Paronychia (Nail Infection): Symptoms, Causes, Risks and Treatment

What is Paronychia (Nail Infection)?

Paronychia is an infection of the skin surrounding a fingernail or toenail. Specifically, it affects the nail fold, which is the skin that borders the nail laterally and at its base. This includes the tissue surrounding the nail root. It may develop spontaneously or following trauma or repeated manipulation of the nail and surrounding skin.

Paronychia is one of the most common infections of the hand and is typically limited to a single digit. However, when a systemic cause, like a drug-induced reaction, is responsible, multiple nails may be affected at the same time.

Acute vs. Chronic Paronychia

Clinically, paronychia is classified according to its duration:

• Acute paronychia: Sudden onset, most commonly bacterial in origin. Prognosis is excellent. The condition typically resolves within a few days with appropriate treatment, and the risk of recurrence is very low in otherwise healthy individuals.
• Chronic paronychia: Defined as lasting 6 weeks or longer. It tends to be more persistent, prone to relapse, and is more often associated with fungal infection or repeated environmental irritant exposure. Chronic paronychia predominantly affects individuals with specific predisposing factors (see below).

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Causes

The infection begins where there is a break in the protective barrier between the nail and the nail fold. This typically happens at the cuticle, which is the thin layer of skin at the base of the nail. When this natural barrier is disrupted, microorganisms gain access to the underlying tissues and initiate an infectious and inflammatory process.

Common Predisposing Factors

• Trauma: the most common cause overall

  • Nail biting (onychophagia): Particularly prevalent in children and adolescents; introduces oral bacteria into the nail fold
  • Manicure and pedicure procedures: Aggressive cuticle cutting, pushing, or removal
  • Artificial nails: Mechanical irritation and chemical exposure
  • Foreign bodies: Small splinters or other foreign material, particularly when retained within the skin
  • Finger sucking, especially in young children

• Infections: Bacterial, viral, and fungal organisms may be responsible

• Inflammatory skin diseases: Psoriasis and contact dermatitis can compromise the integrity of the nail fold

• Medications: drug-induced paronychia is a recognized adverse effect of several classes of drugs:

  • Immunosuppressants
  • Oral retinoids (acitretin, isotretinoin), which cause skin dryness and fragility
  • BRAF inhibitors (vemurafenib, dabrafenib): used in targeted cancer therapy
  • Epidermal growth factor receptor (EGFR) inhibitors, a newer oncological drug class, are increasingly associated with nail fold reactions

Causative Microorganisms

• Bacteria: The predominant cause of acute paronychia. Staphylococcus aureus is the most frequently implicated pathogen; other common organisms include Streptococcus pyogenes and oral anaerobes (particularly in cases related to nail biting or finger sucking)
• Viruses: Herpes simplex virus (HSV) can cause a specific form of paronychia known as herpetic whitlow. This is a painful viral nail fold infection that may be confused with bacterial paronychia but requires different treatment
• Fungi: Most commonly Candida species, the predominant causative agent in chronic paronychia, particularly in individuals with prolonged wet hand exposure

Risk Factors

Paronychia is approximately three times more common in women than men, likely reflecting occupational and behavioral factors.

Groups at particularly elevated risk include:

• Workers with prolonged water exposure: Dishwashers, housecleaners, bartenders, fishermen, healthcare workers. Chronic maceration of the skin weakens the cuticle barrier
• Manual laborers: repetitive minor trauma to the hands
• Children: the habit of putting fingers in the mouth introduces oral bacteria and trauma to the nail fold
• Nail biters and cuticle pickers: direct mechanical disruption of the protective barrier
• Immunocompromised patients: Individuals with diabetes mellitus, HIV/AIDS, or those receiving immunosuppressive therapy are at higher risk of chronic, recurrent, and atypical paronychia

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Symptoms

As an inflammatory and infectious process, paronychia presents with the classic signs of local infection, namely the four cardinal signs of inflammation, localized to the nail fold:

• Redness (erythema) of the skin surrounding the nail
• Pain often described as throbbing or pulsating, particularly in acute bacterial cases
• Swelling (edema) of the affected nail fold
• Warmth: the affected area may feel warmer than the surrounding skin

These symptoms may affect the big toe, thumb, or any other digit; fingers and toes are equally susceptible.

Additional Features

• Pus formation (abscess): In some cases, a pocket of pus develops within the nail fold, visible as a yellowish-greenish, creamy collection beneath the skin. Pus is composed of serum, blood, white blood cells, bacteria (living and dead), and cellular debris from the immune response.
• Vesicles (blisters): When herpes simplex virus (HSV) is the causative agent, characteristic small, painful fluid-filled vesicles may be observed in or around the nail fold, a key feature that helps distinguish herpetic whitlow from bacterial paronychia.
• Nail changes: In chronic or severe cases, the nail plate itself may become discolored, ridged, thickened, or separated from the nail bed

Systemic Symptoms (Severe Cases)

In particularly severe infections, especially in immunocompromised patients, systemic manifestations may develop:

• Fever
• Swollen lymph nodes (lymphadenopathy), for example in the axilla (for finger infections) or groin (for toe infections)

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Complications

In otherwise healthy individuals, acute paronychia has an excellent prognosis and follows a benign course with appropriate treatment. However, when left untreated or inadequately managed, particularly in immunocompromised patients, the infection can spread and lead to serious complications:

• Deep space hand infections: Spread of infection to the deeper structures of the finger, including tendons and tendon sheaths (tenosynovitis), which is a surgical emergency
• Osteomyelitis: Extension of infection to the underlying bone, particularly in severe or long-standing cases
• Permanent nail deformity: Chronic inflammation of the nail matrix can disrupt nail plate formation, resulting in permanent ridging, discoloration, or abnormal nail growth
• Sepsis: Extremely rare in immunocompetent individuals, but systemic bacteremia is a potential risk in severely immunocompromised patients

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Diagnosis

The specialist of choice is a dermatologist, though the patient’s general practitioner (GP) or family doctor is fully qualified to evaluate and manage the majority of cases. In children, a pediatrician may be the first point of contact.

