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Top tips on viral warts

Warts are a nuisance but patients want them gone – dermatology GPSI Dr Stephen Hayes outlines his management tips and pitfalls to avoid

Warts are a nuisance but patients want them gone – dermatology GPSI Dr Stephen Hayes outlines his management tips and pitfalls to avoid

1 Warts are benign epidermal growths caused by several viruses or may be seborrhoeic. Scarring does not occur unless the dermis is breached by over-aggressive treatment. They are medically trivial but socially annoying and often present to the GP. The advice that follows is generally true for all non-genital warts but particularly concerns viral warts.

2 The common viral wart affects mostly children, on the hands and feet. Warts are painless except on a weight-bearing part of the foot and rarely cause problems other than being unsightly.

3 Viral warts involute spontaneously, usually within two years. In 17 trials, placebos led to resolution of 30% of cases within 10 weeks. This tendency to self-resolve gives credence to various ‘traditional' remedies such as frogspawn, silver spoons, duct tape and so on.

4 Warts in children are best left alone. Most parents are happy with this once assured they will go in time without scarring.

5 No treatment is strikingly effective. The best trial evidence is for salicylic acid, but compliance is a problem. Stronger preparations work best, but perseverance is the key. Warts should be pared down with disposable emery boards before the treatment is applied. If a pumice stone or file is used, bear in mind it will become contaminated with wart virus.

6 Cryotherapy is hazardous. Spilled liquid nitrogen (LN2) can cause severe burns and a large spill may drive oxygen out of a room, risking asphyxiation. Others sources of cold don't freeze as hard, so are less effective. Cotton wool on a stick is less precise and risks spillage. The stick must not be dipped in the flask as it may transfer viruses that are not killed by freezing, so you need to pour the LN2 into a fresh plastic cup each time. Better to use a gun.

7 Do not freeze warts in children under 12. Older children who strongly request treatment with informed consent may have a trial. Obviously parental consent is required too. Abandon the procedure if the child pulls away. Agree on this before starting. Consent is required for all medical procedures – it need not be written but must be informed. Mention pain, blistering and the fact that cryotherapy does not always work. A leaflet is useful.

8 Cryotherapy needs to be repeated at two- to three-week intervals until success is achieved. Length of freeze depends on thickness, and may be increased at subsequent sessions if the last freeze was tolerated but did not work. Start at 10 seconds for a small wart and up to 30 seconds for a thick one. Freeze 1mm beyond the edge of the wart, control the freeze by pressing and releasing the trigger on the LN2 gun – a long continuous burst will freeze too widely. Think about underlying structures. A useful trick when freezing on the back of the hand is to pull loose skin below the wart up above the nerves, tendons and IP joints.

9 Be sure it's a wart before freezing. Cryotherapy hurts but doesn't help corns and calluses. Look in a good light with a lens – or a dermoscope – for the characteristic thrombosed capillaries of a wart, which are absent from the smooth surface of a corn. Don't freeze skin cancers either – disasters have happened.

10 Consider surgery on selected adults with warts. Filiform warts on or near the nose are very annoying and I find cryotherapy doesn't work.

A jab of local anaesthetic and three to five seconds with the hyfrecator on setting five and perhaps a light scratch with a small ring curette to remove the debris works wonders. If you burn first, then scrape, there's no bleeding. The patient won't scar unless you penetrate the dermis, but even then a 2mm flat scar is better than an ugly protruding wart, as long as this risk is explained.

I have removed hundreds of warts from patients' faces and had nothing but gratitude. The horror stories about patients suing for scarred faces arise from clumsy and inappropriate cutting and stitching, not curettage and light cautery.

Troublesome chronic plantar warts in adults may require deeper curettage and cautery. When treating such warts, I find my 2.5cm lens no-touch dermoscope helpful to see the precise limit of the wart to burn just enough but no further.

Dr Stephen Hayes is a dermatology GPSI in Southampton

Competing interests None declared

Viral warts involute spontaneously, usually within 2 years Viral warts involute spontaneously, usually within 2 years

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