Paronychia is an infection of the skin around the nail of at least one finger or toe, which can be caused by bacteria or fungi. It can be classified as either acute or chronic, with chronic paronychia being present for longer than six weeks. Chronic paronychia results from irritant dermatitis rather than an infection, and common irritants include acids, alkalis, or other chemicals commonly used by housekeepers, dishwashers, bartenders, laundry workers, florists, bakers, and swimmers. Once the protective nail barrier is disrupted, repeated exposure to irritants may result in chronic inflammation. Fungal infections are thought to represent colonization, not a true pathogen, so antifungals are generally not used to treat chronic paronychia. Several classes of medications can cause chronic paronychia, including retinoids, protease inhibitors, antiepidermal growth factor receptor antibodies, and several classes of chemotherapeutic agents.
Treatment of chronic paronychia consists of stopping the source of irritation, controlling inflammation, and restoring the natural protective barrier. Topical anti-inflammatory agents, steroids, or calcineurin inhibitors are the mainstay of therapy. In a randomized, unblinded, comparative study, tacrolimus 0.1% (Protopic) was more effective than betamethasone 17-valerate 0.1% . In severe or refractory cases, more aggressive treatments may be required to stop the infection. Treatment of acute paronychia is determined by the degree of inflammation, and if an abscess has not formed, the use of warm water compresses and soaking the affected digit in Burows solution or vinegar may be effective. Acetaminophen or a nonsteroidal anti-inflammatory drug should be considered for symptomatic relief. Chronic paronychia can be treated with a broad-spectrum topical antifungal agent to prevent recurrence. Application of emollient lotions to lubricate the nascent cuticle and the hands is usually beneficial. One randomized controlled trial assigned 45 adults with chronic paronychia to treatment with a systemic antifungal agent or a topical steroid cream, and both treatments were found to be effective.
Less common causative agents of paronychia include gram-negative organisms, dermatophytes, herpes simplex virus, and yeast. Chronic paronychia is caused primarily by the yeast fungus Candida albicans, and other rare causes of chronic paronychia include bacterial, mycobacterial, or viral infection, metastatic cancer, subungual melanoma, and squamous cell carcinoma. Therefore, benign and malignant neoplasms should always be excluded when chronic paronychia does not respond to conventional treatment. Chronic paronychia most often occurs in persons whose hands are repeatedly exposed to irritants and allergens, and treatment should point towar...
