Patients usually develop a burning, pruritic sensation before the infection erupts. A physical exam shows vesicles and vesicopustules, along with pain and erythema. It is important to not confuse this with a felon or a paronychia as incision and drainage of herpetic whitlow could result in a secondary bacterial infection and failure to heal. Onychomycosis is a fungal infection of the nail that causes whitish-yellowish discoloration. Sometimes, it is difficult to treat and requires oral antibiotics instead of topical. Nail psoriasis  can affect the fingernails and toenails. It may cause thickening of the nails with areas of pitting, ridges, irregular contour, and even raising of the nail from the nail bed. Squamous-cell carcinoma is mainly cancer of the skin, but can also affect the nail bed. It is a rare malignant subungual tumor subject to misdiagnosis as chronic paronychia. Treatment
When no pus is present, warm soaks for acute paronychia are reasonable, though evidence to support its use is lacking.Chronic paronychia is treated by avoiding whatever is causing it, a topical antifungal, and a topical steroid. In those who do not improve following these measures, oral antifungals and steroids may be used or the nail fold may be removed surgically. Antibiotics
No strong evidence has been found to recommend topical vs. oral antibiotics, and this may be physician-dependent based on experience. Antibiotics used should have S. aureus coverage. Topical antibiotics used may be a triple antibiotic ointment, bacitracin, or mupirocin.
If the infection is continuous, the cause is often fungal and needs antifungal cream or paint to be treated.Risk factors include repeatedly washing hands and trauma to the cuticle such as may occur from repeated nail biting. or hangnails. In the context of bartending, it is known as "bar rot".Prosectors paronychia is a primary inoculation of tuberculosis of the skin and nails, named after its association with prosectors, who prepare specimens for dissection. Paronychia around the entire nail is sometimes referred to as "runaround paronychia".Painful paronychia in association with a scaly, erythematous, keratotic rash (papules and plaques) of the ears, nose, fingers, and toes may be indicative of acrokeratosis paraneoplastica, which is associated with squamous-cell carcinoma of the larynx.Paronychia can occur with diabetes, drug-induced immunosuppression, or systemic diseases such as pemphigus. Diagnosis
Types
Paronychia may be divided as occurring suddenly, acute, or gradually, chronic. Acute
Acute paronychia is an infection of the folds of tissue surrounding the nail of a finger or, less commonly, a toe, lasting less than six weeks. The infection generally starts in the paronychium at the side of the nail, with local redness, swelling, and pain. : 660  Acute paronychia is usually caused by direct or indirect trauma to the cuticle or nail fold, and may be from relatively minor events, such as dishwashing, an injury from a splinter or thorn, nail biting, biting or picking at a hangnail, finger sucking, an ingrown nail, or manicure procedures.