Skin problems health centre

Freezing beats other treatments for warts – but not verrucas

BMJ Group News

Having a wart frozen with liquid nitrogen is the best way of getting rid of it, researchers say. Almost half of people got rid of their warts after 13 weeks’ liquid nitrogen treatment. Verrucas are more stubborn though, and any treatment is less likely to be successful.

What do we know already?

Warts are growths on your skin caused by a virus. They have a bumpy, cauliflower-like appearance. Warts that affect the feet, usually called verrucas, tend to appear as rough patches of skin, often with several black dots. These dots are tiny, broken blood vessels.

Warts don’t usually cause any serious problems, but they’re contagious and can be painful. Popular ways of getting rid of them include having them frozen by a doctor, using over-the-counter treatments like salicylic acid (sold as Bazuka gel and Verrugon, among other brands), and home remedies like covering a wart with duct tape. Having a wart surgically removed is a more drastic option that usually leaves a scar - and there’s no guarantee that the wart won’t come back afterwards.

A new study has looked at two of the most popular treatments - freezing and salicylic acid - to see how they compare with a wait-and-see approach.

What does the new study say?

For most warts, freezing worked best. People had their wart frozen every two weeks, and 49 percent of people were cured after 13 weeks. Salicylic acid got rid of warts for just 15 percent of people. It also involved more fuss, with a daily routine of filing down the wart, protecting the surrounding skin with tape and applying the gel. Among people who had no treatment, only 8 percent found their wart had gone after 13 weeks.

Verrucas were harder to treat in many cases, probably because of the layer of hard skin that covers them. Freezing and salicylic acid both had a 50 percent success rate for children aged under 12, but only helped about 5 percent of people aged 12 and over. Verrucas often went away by themselves for children, but not for teenagers and adults.

Both warts and verrucas were harder to treat if people had had them for six months or more.

Freezing caused the most side effects, such as pain and blistering. Despite this, people who had their warts frozen tended to be happiest with their treatment. Salicylic acid caused skin irritation for some people.

How reliable is the research?

The study looked at 250 people who were randomly split between the freezing, salicylic acid and wait-and-see groups.

Usually in medical trials, to prevent bias, the treatment people are allocated is kept hidden until the end. That's easy enough when testing a drug against an identical-looking placebo pill, but in this trial, patients all saw the treatment they were getting. The researchers also knew who'd been given which treatment. This makes the trial less reliable. For exampe, if one of the researchers believed a particular treatment to be the best, he or she might be more likely to give that treatment the benefit of the doubt when checking if a wart had disappeared.

The new study conflicts with two previous trials, which found that freezing was no better than salicylic acid.