
• People who take immunosuppressant drugs
• People who work in occupations like dishwashing or laundering in which their hands are repeatedly saturated with water

What Does a Nail Infection Look Like?

Paronychia is easily recognized and something that most people will experience at one time or another. It mainly affects the nail folds but can also affect the nail bed and nail plate.

Common symptoms include:

• Pain, swelling, and tenderness of the skin surrounding the nail
• Skin that is red and warm to the touch
• Pus discharge and the formation of an abscess under the nail fold

Left untreated, the nail can develop ridges, waves, and yellowish or greenish discoloration. The nail can become dry and brittle and crack or entirely detach from the nail bed. Fingernails are affected more than toenails.

Although it can be difficult to tell if the condition is bacterial or fungal, there are several clues:

Occupational paronychia is more commonly associated with Candida albicans but can sometimes involve the bacteria Pseudomonas aeruginosa which thrives in water.

How Is a Nail Infection (Paronychia) Diagnosed?

Paronychia can be diagnosed by physical examination of the finger or toe. Laboratory tests are generally not needed. Imaging tests, like an X-ray or ultrasound, may be used if there is an abscess, but even this is uncommon unless the abscess is severe or there are other unusual signs.

As part of the physical exam, the provider may perform a digital pressure test in which you are asked to press your thumb and affected finger together. If there is an abscess, the skin overlying the abscess will blanch (whiten).

Pus extracted from an abscess may be cultured to identify the exact bacteria or fungi, but this is usually not helpful. Only around 4% of these cultures can identify a single causal agent; most detect multiple bacterial types.

If your signs or symptoms are atypical, your healthcare provider may order tests to exclude other possible causes as part of the differential diagnosis, including:

• Eczema
• Granuloma annulare
• Herpetic whitlow
• Psoriasis
• Reiter's syndrome (reactive arthritis)
• Squamous cell carcinoma
• Subungual melanoma

Nail Infection (Paronychia) Treatment

Acute paronychia is bacterial in origin and typically treated with home remedies, topical antibiotics, or abscess drainage. Chronic paronychia is treated differently based on its severity and underlying cause.

Home Remedies

Acute paronychia doesn't always require medical treatment. If there is some pus, soaking your finger or toe for 10 to 15 minutes, several times a day can help drain the pus and speed healing.

Some experts recommend adding Epsom salt to the soaking solution, particularly for conditions like ingrown nails, Others endorse the use of vinegar or an over-the-counter (OTC) astringent called Burow's solution, both of which have been used for generations to treat skin infections.

If using apple cider or distilled white vinegar, add 1 tablespoon to 6 cups of water to make a 1% vinegar solution.

Over-the-Counter Drugs

Topical antibiotics are commonly used to treat paronychia. Three over-the-counter (OTC) options may help:

• Bacitracin (bacitracin zinc)
• Neosporin (neomycin/bacitracin zinc/polymyxin B)
• Polysporin (polymyxin B/bacitracin zinc/gramicidin)

All three exert activity against Streptococcus aureus and Streptococcus pyogenes. Polysporin may be especially useful as it also contains a skin-numbing agent called lidocaine.

Follow the instructions on the product label.

Prescription Medications

Prescription antibiotics may be prescribed if home and OTC remedies fail to provide relief.

Topical antibiotics are preferred over oral antibiotics, which have not proven more effective in treating uncomplicated paronychia. If anything, oral antibiotics are associated with a greater risk of antibiotic resistance.

Topical antibiotics your healthcare provider may prescribe include:

• Bactroban (2% mupirocin ointment): Applied two to four times daily for five to 10 days
• Gentamicin 0.1% cream: Applied three to four times daily for five to 10 days
• Topical fluoroquinolones: Including ciprofloxacin, levofloxacin, moxifloxacin, and ofloxacin (dosages vary)

Fluoroquinolones are especially effective against Pseudomonas aeruginosa. A topical steroid like Diprolene (betamethasone 0.05% cream) may also be prescribed to help ease inflammation.

Oral antibiotics are reserved for severe cases that don't respond to topical treatment or for people who are severely immunocompromised.

