Paronychia
Basics
Description
- Superficial inflammation of the lateral and posterior nail folds surrounding the fingernail or toenail. Develops after breakdown of barrier between nail plate and the adjacent nail fold
- Acute: characterized by pain, erythema, and swelling (1) lasting <6 weeks; usually a bacterial infection appearing after nail biting, trauma, manicures, ingrown nails, and hangnail manipulation. It also occurs as an adverse effect from several drugs. It can progress to abscess formation.
- Chronic: characterized by swelling, tenderness, cuticle elevation, and nail dystrophy and separation lasting at least 6 weeks, or recurrent episodes of acute eponychial inflammation and drainage
- Chemotherapy-associated paronychia (CAP) starts 4 to 8 weeks after chemotherapy initiation (2).
- May be considered work-related among bartenders, restaurant servers, dishwashers, nurses, and others who often wash their hands
- Usually involves one finger but drug-induced paronychia may involve multiple fingers
- Relevant anatomy: nail bed, nail plate, and perionychium
- Synonym(s): eponychia, perionychia, retronychia
Pediatric Considerations
Less common in pediatric age groups; commonly caused by trauma to periungual skin, such as thumb/finger-sucking or other injuries (Staphylococcus aureus and group A Streptococcus may be present). Paronychia is also a frequent adverse effect of BRAF and MEK inhibitor anticancer drugs.
Epidemiology
Incidence
- One of the most common hand infections in the United States
- Predominant age: all ages
- Predominant sex: female > male
Etiology and Pathophysiology
- Acute: mixed aerobic and anaerobic bacterial flora in 50% of cases. Staphylococcus aureus most common and Streptococcus pyogenes; less frequently, Pseudomonas aeruginosa and other gram-negative bacteria (with chronic paronychia)
- Chronic: eczematous reaction with secondary Candida albicans (~95%)
- Pediatric age groups: mixed anaerobic (Fusobacterium, Peptostreptococcus) and aerobic infections (Eikenella corrodens, S. aureus, streptococci) from oral flora
- A paronychial infection commonly starts in the lateral nail fold.
- Acute paronychia of the fingers is often due to trauma; acute paronychia of the toes is often due to ingrown nails (3).
- Recurrent inflammation, persistent edema, and fibrosis of nail folds cause nail folds to round up and retract, exposing nail grooves to irritants, allergens, and pathogens.
- Inflammation compromises ability of proximal nail fold to regenerate cuticle leading to decreased vascular supply. This can cause decrease efficacy of topical medications.
- Early in the course, cellulitis alone may be present.
- An abscess can form if the infection does not resolve quickly.
Risk Factors
- Acute: direct or indirect trauma to cuticle or nail fold, manicured/sculptured nails, nail biting, thumb sucking, manipulating a hangnail, ingrown toenail
- Chronic: frequent immersion of hands in water with excoriation of the lateral nail fold (e.g., chefs, bartenders, housekeepers, swimmers, dishwashers, nurses)
- Predisposing conditions such as diabetes mellitus (DM) and immunosuppression
- Medications such as EGFR inhibitors, systemic retinoids, chemotherapy, and antiretroviral agents
General Prevention
- Acute: Avoid trauma such as nail biting or manipulating a hangnail. Prevent ingrown toenails.
- Chronic: Avoid exposure to allergens and contact irritants; keep fingers/hands dry; wear rubber gloves with a cotton liner. Prevent excoriation of the skin.
- Keep nails short; avoid manicures.
- Apply moisturizer after washing hands.
Commonly Associated Conditions
DM, eczema or atopic dermatitis, immunosuppression
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Citation
Domino, Frank J., et al., editors. "Paronychia." 5-Minute Clinical Consult, 33rd ed., Wolters Kluwer, 2025. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116435/all/Paronychia.
Paronychia. In: Domino FJF, Baldor RAR, Golding JJ, et al, eds. 5-Minute Clinical Consult. Wolters Kluwer; 2025. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116435/all/Paronychia. Accessed October 10, 2024.
Paronychia. (2025). In Domino, F. J., Baldor, R. A., Golding, J., & Stephens, M. B. (Eds.), 5-Minute Clinical Consult (33rd ed.). Wolters Kluwer. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116435/all/Paronychia
Paronychia [Internet]. In: Domino FJF, Baldor RAR, Golding JJ, Stephens MBM, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2025. [cited 2024 October 10]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/116435/all/Paronychia.
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