Warts are noncancerous skin growths caused by infection with the human papillomavirus (HPV). Many different types of HPV exist that can cause warts to form on the skin or mucous membranes (e.g., mouth, genitals). Warts are usually pink to flesh-colored and have a rough texture, but some have a dark color and a smooth feel.
The major categories of warts include:
- Common warts. Typically appear on the fingers, especially in areas where skin has been broken around the nails and on the back of the hand.
- Foot warts. Also known as plantar warts, they appear on the soles of the feet at pressure points (such as the balls and heels of the feet).
- Flat warts. Small, smooth warts that typically grow in large groups of between 20 and 100 warts at a time, most commonly on the face of children and in areas irritated by shaving in adults.
- Genital warts. Irregular, bumpy growths with the texture of a small cauliflower that are transmitted through sexual contact. They may appear near the genitals and other body areas, and are usually relatively harmless. However, some types may cause abnormalities that can lead to genital cancer.
Warts are contagious, but most only pose a very low risk of being passed to another person through direct or indirect contact. However, genital warts are considerably more contagious than most other types of warts. Most warts pose no significant health risks and will disappear within a year or two of first appearing. However, because warts can be unsightly – and in the case of genital warts, may pose significant health risks – some patients may choose to treat them with medications or chemicals, or to have them surgically removed. However, it is not uncommon for warts to recur even after they've been treated effectively.
Warts are noncancerous skin growths caused by the human papillomavirus (HPV). Types of this virus cause an infection that shows up in the top layer of skin, inside the mouth, on the genitals or in the rectal area. In most cases, warts are pink to flesh–colored and have a rough texture. However, they also can have a dark color and a smooth feel.
There are several different major categories of warts. The type of HPV a person contracts will determine the type of wart that develops. More than 100 HPV viruses have been identified. These viruses stimulate the rapid growth of cells on the outer layer of the skin (epidermis), causing the formation of warts on the skin and mucous membranes.
Warts can develop at any age, but are most common in children. Some people appear to be more susceptible to warts than others. Individuals who develop certain types of warts should have them treated as soon as possible. Left untreated, long standing warts can deposit the virus into surrounding skin. This can lead to development of new warts, even after the original wart has been removed.
Types and differences of warts
There are several different types of warts. They include:
- Common warts. Typically appear on a patient's fingers, especially in areas where skin has been broken around the nails (such as where fingernails are bitten or hangnails are picked) and on the back of the hand. They also may appear on the knees or the face. Common warts are round or irregularly shaped and less than a half-inch (1 centimeter) across. Colors include gray, yellow or brown. They sometimes are called &seed warts,& because blood vessels connected to the wart cause black dots that resemble seeds.
- Foot warts. Also known as plantar warts, they appear on the soles on the feet at pressure points (such as the balls and heels of the feet) and may grow in clusters known as mosaic warts. They often resemble corns or calluses, but have a blood supply and will bleed if cut or removed. The pressure of walking often flattens foot warts and forces them back into the skin, while the surrounding skin thickens. These warts may be painful and feel like a stone in the shoe. In some cases, they may grow on top of the foot or toes, where they are usually raised and more fleshy. Like common warts, foot warts also have tiny black dots resulting from blood vessels.
- Flat warts. Small, smooth warts that typically grow in large groups of between 20 and 100 warts at a time. Flat warts are smooth and yellow-brown, pink or flesh-colored. Although they can appear anywhere, they are most common on the face of children and in areas irritated by shaving in adults. This includes the beard area of men and the legs of women.
- Genital warts. Also known as venereal warts, there are more than 30 varieties of these viruses. Most sexually active people have been exposed to a form of the human papillomavirus (HPV) that causes genital warts at some point. However, symptoms do not develop in the majority of cases, according to the National Women's Health Resource Center. They tend to manifest as irregular, bumpy growths on the genitals or anus with the texture of a small cauliflower that appear between one month and six months after infection. Low-risk types cause warts in some people. High-risk types may cause warts, and may cause abnormalities that promote cancer of the cervix, external genitalia and anus.
Potential causes of warts
Warts are caused by infection with the human papillomavirus (HPV), usually through a cut or other break in the skin. Warts are passed from person to person either by direct or indirect contact (such as through sharing a towel or other object). Despite this, the risk of catching common, foot or flat warts from another person is relatively small. Factors that increase the risk of contracting warts include:
- Having damaged or cut skin
- Having a weakened immune system
- Multiple exposures to HPV
Genital warts are more contagious than other types of warts and are usually transmitted through sexual contact. People most at risk include those who engage in frequent sexual activity with multiple partners, especially without using a condom. HPV that is sexually transmitted can remain in the person's system without the appearance of warts. Nonetheless, a person infected with the HPV virus that causes genital warts can pass the virus to others even if warts are not present. It is unknown when a person with genital HPV can transmit the virus and for how long transmission is possible.Infection with HPV is more likely in skin that has been damaged in some way. Some people are more likely to catch the virus than others, with certain populations – such as people with weakened immune systems – at greater risk than others. In most cases, several months will pass before an infection with HPV will result in a visible wart.
Signs and symptoms of warts
The most prominent symptom associated with human papillomavirus (HPV) infection is the presence of the wart itself. In some cases – such as warts that grow inside a woman's cervix – these warts may be too small or hidden to be easily seen.
Most warts are painless unless they are bumped or otherwise irritated, which may result in bleeding of the wart or pain. However, plantar warts can be extremely painful when pressure is placed on them through walking. Also, genital warts may itch, burn or bleed, and may interfere with sexual intimacy, bowel movements and urination.
