Paronychia
Paronychia is inflammation/infection of the nail folds (proximal, lateral, or both) of the fingers or toes, and is one of the most common hand infections seen in emergency and primary care settings…
Dr. Lucas Mastropaolo
Paronychia is inflammation/infection of the nail folds (proximal, lateral, or both) of the fingers or toes, and is one of the most common hand infections seen in emergency and primary care settings. [1-2] It is classified as acute (<6 weeks, typically bacterial) or chronic (≥6 weeks, multifactorial irritant dermatitis). [1][3]
1. History
- Onset and duration: Acute (<6 weeks) vs. chronic (≥6 weeks) — this distinction drives management [1]
- Precipitating event: Nail biting, hangnail picking, manicure/pedicure, splinter, ingrown nail, cuticle trauma [2-3]
- Symptom characterization: Pain, swelling, erythema, warmth localized to the nail fold; ask about purulent drainage or fluctuance
- Timing: Rapid onset (hours to days) suggests acute bacterial; insidious onset over weeks suggests chronic or fungal [1]
- Occupational exposures: Prolonged wet work (dishwashers, bartenders, florists, bakers, swimmers) — key for chronic paronychia [1]
- Important negatives: No vesicular lesions (rules out herpetic whitlow), no volar pulp involvement (rules out felon), no pain with passive extension of the digit (rules out flexor tenosynovitis) [4-5]
2. Alarm Features
- Spreading cellulitis or lymphangitis/lymphadenopathy — signs of regional spread [6]
- Fusiform ("sausage") swelling of the digit with pain on passive extension → suspect pyogenic flexor tenosynovitis (Kanavel signs) — surgical emergency [4-5]
- Volar pulp involvement → suspect felon, which requires separate drainage approach [7]
- Failure to improve after adequate drainage and antibiotics → consider osteomyelitis of the distal phalanx, especially in diabetics [8]
- Systemic signs: Fever, rigors, sepsis — rare but mandate urgent escalation [6]
- Immunocompromised patients (diabetes, HIV, chemotherapy) — higher risk of rapid progression and atypical organisms [1]
3. Medications
- Medication contributors:
- Common treatments:
- Mild/early: Warm soaks ± Burow solution or 1% acetic acid, topical antibiotics (mupirocin) [1]
- Moderate: Oral antibiotics — first-line: TMP-SMX or cephalexin for MSSA coverage; clindamycin if MRSA concern [1][4]
- Chronic: Topical steroids (clobetasol) are more effective than systemic antifungals; topical antifungals as adjunct [3]
- Contraindicated: Avoid incision and drainage for herpetic whitlow (can cause viral dissemination and bacterial superinfection) [4]
- Caution: Oral antibiotics are usually unnecessary if adequate drainage is achieved, unless immunocompromised or severe infection [1]
4. Diet
- No specific dietary triggers for acute paronychia
- For chronic paronychia, minimize prolonged wet exposure during food preparation — wear cotton-lined gloves [1]
- Adequate nutrition and glycemic control in diabetics support wound healing
5. Review of Systems
- Constitutional: Fever, chills (suggests systemic spread)
- Skin: Other skin lesions, vesicles (herpetic whitlow), rashes (psoriasis, eczema — associated with chronic paronychia)
- MSK: Pain with finger flexion/extension, joint stiffness (tenosynovitis)
- Endocrine: Diabetes symptoms (polyuria, polydipsia) — risk factor for complicated infections
- Immune: HIV risk factors, immunosuppressive medications, recent chemotherapy [9]
6. Collateral History and Family History
- Occupational history is critical — wet work, chemical exposure, food handling [1]
- Habits: Nail biting (onychophagia), thumb/finger sucking (especially in children — 24% of antibiotic-resistant cases) [12]
- Family history: Psoriasis, eczema, autoimmune conditions (associated with chronic nail changes)
- Social context: Manicure/pedicure history, shared nail instruments (infection risk)
7. Risk Factors
- Nail trauma: Nail biting, hangnail picking, aggressive manicures — most common precipitant [2-3]
- Wet work/chemical exposure: Housekeepers, dishwashers, bartenders, florists, bakers, swimmers [1]
- Diabetes mellitus — impaired immune function and tissue perfusion [8]
- Immunosuppression: HIV, organ transplant, chemotherapy [1]
- Medications: EGFR inhibitors, retinoids [9-10]
- Ingrown nails (especially toes)
- Peripheral vascular disease
8. Differential Diagnosis
