Definition and Classification
Paronychia is an inflammation of the nail folds (the tissue surrounding the nail) that can affect fingers or toes. 2, 3 It is classified into two distinct types based on duration:
- Acute paronychia develops rapidly following trauma to the protective nail barrier and is primarily an infectious process caused by polymicrobial bacteria (commonly Staphylococcus aureus or Streptococcus). 2, 3
- Chronic paronychia is characterized by symptoms lasting at least 6 weeks and represents an irritant contact dermatitis rather than a primarily infectious process, though secondary bacterial or fungal colonization occurs in up to 25% of cases. 1, 2
Key Distinguishing Features
The most commonly affected digits are the thumbs and great toes, likely due to repeated trauma. 1
For acute paronychia, look for:
- Recent history of trauma (nail biting, manicure injury, hangnail removal, or finger-sucking in children) 2, 3
- Rapid onset of painful swelling, erythema, and warmth of the proximal or lateral nail fold 2
- Possible abscess formation with purulent drainage 1, 2
For chronic paronychia, look for:
- Occupational exposure to moisture or chemicals (housekeepers, dishwashers, bartenders, florists, bakers, swimmers) 1, 2
- Loss of the cuticle with detachment from the nail plate 4
- Gradual onset of nail fold swelling with secondary nail dystrophy (thickening, ridging, discoloration) 4
- Symptoms persisting for 6 weeks or longer 1, 2
Important Clinical Pitfall
Do not confuse paronychia with Candida nail infection (candidal onychomycosis), which is a distinct entity. While chronic paronychia may have secondary Candida colonization, true candidal onychomycosis presents differently with nail plate invasion, accounts for only 5-10% of all nail fungal infections, and predominantly affects fingernails in women with wet occupations. 4 Candidal paronychia specifically refers to Candida infection starting in the nail folds with subsequent nail plate involvement, showing white, green, or black marks in the nail and painful movement—unlike dermatophyte infections. 4