Paronychia is an inflammation of the folds of tissue surrounding the nail; proximal and/or lateral nail folds. Acute paronychia is mainly due to bacterial infection, Staphyloccus aureus or Streptococcus sometimes viral infection (herpetic whitlow). Chronic paronychia is the result of numerous conditions in which the main factor is the disappearance of the cuticle. On fingers, etiology is often a contact dermatitis; bacterial or mycological infections are secondary colonizations. Onychomycosis due to moulds (Fusarium) or dematiae (Scytalidium dimitiadum) are often associated with paronychia. Paronychia is a frequent side-effect of chemotherapies and targeted therapies. Paronychia is a common complication of lateral or proximal (retronychia) ingrown nail and systemic antibiotics are ineffective unless infection is proved. Do not use systematically systemic antibiotics.