- Herpetic whitlow: Vesicular lesions, grouped on erythematous base; may have prodromal tingling; Tzanck smear shows multinucleated giant cells — do NOT incise [4][12]
- Felon: Infection of the volar pulp space (not the nail fold); tense, painful fingertip pad [5][7]
- Pyogenic flexor tenosynovitis: Kanavel signs (fusiform swelling, flexed posture, tenderness along tendon sheath, pain with passive extension) — surgical emergency [4]
- Subungual melanoma/SCC: Chronic, non-healing periungual lesion unresponsive to treatment — biopsy indicated [2]
- Psoriatic nail disease: Pitting, onycholysis, oil-drop sign
- Osteomyelitis of distal phalanx: Persistent pain despite treatment, fistulous tracts — especially in diabetics [8]
- Pemphigus vulgaris: Rare cause of antibiotic-resistant paronychia [12]
- Contact dermatitis: Chronic irritant exposure mimicking chronic paronychia
9. Past Medical History
- Diabetes — most important comorbidity increasing complication risk [8]
- Immunosuppression (HIV, transplant, chemotherapy)
- Previous episodes of paronychia — recurrence is common
- Peripheral vascular disease — impaired healing
- Dermatologic conditions: Psoriasis, eczema
- Current cancer treatment — EGFR inhibitors, taxanes [9-10]
- Tetanus immunization status — update if indicated [5]
10. Physical Exam
- Inspection: Erythema, swelling, and tenderness of the lateral or proximal nail fold; look for purulent drainage or fluctuance [1][3]
- Palpation: Gently press on the nail fold — fluctuance indicates abscess requiring drainage [1]
- Assess for "runaround" abscess: Infection extending from one nail fold to the other (eponychia) — may require more extensive drainage [7]
- Check volar pulp: If tense and tender → felon, not paronychia [7]
- Kanavel signs: Fusiform swelling, flexed posture, tenderness along flexor sheath, pain with passive extension → flexor tenosynovitis [4]
- Vesicles: Grouped vesicles suggest herpetic whitlow [4]
- Lymphadenopathy: Epitrochlear or axillary nodes suggest spreading infection [6]
- Nail changes (chronic): Thickening, ridging, discoloration, onycholysis [11]
11. Lab Studies
- Routine labs are generally NOT needed for uncomplicated paronychia [1]
- Wound culture: Obtain if abscess is drained, immunocompromised patient, or failure of empiric therapy — most common pathogen is S. aureus; polymicrobial infections are common [1][9]
- CBC, CRP: Consider if systemic signs (fever, lymphangitis) or concern for deep space infection [6]
- Glucose/HbA1c: If diabetes suspected or known — glycemic control affects healing
- Tzanck smear: If vesicles present — multinucleated giant cells confirm HSV (herpetic whitlow) [12]
- KOH prep/fungal culture: For chronic paronychia — Candida is the most common fungal pathogen [3]
12. Imaging
- First-line: X-ray of the digit — indicated if concern for foreign body, osteomyelitis, or fracture [6][8]
- Ultrasound: Point-of-care ultrasound can help identify and localize a small abscess when clinical exam is equivocal [7]
- MRI: Gold standard for suspected osteomyelitis — highest sensitivity; consider when paronychia fails to respond to appropriate treatment [8]
- Imaging is unnecessary for straightforward, uncomplicated acute paronychia [1]
13. Special Tests
- Digital block: Essential for adequate drainage — use a digital nerve block (ring block or single-injection volar technique) with lidocaine without epinephrine (though evidence supports epinephrine safety in digital blocks) [7]
- Tzanck smear: Useful for antibiotic-resistant paronychia — 93% had diagnostic cytologic findings in one series [12]
- Nail plate elevation: If pus is suspected beneath the nail plate, partial or complete nail removal may be needed for adequate drainage [1][7]
- Biopsy: For chronic, non-healing paronychia unresponsive to therapy — rule out malignancy (SCC, melanoma) [2]
14. ECG
- Not applicable for uncomplicated paronychia
- Consider ECG only if systemic sepsis is suspected (rare)
15. Assessment
Acute paronychia is a superficial infection of the nail fold, most commonly caused by S. aureus and polymicrobial flora, precipitated by disruption of the nail barrier. [1][11] Severity ranges from mild cellulitis to frank abscess formation. Chronic paronychia (≥6 weeks) is primarily an irritant dermatitis rather than a primary infection, though secondary colonization with Candida and bacteria is common. [1][3]
Key clinical pearls:
