GPAtlas🧭 When to suspect
A herpetic whitlow is a painful infection of a finger or thumb (occasionally a toe) caused by the herpes simplex virus (HSV).
• HSV is the same virus that causes cold sores (HSV type 1) and genital herpes (HSV type 2).
• A whitlow usually affects the distal phalanx (fingertip), where the virus enters through a breach in the skin such as a torn cuticle.
Suspect it when a patient describes:
• A prodrome of tingling, burning or itching in the digit, followed within a day or two by painful, clustered, fluid-filled vesicles (small blisters) on a red base
• A personal or partner history of cold sores or genital herpes (common)
• Blister fluid that is typically clear rather than the frank pus of a bacterial infection
It follows a bimodal age pattern:
• Young children: autoinoculation from oral herpes, often through thumb-sucking
• Adults aged 20–30: genital herpes exposure, or occupational contact in healthcare and dental workers
It is uncommon – around 2.4 cases per 100,000 per year – which is precisely why it is so often misdiagnosed.
Distinguish it from a bacterial felon or paronychia, because the management is opposite: a herpetic whitlow is treated conservatively and must never be incised, whereas a bacterial pulp-space abscess needs drainage.
| Feature | Herpetic whitlow | Bacterial felon or paronychia |
|---|---|---|
| Cause | HSV-1 or HSV-2 | Usually Staphylococcus aureus |
| Prodrome | Tingling, burning or itch before the rash | None |
| Lesion | • Clustered clear vesicles on an erythematous base • May coalesce into bullae |
Tense erythema with a localised collection of frank pus |
| Fingertip pulp | Soft and non-tense | Tense, throbbing, often fluctuant |
| Fluid | Clear (may later turn turbid or sero-purulent) | Frank pus |
| Key action | Conservative ± oral antiviral – never incise | Incision and drainage ± antibiotic |
Source: DermNet
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