Warts are caused by viruses, specifically HPV (human papillomavirus).
The virus causes keratin, which is a hard protein on the top layer of the skin, to grow too fast.
Warts are not the same as moles. Moles are typically dark while warts are often the same color as the person's skin.
The appearance of a wart can vary depending where it is on the body and how thick the skin is. A wart that is located on the sole of the foot is known as a verruca.
Contents of this article:
Fast facts on warts
Here are some key points about warts. More detail and supporting information is in the main article.
- A wart is a small growth on a person's hands or feet. It looks like a solid blister or a small cauliflower.
- There are several types of wart including common warts, verrucas, plane warts, filiform warts, and mosaic warts.
- Most warts disappear on their own and do not need to be medically treated.
- Treatments for warts include salicylic acid, duct tape, cryotherapy, surgery, laser treatment, electrocautery, photodynamic therapy, chemical treatments, cantharidin, and antigen shots.
- Warts or verrucas should be covered up with a waterproof Band Aid when swimming.
What causes warts?
Warts are caused by a virus.
Different HPV strains cause warts. The wart-causing virus can be passed on by close skin-to-skin contact, as well as through contact with towels or shoes.
The wart-causing virus can be spread to other parts of the body in the following ways:
- scratching or biting a wart
- sucking fingers
- biting fingernails can cause warts to spread on the fingertips and around nails
- shaving (face or legs)
A person whose skin is damaged, wet, or comes into contact with rough surfaces is more likely to catch the infection. For example, a person with scratches or cuts on the soles of their feet is more likely to develop a verruca in and around public swimming pools.
As everyone's immune system is different, some people may develop warts when they come into contact with HPV, while others won't. The risk of catching warts from another person is fairly small, but it exists. Genital warts are much more contagious.
Most warts are harmless, however, a few strains of HPV can cause warts that appear on, in, or around the genitals. These warts are more serious and, in women, can potentially lead to cervical cancer.
Anyone who develops genital warts should see their doctor for assessment.
Treatment for warts
The majority of warts clear up without any treatment. How long it takes for them to clear up varies considerably from person to person. They tend to clear up faster among young children. Some warts may take several years to clear up. Less commonly, warts may clear up without treatment within weeks.
Some treatments can cause the skin around the wart to become irritated; others may cause pain, and even blistering. The type of treatment depends on where the wart is located and how many of them there are.
There are many treatments for warts, because there is no one perfect treatment. All treatments are designed to irritate the skin, and get the body's own infection-fighting cells to clear the warts.
Most over-the-counter creams, gels, paints, and medicated Band-Aids that are available from a pharmacy contain salicylic acid. It is important to protect the skin before applying this treatment because salicylic acid may destroy healthy skin. Petroleum jelly or a corn plaster can be used to protect the skin around the wart.
Before applying the medication, soak the wart in water for about 5 minutes. Rub dead tissue off the surface of the wart each week using a pumice stone or emery board (make sure not to share this with anybody else).
In most cases, treatment is applied daily for about 3 months. If the skin becomes sore, stop the treatment.
Medications containing salicylic acid should not be used on the face. People with poor circulation should not use medications that include salicylic acid without checking with their doctor.
Some people use duct tape to get rid of warts. It should never be used for warts on the face.
Duct tape is placed over the wart and left there for about 6 days. The wart is then soaked in warm water for about 5 minutes, after which the dead tissue is gently rubbed off using an emery board or pumice stone. It is important that the emery board or pumice stone is not used by anybody else.
The wart is then left uncovered overnight, and a new piece of duct tape is placed on it the next day.
Very cold liquid, often nitrogen, is sprayed onto the wart, freezing it and destroying the cells. A blister develops, which eventually turns into a scab and falls off a week or so later.
This treatment must be carried out by a healthcare professional and may require a local anesthetic. If the wart is large, several treatments may be required over a number of weeks. Cryotherapy has a lower risk of skin irritation compared with medications containing salicylic acid or the use of duct tape.
Pharmacies sell dimethyl-ether/propane spray, which people can self-administer, although it should not be used on the face. This treatment is not as effective as in-office cryotherapy.
In some cases, surgical removal may be required.
This is less common for warts. Surgery also carries a higher risk of scarring. If the warts resolve by themselves, they will not scar. However, sometimes a doctor may recommend surgery, for instance, if other treatments have not worked.
The surgery might be conducted under local or general anesthetic. If the wart is very big, it will be cut out. Smaller warts may be scraped off using a curette (a surgical scraping instrument). Doctors may recommend that people apply a topical cream to the site even after the wart has been removed, to increase likelihood of clearance.
A precise laser beam is used to destroy the wart. Laser treatment is usually recommended for warts that are hard to treat.