- The most common mistake is treating herpetic whitlow as bacterial paronychia — look for vesicles and avoid I&D [4][12]
- Chronic paronychia unresponsive to treatment should raise concern for malignancy or osteomyelitis [2][8]
- Drug-induced paronychia (EGFR inhibitors) may require partial matricectomy if unresponsive to conservative therapy by 3 months [10]
16. Treatment Plan
Acute Paronychia — Stepwise Approach
- Mild (no abscess): Warm soaks 3–4 times daily for 15 minutes ± Burow solution or 1% acetic acid; topical antibiotic (mupirocin) ± topical steroid [1][3]
- Moderate (early abscess/cellulitis): Add oral antibiotics — cephalexin 500 mg QID or TMP-SMX DS BID (if MRSA concern) for 5–7 days; continue warm soaks [1][4]
- Abscess present — I&D is mandatory: [1][7]
- Perform digital block
- Simple paronychia: Lift the nail fold off the nail plate using a #11 blade or 18-gauge needle along the nail fold — allow pus to drain
- Eponychia/runaround abscess: Single or double incision technique along the nail margin [7]
- Subungual extension: Partial or complete nail removal to allow drainage [1][7]
- Pack loosely with iodoform gauze; remove packing in 24–48 hours
- Oral antibiotics are usually not needed post-drainage unless immunocompromised or severe infection [1]
Chronic Paronychia
- Eliminate irritant exposure — avoid wet work, wear cotton-lined rubber gloves [1]
- Topical steroids (clobetasol) are first-line — more effective than systemic antifungals [3]
- Topical antifungal (clotrimazole, ketoconazole) as adjunct [3]
- Emollients to restore nail barrier [3]
- Refractory cases: Eponychial marsupialization or en bloc excision of the proximal nail fold; partial matricectomy for drug-induced cases [3][10]
17. Disposition
- Discharge: Vast majority — uncomplicated paronychia is managed outpatient [1][7]
- Observation/Admission criteria:
- Systemic signs of infection (fever, sepsis)
- Suspected deep space infection or flexor tenosynovitis → urgent hand surgery consult [4]
- Immunocompromised with rapidly progressing infection
- Failed outpatient management with worsening despite I&D and antibiotics
- Specialist consultation triggers:
18. Follow Up / Return Precautions
- Follow-up: 48 hours for wound check and packing removal after I&D; 1 week for reassessment [1]
- Return immediately for:
- Worsening redness, swelling, or pain despite treatment
- Red streaking up the hand/arm (lymphangitis)
- Fever or chills
- Inability to bend or straighten the finger (concern for tenosynovitis)
- Numbness or color change in the fingertip
- Patient counseling:
- Expected recovery: Acute paronychia typically resolves within 5–10 days with appropriate treatment; chronic paronychia may take weeks to months [1]
- Tetanus prophylaxis: Update if not current and wound is at risk [5]
References
1. Acute and Chronic Paronychia. — Leggit JC. American Family Physician. 2017.
2. Acute and Chronic Paronychia. — Rockwell PG. American Family Physician. 2001.
3. Acute and Chronic Paronychia. — Rigopoulos D, Larios G, Gregoriou S, Alevizos A. American Family Physician. 2008.
4. Acute Hand Infections. — Rerucha CM, Ewing JT, Oppenlander KE, Cowan WC. American Family Physician. 2019.
5. Common Acute Hand Infections. — Clark DC. American Family Physician. 2003.
6. Diagnosis and Management of Upper Limb Soft Tissue Infections. — Auquit-Auckbur I, Beccari R, Coquerel-Beghin D, Garcia-Doldan CM. Orthopaedics & Traumatology, Surgery & Research : OTSR. 2025.
7. Management of Finger Felons and Paronychia: A Narrative Review. — Gottlieb M, Long B. The Journal of Emergency Medicine. 2025.
8. Osteomyelitis Mimicking Chronic Paronychia. — Signoret-Bravo MT, Berumen-Glinz C, Gatica-Torres M, Michel-Izeta BE, Domínguez-Cherit J. JAMA Dermatology. 2026.
9. Nail Toxicities Induced by Systemic Anticancer Treatments. — Robert C, Sibaud V, Mateus C, et al. The Lancet. Oncology. 2015.
10. Surgical Intervention for Paronychia Induced by Targeted Anticancer Therapies. — Hanania HL, Pacha O, Heberton M, Patel AB. Dermatologic Surgery : Official Publication for American Society for Dermatologic Surgery. 2021.
11. Acute and Chronic Paronychia of the Hand. — Shafritz AB, Coppage JM. The Journal of the American Academy of Orthopaedic Surgeons. 2014.
12. Clinical and Cytologic Features of Antibiotic-Resistant Acute Paronychia. — Durdu M, Ruocco V. Journal of the American Academy of Dermatology. 2014.