Clinical Diagnosis

Diagnosis is primarily clinical, based on direct observation of the lesion combined with a targeted medical history. The characteristic appearance of the infected nail fold is usually sufficient to confirm the diagnosis without the need for laboratory testing.

Key elements of the history include:

• Occupation and hand exposure habits (water, chemicals, animals)
• Nail care habits (manicure, nail biting, artificial nails)
• Trauma or foreign body exposure
• Systemic conditions (diabetes, immunodeficiency)
• Current medications

When Are Additional Tests Needed?

• Routine blood tests and imaging are generally not required for uncomplicated acute paronychia
• Bacterial culture: In selected cases, particularly recurrent, treatment-resistant, or atypically presenting infections, a swab for bacterial culture and antibiotic sensitivity testing can identify the causative organism and guide antibiotic selection
• Fungal culture/microscopy: For suspected chronic fungal paronychia
• Investigation of underlying conditions: In chronic paronychia, it may be appropriate to screen for predisposing conditions (e.g., blood glucose for diabetes, immune function testing)

Differential Diagnosis

Paronychia must be distinguished from several other conditions that may present similarly:

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Treatment

1. Conservative Management (Without Abscess)

In the absence of pus formation, initial management is conservative:

• Warm soaks: Immersing the affected finger or toe in warm water with an antiseptic solution for at least 10–15 minutes, 3–4 times per day is the cornerstone of conservative treatment. Effective antiseptic solutions include:
  • Chlorhexidine: widely available and highly effective
  • Povidone-iodine provides broad-spectrum antimicrobial coverage
  • Chloramine-based solutions (e.g., Euclorina® sachets)

These soaks help reduce bacterial load, promote local blood flow, and may facilitate spontaneous drainage of any early pus collection.

2. Antibiotic Therapy

The decision to prescribe antibiotics, and which type, must be made by a physician following clinical evaluation. Antibiotic therapy is not always necessary and should not be self-initiated. The physician will determine:

• Whether antibiotics are needed at all (mild cases may resolve with soaks alone)
• Route of administration:
  • Topical antibiotics (creams or ointments) for mild to moderate cases without systemic involvement, for example mupirocin (e.g., Bactroban® cream)
  • Oral antibiotics for more severe, spreading, or systemic cases, e.g., amoxicillin-clavulanate (Augmentin® tablets), which covers Staphylococcus aureus and oral anaerobes

Important reminder: Antibiotic therapy is not always necessary and should only be initiated upon explicit medical advice. Inappropriate antibiotic use contributes to antimicrobial resistance.

3. Abscess Detection and Drainage

When a pus collection (abscess) is present, drainage is required for effective resolution, as antiseptics and antibiotics alone cannot adequately penetrate and eliminate an established abscess.

• Pressure test: Gentle digital pressure can confirm the presence of an abscess if it reveals an area of blanching (whitening) larger than expected, a sign of fluid under pressure.
• Incision and drainage: Under local anesthesia (to minimize discomfort), the physician makes a small incision to release the accumulated pus. Gentle pressure is applied to ensure as complete drainage as possible.
• Post-drainage care: Following drainage, warm soaks are resumed to maintain an open wound and facilitate continued drainage, while also helping prevent secondary infection. The wound is typically left open to drain freely rather than sutured closed.

4. Surgical Treatment

Surgical intervention, such as partial or complete nail removal, is rarely necessary but may be considered in:

• Severe, deep infections not responding to drainage
• Cases complicated by osteomyelitis or tendon sheath involvement
• Recurrent severe paronychia unresponsive to all other measures

5. Chronic Paronychia: Special Considerations

Managing chronic paronychia requires addressing the underlying predisposing factors:

• Minimize trauma and moisture exposure: Wearing protective gloves during wet work or manual labor is essential
• Antifungal therapy: Chronic paronychia is frequently caused by Candida species and other fungi, requiring antifungal agents (not antibiotics). Commonly used antifungals include:
  • Itraconazole (oral)
  • Terbinafine (oral)
  • Topical antifungal creams for milder cases
• Topical corticosteroids: In cases where inflammation and irritant dermatitis are prominent components, a topical corticosteroid (sometimes combined with an antifungal) may be prescribed to reduce inflammation
• Addressing underlying conditions: Control of diabetes, review of contributing medications, and treatment of any concurrent skin diseases are important components of chronic paronychia management

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Sources and Bibliography

• Paronychia by Anne Dulski, Christopher W. Edwards. StatPearls, NCBI Bookshelf
• DermNet NZ: Paronychia
• Rockwell PG. “Acute and chronic paronychia”. American Family Physician. 2001;63(6):1113–1116.
• Rigopoulos D, et al. “Acute and chronic paronychia”. American Journal of Clinical Dermatology. 2008;9(3):163–173.
• Mayo Clinic: Paronychia
• NHS: Nail Infections