While most warts do not pose significant health risks, there are exceptions. For example, genital warts have been linked to abnormalities that may lead to cervical cancer in women, cancer of the penis in men and anal cancer in both sexes.
A physician should be consulted if any of the following occur in relation to a wart:
- Color changes
Diagnosis and treatment methods for warts
A physician will perform a complete physical examination and compile a thorough medical history. In most cases, warts can be diagnosed based on their appearance. In some cases, a growth may need to be removed and examined under a microscope before a definitive diagnosis can be made.
In children, warts often disappear on their own without the need for treatment. The process many take several months to years. In adults, warts frequently do not disappear as quickly or easily, but also will eventually disappear on their own.
However, some warts require medical treatment. Over-the-counter remedies are available, but many contain chemicals such as acid that can be dangerous if not used correctly. For this reason, they should only be used after consultation with a physician. For more persistent cases, prescription medicines and surgical techniques are available to treat warts.
In all age groups, warts that are painful or otherwise bothersome, or that rapidly multiply, should be treated. A variety of treatments are available, depending on the type of wart. They include:
- Common warts. An over-the-counter topical salicylic acid gel or plaster may be used to effectively treat warts. Treatment is usually daily for several weeks, and it may take a long period of time before the wart begins to disappear. Treatment should be stopped if the wart becomes sore. A dermatologist can also treat a child's common wart by applying cantharidin to the wart. Cantharidin is a chemical extracted from a beetle mixed with other substances and painted onto the wart. This causes a blister to form under the wart within a few hours. After about one week, the dermatologist clips away the wart from the top part of the blister.
Cryotherapy is normally recommended to treat stubborn warts in adults and older children. In this procedure, the wart is frozen with liquid nitrogen and removed by a dermatologist. Although it may be uncomfortable, cryotherapy does not usually result in scarring. In most cases, the procedure will need to be repeated at one- to three-week intervals. Therapy in the form of electrosurgery (heated electric wire applied to destroy the wart) can also be used to treat warts in adults and older children.
- Flat warts. Because these warts tend to form in large clusters, skin peeling methods are often the best way to treat them. This can be accomplished through daily applications of salicylic acid, topical retinoids, glycolic acid or other surface peeling preparations.
- Foot warts. These warts can be difficult to treat because much of the wart remains below the skin surface. Salicylic acid plasters and other chemicals can be applied to the wart, or various surgical techniques may be used. These include laser surgery, electrosurgery or an incision to remove the wart. A change in footwear may be recommended to reduce pressure on the wart, and techniques may be suggested for keeping the foot dry so that moisture does not allow warts to spread.
- Genital warts. These warts should always be treated by a physician, and never with over-the-counter solutions used to treat other warts. A dermatologist may treat genital warts with acid applications (bichloracetic acid or trichloroacetic acid) or prescription medicines such as podofilox gel. Genital warts can also be surgically removed, which reduces the risk that the virus will be passed on to others. Surgical techniques include excision electrosurgery, cryotherapy and laser surgery. Genital warts may require more than one treatment, as the virus may remain deep in the layers of the skin.
In some cases, a dermatologist may treat a wart by injecting it with the anti-cancer drug bleomycin, which kills the HPV virus. Though effective, this technique can also be painful and cause side effects. Immunotherapy also is sometimes used to treat warts. This technique attempts to use the body's own immune system to kill the wart. One form of immunotherapy involves injecting the wart with interferon, a drug that boosts the body's immune-system response. Imiquimod cream is a prescription medication that boosts the immune-system reaction to a wart. Initially intended to treat genital warts, it is now prescribed to treat other warts as well.
Prevention methods for warts
People can take several steps to reduce the risk of contracting most types of warts. These steps include:
- Do not bite fingernails that have warts near them.
- Do not brush, clip, comb or shave areas of the body that have warts. This helps prevent the spread of the virus.
- Do not pick warts, as this may spread the virus. Cover the wart with a bandage if necessary to prevent the virus from spreading.
- Do not use nail clippers or nail files on warts if you also intend to use them on fingernails.
- Do not walk barefoot in public places. Human papillomavirus (HPV) that causes foot warts thrives in warm, moist environments such as shower floors, locker rooms and public swimming areas.
- Keep hands dry, as warts thrive in areas of moisture.
- Wash hands carefully after touching warts.
The risk of genital warts can be reduced in several ways. Depending on the nature and location of the warts, using a condom can significantly reduce – but not eliminate – the risk of contracting the HPV virus. However, refraining from sexual activity is the only sure way to avoid genital warts or other sexually transmitted infections.
Ongoing research regarding warts
Several years ago, a well-publicized study indicated that patients could have great success treating warts by using duct tape. According to the study, patients covered warts in duct tape for six days, then soaked the warts in water before rubbing them with an emery board or pumice stone. Repeated applications of this procedure cause the warts to vanish.
Scientists believe the duct tape may irritate the wart and surrounding skin, prompting the immune system to react and attack the wart. Patients should consult with their physician before trying this &duct-tape therapy& on their warts.
Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions related to warts:
- What type of wart do I have?
- What may have caused my warts to form?
- Are warts dangerous to my health?
- Can I spread my warts to other people?
- Are my warts likely to spread to other parts of my body?
- Do my warts require medical treatment? If so, what are my options?
- Is it likely that I will develop warts again in the future?
- How can I prevent warts from forming or reforming?
- When will my warts disappear?
- Will my warts leave scarring after they heal?