Oral options include:

• Augmentin (amoxicillin/clavulanic acid)
• Bactrim (trimethoprim/sulfamethoxazole)
• Clindamycin
• Cephalexin
  

Abscess Drainage

In the event of an abscess, medical treatment may be needed to drain the accumulated pus. Drainage should not be done at home as it can lead to a severe infection if not done correctly or with sterile equipment.

Topical lidocaine can be used to help numb the skin, but this is generally not needed.

Once the pus is drained, oral antibiotics are not needed. Instead, you can soak the wound two to three times daily for several days with diluted Burow's solution or a 1% vinegar solution. This is generally all that is needed to promote healing and prevent infection.

Treating Chronic Paronychia

The treatment of chronic paronychia can vary by the severity of symptoms and the underlying cause. Options include:

• Topical steroids: Typically the first-line option, applied twice daily for two to four weeks
• Topical antifungals: Like ciclopirox 0.77%, applied twice daily for one or more months
• Topical 0.1% tacrolimus: A second-line option, applied twice daily for three to four weeks
• Oral antifungals: Like Diflucan (fluconazole), reserved for severe Candida albicans infections
• Intralesional steroid injection: Used for severe inflammation when all other treatments fail
  

How to Prevent Nail Infections (Paronychia)

The risk of acute and chronic paronychia can be greatly reduced by avoiding damage to your nail folds. These measures are especially important if you've had nail infections in the past.

To reduce the risk of paronychia:

• Keep your fingernails short to avoid hangnails. Be sure to use sharp clippers or cutting tools.
• Cut your toenails straight across to prevent ingrown nails. Avoid shoes that are too tight.
• Avoid nail biting, finger sucking, or picking off bits of skin around your nails.
• Do not trim your cuticles. If you push them back during a manicure, do so gently.
• Apply moisturizer after handwashing, especially around the nails, to keep the skin moist and prevent dryness and cracking.
• Avoid prolonged exposure to detergents and other harsh irritants, or wear rubber gloves to protect your hands and keep them dry.

What’s the Outlook for People With Paronychia?

With appropriate treatment, most cases of acute paronychia will quickly resolve without complications. Although chronic paronychia can take weeks to heal, the nail and surrounding skin usually return to normal.

However, if paronychia is not appropriately treated, it can lead to discoloration, ridges, cracks, and the total loss of your nail. Even if the nail does return, it may not ever fully return to normal (referred to as chronic nail dystrophy).

Certain people may develop severe complications if the infection happens to spread. People who are immunocompromised are most commonly affected, including those with advanced untreated diabetes.

Rare complications of paronychia include:

• Cellulitis: This is a potentially serious condition in which a local bacterial infection spreads into deeper tissues. Without antibiotics, the infection can spread even further and become deadly.
• Septic tenosynovitis: This is the spread of infection to underlying tendons, causing fever, joint pain, stiffness, and swelling. Antibiotics are urgently needed to prevent permanent joint damage.
• Osteomyelitis: This is the spread of the infection to underlying bones, causing pain, fever, chills, and the destruction of bone matter. Surgery is often needed to remove and repair dead bone.

When to Contact a Healthcare Provider

As a general rule, you should see a healthcare provider if symptoms of paronychia do not improve with conservative treatment or if you suspect that you have an abscess.

Seek immediate care if there are signs that the infection spreading, including:

• High fever with chills
• Increasing pain, swelling, and heat
• Profuse pus discharge
• Difficulty moving the joint
• Rapidly spreading redness or red streaks
• A glossy, stretched appearance of the skin
• A rapidly developing skin sore near the site of the infection

Summary

Paronychia is an infection of the skin surrounding the nail, called nail folds. Bacteria cause acute infections, while chronic infections are most frequently associated with fungus. Symptoms include redness, pain, warmth, and redness. Left untreated, paronychia can an abscess, nail deformity, and nail loss.

Paronychia is diagnosed with a physical exam. Acute cases may be treated with warm soaks and topical antibiotics. Chronic cases may require topical steroids, antifungals, or tacrolimus. Abscesses should be a healthcare provider to drain the accumulated pus safely.