Paronychia is an infection of the skin fold around the nail, while a felon is an infection of the closed pad of the fingertip. Both usually follow minor trauma such as nail biting or a hangnail, and Staphylococcus aureus is the most common cause.
Key symptoms
- Red, swollen, painful skin at the side of a nail
- A pocket of pus at the nail fold
- Felon: severe throbbing pain and tense swelling of the fingertip pad
- Chronic paronychia: weeks of swelling in people with often-wet hands, with nail changes
What you find on exam
- Red, tender nail fold with or without fluctuance
- Tense, very tender fingertip pad that stops at the last finger crease (felon)
- Check for spread to the tendon sheath (Kanavel signs)
- Look for grouped blisters of herpetic whitlow, which should not be cut
Tests
- Diagnosis is clinical
- Culture of drained pus if severe, recurrent or with MRSA risk
- X-ray if a felon is long-standing or a foreign body or bone infection is possible
Treatment basics
- Early paronychia without pus: warm soaks several times a day
- Abscess: incision and drainage under a digital nerve block
- Felon: prompt drainage that avoids the center of the pad and the nerves
- Antibiotics such as cephalexin, or trimethoprim-sulfamethoxazole if MRSA risk
- Chronic paronychia: keep hands dry, wear gloves, use a topical steroid
Red flags
- Finger held bent, pain on stretching it, swelling of the whole finger (flexor tenosynovitis)
- Spreading redness up the hand or arm, or fever
- Diabetes or weak immunity with fast worsening
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; AAMC Core Entrustable Professional Activities (Core EPAs). Written by Making Synapses. Making Synapses is not affiliated with these organizations.