Herpetic Whitlow

Overview

Herpetic whitlow is a painful infection of a finger or thumb caused by the herpes simplex virus (HSV), the same virus that causes cold sores and genital herpes. The infection produces a cluster of small, fluid-filled blisters, usually around the fingertip or nail, along with swelling, redness, and often intense pain or burning.

The virus enters through a small break in the skin, frequently after contact with an active herpes sore on oneself or another person. Although it can look alarming and is quite painful, herpetic whitlow usually heals on its own over a couple of weeks. It is important not to mistake it for a bacterial infection that needs cutting open, since draining a herpetic whitlow can worsen it and spread the virus.

Symptoms

Symptoms usually develop a few days to a couple of weeks after the virus enters the skin:

• Burning, tingling, or pain in the fingertip, often before any rash appears
• Redness and swelling of the affected finger
• A cluster of small, clear or yellowish blisters that may merge
• Throbbing pain that can be out of proportion to how the finger looks
• Sometimes fever and swollen lymph nodes near the elbow or armpit

The blisters eventually crust over and heal. The virus can stay dormant afterward and occasionally cause a milder recurrence in the same finger.

Causes

Herpetic whitlow is caused by the herpes simplex virus entering through a break in the skin of the finger. This can happen in several ways:

• Touching one's own cold sore or genital herpes sore and transferring the virus to a finger with a cut or hangnail
• Contact with another person's active herpes sore
• In healthcare or dental work, contact with infected mouth secretions without gloves (less common now that gloves are standard)
• Thumb-sucking in young children who have an oral herpes infection

Once the virus infects the skin, it can remain in the nearby nerve and occasionally reactivate, causing repeat episodes.

Risk Factors

• Having oral or genital herpes
• Frequent contact with the mouth area, such as nail biting or thumb-sucking
• Breaks in the skin, hangnails, or eczema on the fingers
• Occupations with hand contact with mouth secretions, especially without gloves
• A weakened immune system, which can make infections more severe

Diagnosis

Herpetic whitlow is usually diagnosed from its appearance and history:

• Examination: The cluster of blisters, location, and pain pattern often make the diagnosis clear, especially with a history of herpes.
• Distinguishing it: It is important to tell it apart from a bacterial fingertip infection (a paronychia or felon), since the treatment is very different.
• Laboratory tests: If the diagnosis is unclear, a swab of the blister fluid can confirm the herpes virus.

Treatment

Herpetic whitlow usually heals on its own within two to three weeks. Treatment focuses on comfort, preventing spread, and, when started early, shortening the episode:

• Antiviral medicine: Tablets such as aciclovir can help, particularly if started early or for severe or recurrent cases.
• Pain relief: Simple painkillers and keeping the finger elevated can ease discomfort.
• Protect and cover: Keep the area clean and covered with a dressing to reduce the risk of spreading the virus to others or to other parts of the body, such as the eyes.
• Do not drain it: Unlike a bacterial abscess, a herpetic whitlow should not be cut open, as this can worsen it and spread infection.

See a doctor if there are signs of an added bacterial infection, such as spreading redness, warmth, and pus.

Prevention

• Avoid touching cold sores or other herpes sores, and wash hands well if you do
• Do not pick at sores or bite nails and hangnails
• Cover an active whitlow with a dressing to avoid spreading the virus
• Healthcare workers should wear gloves when in contact with mouth secretions
• Avoid touching the eyes when you have an active herpes sore on the hand or mouth

When to See a Doctor

See a doctor if you have a painful, blistering finger infection, especially the first time, to confirm the diagnosis and discuss antiviral treatment. Seek prompt medical care if:

• The redness spreads up the finger or hand, with increasing warmth and pus (possible bacterial infection)
• You have fever and feel generally unwell
• You have a weakened immune system
• The eye becomes involved or painful, which needs urgent attention

Avoid squeezing or cutting the blisters, and avoid contact lens use until any eye involvement has been ruled out.

Related Topics

Frequently Asked Questions

References

1. MedlinePlus, U.S. National Library of Medicine. Herpetic whitlow.
2. American Academy of Dermatology. Herpes simplex.
3. Centers for Disease Control and Prevention (CDC). Genital herpes (HSV).
4. Mayo Clinic. Cold sore.