Paronychia is an infection of the perionychium, or the skin that hangs over the side of the nail. It is the most common hand infection in the United States. Paronychia is seen frequently in children as a result of nail biting and finger-sucking. Paronychia is divided into acute paronychia and chronic paronychia depending on the amount of time the infection has been present.
Causes of Paronychia
Both acute and chronic infections start with a break in the epidermis. An acute infection is associated with trauma to the skin such as a hangnail, ingrown nail, or nail-biting. The most common bacteria responsible is Staphylococcus aureus. Other bacteria that are less commonly involved are Streptococcus species and Pseudomonas species. A chronic infection is associated with repeated irritation such as exposure to detergents and water. Most chronic infections are caused by Candida albicans or other fungi.
Appearance of Acute Paronychia
Acute paronychia starts as a red, warm, painful swelling of the skin around the nail. This may progress to the formation of pus that separates the skin from the nail. Lymph nodes in the elbow and armpit may swell.
Appearance of Chronic Paronychia
In chronic paronychia, the redness and tenderness are less noticeable than the acute infection. The skin around the nail can get boggy. The nail may have a green discoloration due to Pseudomonas infection.
Diagnosis of Paronychia
Paronychia is diagnosed based on clinical symptoms. Sometimes if there is pus involved, a culture may be taken to determine the bacteria involved. This is not absolutely necessary since the bacteria can usually be assumed to be a Staphylococcus or Streptococcus species. Chronic paronychia is more difficult to diagnose. A potassium hydroxide (KOH) test of a smear from the nail fold can sometimes reveal a fungus.
Treatment of Paronychia
Warm soaks can be used 3 or 4 times a day for acute paronychia to promote drainage and relieve some of the pain. Most cases of acute paronychia should be treated with antibiotics such as cephalexin or dicloxacillin. Topical antibiotics or anti-bacterial ointments do not effectively treat paronychia. If there is pus or an abscess involved, the infection may need to be incised and drained. Rarely, a portion of the nail may need to be removed.
Chronic paronychia is treated with topical antifungal medication such as ketoconazole cream. A mild topical steroid like hydrocortisone may be added to the antifungal medication to help reduce inflammation. Steroids should never be used alone on a chronic paronychia.
Special Cases and Paronychia
People with the following conditions tend to have more extensive infections and may need to be treated with a prolonged course of antibiotics.
- A compromised immune system such as from AIDS or long-term corticosteroid use
- Poor circulation in the extremities
Prevention of Paronychia
The following are some guidelines to help prevent paronychia:
- Do not bite nails or cuticles
- Do not suck fingers
- Try to avoid soaking hands in water without wearing waterproof gloves