These are available on prescription. They may include diphencyprone, trichloracetic acid, and podophyllin. They must be applied only on the wart and not on the surrounding skin.
This substance is extracted from an insect called a blister beetle. The doctor will apply it on the warts. Usually, this extract is mixed with other chemicals, applied onto the skin, and covered with a bandage.
It is painless; however, the resulting blister may be uncomfortable. The blister lifts the wart off the skin so that the doctor can them remove the dead part of the wart.
Candida Antigen shots
The human body's immune system does not realize that a wart is there. However, if the immune system is stimulated locally, some activated immune cells in the area will recognize the wart and take care of it. The advantage of using antigen shots is that it leaves no scarring.
Doctors may sometimes treat pregnant women, or they may decide to wait until after the pregnancy is over.
If warts have not responded to standard treatments, a doctor may refer the patient to a dermatologist (skin specialist). The dermatologist may use some of the following treatments:
- Immunotherapy - the aim here is to get the patient's immune system to destroy the warts.
- Bleomycin (Blenoxane) - this is injected into the wart and kills the virus. Bleomycin is also used for treating some types of cancer.
- Retinoids - these disrupt the wart's skin cell growth. Retinoids are derived from vitamin A.
Antibiotics are not effective for treating warts. Antibiotics are used for bacterial infection, not viral infections. Warts are caused by HPV, which is a virus.
Common warts may be difficult to eliminate completely or permanently, especially those located around and under the fingernails and toenails. Many people who are susceptible to warts will regularly have them, even after successful treatment.
Experts say that sometimes more than one treatment approach is needed for better management of warts. It often takes combined in-office and home treatments to effectively clear warts.
Types of wart
There are several types of wart, below are some of the most common:
Common warts (verruca vulgaris)
- Common warts have a rough surface.
- They are firm and raised and may have a cauliflower-like appearance.
- Common warts can appear in any part of the body, but are more common on the knuckles, fingers, elbows, and knees or areas around broken skin.
- Often they have tiny dark spots, which are from blood vessels that have clotted, called "seed" warts.
- Verrucas appear on the soles of the feet, sometimes the heel and toes.
- They usually grow back into the skin because the weight of the person pushes onto the sole of the foot.
- They can be painful.
- It is common for verrucas to have a black dot in the middle, with a surrounding hard, white area.
Plane warts (verruca plana)
- Plane warts are round, flat, and smooth.
- They are generally yellowish, brownish, or skin color.
- They are also known as flat warts and are more common among young children.
- Most commonly, children get them on their face, men get them in the beard area, and women get them on their legs.
- They tend to grow in larger numbers, often 20-100.
Filiform warts (verruca filiformis)
- Fiiliform warts are long and thin in shape, like threads.
- They usually develop on the eyelids, neck, and armpits.
- They can grow quickly.
- Mosaic warts, or "seed" warts grow in clusters; sometimes they number in the hundreds.
- They are not generally painful.
- They are often resistant to treatment.
When to see a doctor
If a person thinks they have a wart, they should tell their doctor the next time they see them. Most warts do not need to be treated medically. Most warts disappear naturally. If an individual is not sure and wonders whether it may be something else, they should go and see their doctor to have it checked.
See a doctor if the wart:
- causes pain
- bleeds easily
- changes appearance
- spreads easily to other parts of the body
- comes back
Individuals who want the wart removed for cosmetic reasons should see their doctor. Podiatrists (foot specialists) can give advice about verrucas.
Diagnosing warts and verrucas
Warts and verrucas are easy for doctors to identify simply by examining them. The doctor may ask whether any other family members have warts. Occasionally, they may take some tissue from a wart and examine it under a microscope.
Complications that some people may experience include:
- people who have many warts, especially on their face, may find their self-confidence is affected
- some treatments may cause pain and irritate the skin around the wart
- scarring is possible, although it is unusual
- it is harder to successfully treat warts if the patient has a weakened immune system
- people with weakened immune systems are at a higher risk of their warts becoming malignant, although this is rare
Prevention of warts
Ways to reduce the risk of developing warts:
- do not touch other people's warts
- do not use towels, flannels, or other personal items of people who have warts
- do not share shoes and socks with a person who has verrucas
- do not scratch warts or verrucas, this can cause them to spread
- wear sandals when going into and out of communal showers
- wear sandals when walking around communal pools
- cover warts or verrucas with a waterproof Band-Aid when swimming
- wear socks
- wear gloves in the gym if warts are on the hands
- do not brush, comb, shave, or clip hair in areas that have warts
- when filing or cutting nails do not use the same utensil on the infected nail and the healthy nails
- do not bite fingernails if warts are near them
- keep hands as dry as possible
- wash hands thoroughly after touching a wart