Dr Phil Kieran: My son has developed warts on his back and thumb

Warts can be stubborn to remove and if you're not careful, can even spread to other parts of the body

Scratching the wart or the surrounding skin can cause it to enlarge or spread to new areas. Picture: iStock

My 12-year-old son has developed small warts on his left thumb and some tag-like warts on his back. I’ve no idea where he picked them up, but it could be connected to the swimming pool we use regularly. He’s careful to wear rubber shoes when walking around the pool area. What would you suggest?

Warts are often tricky to deal with. Also, trying to figure out where he may have picked them up is nearly impossible, as the incubation period for warts is typically between two and six months, but can be as long as 12 months.

Complicating matters further is that you can spread warts from one area of your body to another. While we do recommend wearing footwear around pools and locker rooms, this would be more of a concern if all the warts were on his feet.

Warts typically disappear over time in most people. This can happen within six months, but unfortunately, it can also take up to two years after they first appear.

Scratching or otherwise traumatising the wart or the surrounding skin can cause it to enlarge or spread to new areas.

When I was your son’s age, I had about five warts on my hands and at least three verrucae on my feet. (A verruca is just a wart that gets pushed into the skin and appears flat — this is why they usually occur on the feet.) I would have been pretty upset if someone had just told me to wait and that they would go away on their own.

Why do warts hang around for so long?

The reason warts hang around so long is that they can be good at hiding from the immune system.

Most treatments work by encouraging the immune system to recognise and attack the virus, clearing the wart.

The first line treatment I recommend is topical salicylic acid. This works by breaking down the hardened skin on the wart and encouraging a mild level of irritation. This can help shrink the wart, making it less obvious, but it can also prompt the immune system to deal with the problem. The important factor with this is applying the solution to the live wart. As you use it, a hard, dead layer of skin will build up on the top, and this should be filed back with a disposable emery board about once a week.

Cryotherapy or freezing warts is another option. This treatment involves rapidly cooling the area with liquid nitrogen, causing ice crystals to form inside the tissue, breaking open some cells and prompting the immune system to step in and clear out the problem.

It is important to understand that this treatment does not ‘freeze’ the warts off and may require multiple applications.

Cryotherapy carries risks of leaving a pale patch behind or causing blistering or scarring. Also, it hurts to get it done. For these reasons, it needs to be done by a healthcare professional.

Most of us have had warts at one stage or another, and they are usually more irritating than worrying. If your son is happy just to wait it out, you can be reassured that they are not likely to cause problems.

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