What is the appropriate management for a painful, swollen toe with a blackened toenail?

Management of Painful, Swollen Toe with Blackened Toenail

The most critical first step is to determine whether this represents a subungual hematoma from trauma, an acute bacterial paronychia requiring drainage, or a fungal infection—with immediate drainage indicated if purulent discharge is present, combined with topical povidone iodine 2% twice daily and oral antibiotics targeting Staphylococcus aureus. 1

Immediate Assessment Priorities

The blackened nail with pain and swelling suggests three primary diagnostic possibilities that require urgent differentiation:

1. Acute Bacterial Paronychia with Abscess

• Drainage is the most critical intervention if purulent discharge or fluctuance is present 1
• Bacterial paronychia typically presents with acute onset, purulent discharge, and significant pain 1
• Secondary bacterial superinfections occur in up to 25% of nail injury cases 2
• Yellow-green or black discoloration with pus suggests bacterial superinfection, which may coexist with fungal colonization 1

2. Subungual Hematoma from Trauma

• Black discoloration can result from subungual hemorrhage following acute trauma 3
• Pain occurs due to pressure from blood collection under the nail plate 3
• This requires different management than infection (typically drainage of hematoma if pressure is significant)

3. Fungal Infection (Onychomycosis) with Secondary Changes

• The nail can take on black, white, or brown-red color with fungal infection 3
• Fungal infections present with thickening, discoloration, and friable texture 4
• Pain may develop from progression of detachment or development of subungual abscess 3
• However, approximately 50% of dystrophic nails are non-fungal, so mycological confirmation is essential before starting antifungal therapy 4

Immediate Management Algorithm

Step 1: Rule Out Infection Requiring Drainage

• If purulent discharge is present: Immediate drainage combined with topical antiseptics and oral antibiotics effective against Staphylococcus aureus 1
• For severe cases with significant purulent collection, partial nail avulsion may be necessary 1
• Obtain bacterial cultures if infection is suspected 3

Step 2: Initiate Topical Antimicrobial Therapy

• Apply topical povidone iodine 2% twice daily to the affected nail bed—this has shown benefit in controlled studies for grade 1 and 2 paronychia 3, 1
• High-potency topical corticosteroids combined with topical antibiotics can be used for less severe inflammation 3, 1
• Keep the affected area dry, which is crucial for healing 1

Step 3: Oral Antibiotics if Indicated

• Initiate oral antibiotics targeting Staphylococcus aureus and gram-positive organisms if infection is present 2
• Consider sulfamethoxazole-trimethoprim for broader coverage including MRSA if initial treatment fails 2
• Oral antibiotics have shown benefit anecdotally for paronychia 3

Step 4: Supportive Measures

• Avoid repeated friction, trauma, and excessive pressure to the affected toe 3, 1
• Wear comfortable, well-fitting shoes and cotton socks 3, 1
• Implement daily antiseptic soaks with dilute vinegar (50:50 dilution) or 2% povidone-iodine for 10-15 minutes twice daily 2

Critical Diagnostic Considerations

When to Suspect Fungal Infection

• Soft, friable nail texture with thickening and discoloration strongly suggests fungal infection 4
• Toenails are more commonly affected than fingernails with fungal infections 4, 5
• Do not assume fungal infection without laboratory confirmation—collect specimens for KOH preparation and fungal culture before initiating antifungal therapy 4

Red Flags Requiring Urgent Evaluation

• Any longitudinal melanonychia (dark band) mandates exclusion of melanoma and requires urgent dermatology referral 4
• Persistent pain or drainage beyond 2-4 weeks warrants referral to hand surgery or dermatology 2
• Progressive symptoms despite appropriate treatment require reassessment and possible culture-directed therapy 1

Follow-Up Protocol

• Reassess after 2 weeks of treatment to evaluate healing 3, 1, 2
• Monitor for signs of worsening infection: increased pain, redness, swelling, or purulent drainage 2
• If infection worsens or does not improve despite drainage and antibiotics, consider culture-directed antibiotic therapy 1
• Reassessment for fungal co-infection requiring antifungal therapy may be necessary after acute infection resolves 1

Common Pitfalls to Avoid

• Never start antifungal therapy without mycological confirmation, as 50% of dystrophic nails are non-fungal 4
• Do not miss melanoma—any dark longitudinal band requires dermatology evaluation 4
• Inadequate drainage of purulent collections leads to treatment failure 1
• Failing to address occupational or lifestyle factors (moisture exposure, tight shoes) leads to recurrence 3

Preventive Measures During Healing

• Apply daily topical emollients to cuticles and periungual tissues after acute infection resolves 3, 1
• Avoid cutting nails too short and ensure proper nail trimming technique 3, 1
• Use protective measures like wearing gloves during wet work to prevent recurrence 4, 1