What are warts and how are they treated?

Around one in 10 people in the UK have warts, which are harmless growths that can appear anywhere on your body, including on your genitals or in your mouth.

Most commonly, a wart sits on your skin, is firm, prominent and contains keratin — the same hard protein found in your hair and nails. However, warts can also be flat — these warts usually occur on the soles of your feet.

Warts have tiny black dots inside them, which are blood clots in blood vessels (thrombosed blood vessels).

What causes warts?

Warts are caused by infection with human papillomavirus virus (HPV). 

The virus causes too much keratin to build up in the top layer of your skin (epidermis), which results in a wart forming. 

Risk factors for warts

As warts are caused by infection with a virus, you’re more likely to develop them if your immune system is suppressed, either by a health condition (eg HIV, certain types of cancer) or treatment for a health condition (eg steroids, chemotherapy). 

Your risk of developing warts is also higher if you engage in skin-to-skin contact with anyone who has warts or come into contact with shedded skin from warts, which can happen in public places (eg when walking around barefoot in a public swimming pool) or when sharing towels or clothes with someone who has warts. 

Wart symptoms

In most cases, warts don’t cause any symptoms. However, if you develop a wart on an area of your body that is exposed to lots of friction, you may experience some pain eg if you have a wart on your foot and wear tight shoes. 

When to see a doctor

If you’re certain that you have developed a viral wart, you don’t need to see a doctor. You can purchase over-the-counter wart removal treatments from your local pharmacy.

If you’re not certain what has caused your suspected wart or have multiple, widespread warts, see your GP. The widespread appearance of warts may be a sign that there is a problem with your immune system due to an underlying, undiagnosed health condition. This does not apply to a few viral warts sitting in a cluster in one area, as viral warts can spread locally even in healthy individuals.

Diagnosing warts

Warts are usually diagnosed through examining them by sight . However, if it isn’t clear on sight whether your wart is caused by a virus or if the growth is cancerous, your doctor may remove it and send it to the laboratory for investigation under a microscope. 

Laboratory testing is more likely to be performed if you’re taking immunosuppressants eg if you have had an organ transplant. This is because you’re at greater risk of developing a type of cancer called squamous cell carcinoma, which can look similar to viral warts. 

Medical treatments for warts

In most cases, if you have a healthy immune system, warts will disappear on their own after one to two years. You can use an over-the-counter wart removal treatment containing salicylic acid to speed up the disappearance of your warts — this should not be used on your face, neck or genital area. Treatments are usually in the form of a patch, pad, ointment or liquid that contains salicylic acid, which causes the skin it is used on to peel off. 

Although most viral warts disappear on their own, those on the soles of the feet tend not to go away without treatment. 

If you have a wart that you want removed, you can talk to a doctor specialising in skin conditions (a dermatologist) about your treatment options. 

Warts can be surgically removed by a scraping or shave procedure, burned off from the base with electrosurgery or frozen off with liquid nitrogen (cryotherapy). 

Warts that don’t respond to simple treatment methods (recalcitrant warts) can be treated with diphencyprone. This chemical is painted onto your wart to stimulate an immune reaction from your body. You will need multiple treatments, which over time cause the wart to resolve. Diphencyprone treatment is not suitable if you’re pregnant or breastfeeding, and needs to be performed or supervised by a dermatologist. 

Other treatments for recalcitrant warts performed by dermatologists are injections with bleomycin (a chemotherapy drug) and laser treatment.

It is important to note that removal of your wart doesn’t prevent it from recurring as the virus remains in your body. 

Are there any health risks of warts?

Warts present on your skin don’t usually pose any risk to your health. However, warts present in your mouth (oropharyngeal) or genital area (ie warts that develop on the mucous linings of your body) do carry a risk of becoming cancerous. 

If you’re concerned about a wart, particularly if it is on your genitals or in your mouth, see your GP for advice. 

How to reduce your risk of viral warts

To avoid infection with HPV, which causes viral warts, don’t share towels or footwear, and don’t walk barefoot in public places, such as swimming pools and gyms. At the gym, make sure you sanitise the gym equipment before you use it. 

Also, avoid direct contact with warts and practise good daily hygiene, changing your socks regularly and avoiding transferring anything from your shoes and socks onto your skin.