Warts

What are warts?

Common warts

Warts are common, harmless growths of skin that occur in roughly 10 per cent of all children. They are caused by a virus called human papillomavirus (HPV). Warts are caused by the rapid growth of skin as a result of the virus. They are not cancer.

Normally, warts are found on the top layer of skin (epidermis). They may look different depending on what area of the body they are on. They can often have small black or dark red spots in the center. These spots are very small clotted blood vessels.

Some warts can cause pain and bleeding, especially the plantar type on the bottom of the feet.

Warts are most common in people between the ages of five and 20 years.

Generally, your child's doctor can diagnose a wart by looking at it. Your child will not usually need special tests.

There are three general types of skin warts

• Common warts are usually found on the fingers, toes and knees. They make up about 70 per cent of warts.
• Plantar warts are found on the pressure points on the bottom of the feet. They make up about 30 per cent of warts.
• Flat warts make up about 4 per cent of warts. They are usually smoother in appearance than common or plantar warts. They usually appear on the face, but they can be found on other body parts. They mostly affect children and young adults.

Warts can grow in size from weeks to months

Warts vary considerably in size. They are rarely larger than 10 mm (0.4 inches) from side to side.

Warts spread easily

There are more than 50 types of HPV. HPV can pass to another person from skin-to-skin contact. HPV can also be passed through contact with an object such as a towel.

Treatment of warts

Option not to treat

Viral warts will often go away on their own, but they can also persist for years. They are not dangerous. Depending on where they are located in the body, they may cause pain and discomfort, or people can be unhappy with how they look. How long it takes for warts to go away on their own varies and cannot be predicted.

Option to treat

There is no treatment to cure HPV, the cause of warts. Most treatments kill the cells that contain the virus. If treatments are started, the aim is to remove the wart without scarring.

Because some warts go away on their own, stronger treatments are often not used, except with plantar warts. Also, treatments can be painful and may not work well. People may need multiple treatments to remove the wart entirely.

There is no treatment that is considered "the best" at removing warts. Your doctor may choose different treatments depending on the age of your child, where the wart is located or what has been used so far.

Treatments to use at home

• Salicylic acid wart removal products can be purchased without a prescription at a pharmacy (there are many brands available). There are also prescription forms of salicylic acid. Apply the product once per day to the area of the wart. Usually, it is not applied to the face, genitals or normal skin unless directed by a doctor. The salicylic acid will make the wart turn into dead skin (the skin will look white).
• Duct tape or other airtight tape may be used. This can be combined with other treatments, such as applying duct tape over the salicylic acid product. The use of duct tape alone for management of warts is not very effective.
• Other medications such as podophyllotoxin, topical retinoids (such as tretinoin or tazarotene), cimetidine, imiquimod or sinecatechins might also be prescribed by your doctor.

Doctor's office treatments

• Higher concentrations of salicylic acid can be applied to the wart by your doctor.
• Liquid nitrogen, also called cryotherapy, is a common treatment for warts. The liquid nitrogen is very cold, and it freezes or burns the wart. After, the skin will likely blister and scab. When the scab comes off, the wart can come with it. This treatment is quick but can also be painful. For this reason, it is not often done in young children. Multiple treatments, or use of other treatments at the same time, are commonly necessary.
• Other treatments applied in the doctor's office include bleomycin injections, podophyllotoxin, candida injections and cantharone.

Not-so-common treatments

• Electrosurgery with a carbon dioxide (CO2) laser requires a pain medicine called a local anaesthetic.
• Photodynamic therapy involves two steps: applying a prescription cream and then exposing the wart to a specific type of light. This is used for warts resistant to other treatments.
• Surgery is very rarely used, as it may increase the chances that the virus may spread in the skin.

How can I prevent warts from happening?

• Moisturize hands and feet to prevent breaks in the skin. Tiny breaks in the skin let the virus infect the upper layer of the skin. This is why so many warts are seen on the fingers, palms and soles of the feet.
• Keep hands and feet dry.
• When in a public pool or shower, wear water shoes. The virus does very well in warm moist conditions. It is easy to pass it from person to person in pools and public showers.
• If you do have a wart on your hands or feet, keep it covered when in a public place.

How do I prevent the warts from spreading on my child or to other children?

• Discourage your child from picking the wart. They may spread the wart virus to other areas of their body.
• Avoid baths or hot tubs with other children. Warm, moist conditions make it easier to spread the virus that causes warts.
• Avoid sharing towels or sports equipment.
• If your child is picking or scratching their wart, make sure your child's fingernails are cut short, and wash their hands regularly.
• If your child has a wart on their hands or feet, keep it covered when in a public place.

When does a wart need to be seen by a doctor?

See your child's doctor if:

• warts develop on the genital area or around the anus
• plantar warts are painful or cause discomfort when walking
• warts develop on the face
• any warts are causing pain or distress

For further information about warts, see the following resource from the Society for Pediatric Dermatology: "Warts (verruca vulgaris) and what to do about them".

References

Schmitt, B. Warts. American Academy of Pediatrics, Pediatric Patient Education. Retrieved from https://patiented.solutions.aap.org/handout.aspx?gbosid=494586.

Boull, C. and Groth, D. Update: Treatment of Cutaneous Viral Warts in Children. Pediatric Dermatology (2011). 28(3), 213-217.