HPV infection causes warts. More than 100 varieties of human papillomavirus (HPV) exist. Different types of HPV infection can cause warts on different parts of your body. For example, some types of HPV infection cause plantar warts on the feet, while other varieties of HPV infection are responsible for the warts that most commonly occur on the hands or face.
There are more than 40 different strains of HPV that specifically affect the genital area. Most HPV infections don't lead to cancer, but some types of genital HPV can cause cancer of the cervix — the passage between the vagina and the uterus. Vaccines can help protect against the strains of genital HPV most likely to cause genital warts or cervical cancer.
In most cases, your body's immune system defeats an HPV infection before it has a chance to create any warts. When warts do appear, they may vary in appearance depending on which variety of HPV is involved:
- Genital warts. Genital warts may appear as flat lesions, small cauliflower-like bumps or tiny stem-like protrusions. In women, genital warts appear most commonly on the vulva but may also occur near the anus, on the cervix or in the vagina. In men, genital warts may appear on the penis and scrotum or around the anus. Genital warts rarely cause discomfort or pain.
- Common warts. Common warts appear as rough, raised bumps that usually occur on the hands, fingers or around fingernails. In most cases, common warts are simply a nuisance because of their appearance, but they may also be painful or susceptible to injury or bleeding.
- Plantar warts. Plantar warts are hard, grainy growths that usually appear on the heels or balls of your feet, areas that feel the most pressure. These warts may cause discomfort or pain.
- Flat warts. Flat warts are flat-topped, slightly raised lesions darker than your regular skin color. They usually appear on your face, neck, hands, wrists, elbows or knees. HPV infections that cause flat warts usually affect children, adolescents and young adults.
Most cases of cervical cancer are caused by two specific varieties of genital HPV. These two HPV strains usually don't cause warts, so women often don't realize they've been infected. Early stages of cervical cancer typically cause no signs or symptoms. That's why it's important for women to have regular Pap tests, which can detect precancerous changes in the cervix that may lead to cancer.
When to see a doctor
If you or your child has warts of any kind that cause embarrassment, discomfort or pain, seek advice from your doctor.
HPV infection occurs when the virus enters your body through a cut, abrasion or small tear in the outer layer of your skin. The virus is transferred primarily by skin-to-skin contact.
Genital HPV infections are contracted through sexual intercourse, anal sex and other skin-to-skin contact in the genital region. Some HPV infections that result in oral or upper respiratory lesions are contracted through oral sex.
Rarely, a mother with an HPV infection may transmit the virus to her infant during delivery. This exposure may cause HPV infection in the baby's genitals or upper respiratory system.
HPV infections are common. Risk factors for HPV infection include:
- Number of sexual partners. The greater your number of sexual partners, the more likely you are to contract a genital HPV infection. Having sex with a partner who has had multiple sex partners also increases your risk.
- Age. Common warts occur most often in children and adolescents. While plantar warts may occur in adults, they're more likely to initially surface during childhood. Genital warts occur most often in adolescents and young adults.
- Weakened immune systems. People who have weakened immune systems are at greater risk of HPV infections. Immune systems can be weakened by HIV/AIDS or by immune system-suppressing drugs used after organ transplants.
- Damaged skin. Areas of skin that have been punctured or opened are more prone to develop common warts. For example, people who bite their fingernails are more likely to develop warts around their fingernails.
- Personal contact. Touching someone's warts or not wearing protection before contacting surfaces that have been exposed to HPV — such as public showers or swimming pools — may increase your risk of HPV infection.
- Oral and upper respiratory lesions. Some HPV infections may cause lesions to form on your tongue, tonsils, soft palate, or within your larynx and nose.
- Cancer. Most cases of cervical cancer are caused by two specific varieties of HPV. These two strains may also contribute to cancers of the genitals, anus, mouth and upper respiratory tract.
Preparing for your appointment
If you think you have an HPV infection, you'll probably first see your family doctor. Depending on where your warts are located, you may be referred to a doctor who specializes in disorders of the skin (dermatologist), feet (podiatrist) or reproductive organs (gynecologist or urologist).
What you can do
Before your appointment, you may want to write a list of questions to ask your doctor, including:
- What kinds of tests do I need?
- How can I prevent HPV infection in the future?
- Is there a generic alternative to the medicine you're prescribing me?
- Are there any brochures or other printed material that I can take with me? What websites do you recommend?
- Under what circumstances should I plan for a follow-up visit?
In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment.
What to expect from your doctor
Your doctor is likely to ask you a number of questions, such as:
- When did you begin experiencing symptoms?
- What are your symptoms?
- Where have you noted lesions?
- Are the lesions painful?
Tests and diagnosis
Your doctor may be able to diagnose HPV infection after visual inspection of any warts or lesions.
If genital warts aren't visible, you may need one or more of the following tests:
- Vinegar (acetic acid) solution test. Your doctor may apply a vinegar solution that turns HPV-infected genital areas white. This may help in identifying difficult-to-see flat lesions.
- Pap test. Your doctor collects a sample of cells from your cervix or vagina to send for laboratory analysis. Pap tests can reveal abnormalities that may lead to cancer.
- DNA test. This test can recognize the DNA of the high-risk varieties of HPV that have been linked to genital cancers. The test is conducted on a sample of cells taken from your cervix.
Treatments and drugs
Warts often go away without treatment. But even if your warts have disappeared or have been removed, you can still harbor HPV and may transmit the virus to others.
Medications to eliminate warts are typically applied directly to the lesion and usually take many applications before they are successful. Examples include:
- Salicylic acid. Over-the-counter treatments that contain salicylic acid work by removing layers of a wart a little bit at a time. Don't use these products for genital warts, as they will cause severe irritation.
- Imiquimod (Aldara, Zyclara). This prescription cream may enhance your immune system's ability to fight HPV. Common side effects of imiquimod include redness and swelling at the application site.
- Podofilox (Condylox). Another type of topical prescription, podofilox works by destroying genital wart tissue. Podofilox may cause pain and itching where it's applied.
- Trichloroacetic acid. This chemical treatment burns off genital warts and may cause local irritation.
Surgical and other procedures
If medications don't work, your doctor may suggest one of the following procedures, which physically remove warts by:
- Freezing with liquid nitrogen (cryotherapy)
- Electrocautery, which uses an electrical current to burn off warts or lesions
- Surgical removal
- Laser surgery
It's difficult to prevent HPV infections that cause common warts. If you have a common wart, you can prevent the spread of the infection and formation of new warts by not picking at a wart and not biting your nails.
You may reduce the risk of contracting HPV infections that cause plantar warts by keeping your feet clean and dry, wearing clean socks, and wearing shoes or sandals in public pools and locker rooms.
You can reduce your risk of developing genital warts and other HPV-related genital lesions by:
- Being in a mutually monogamous sexual relationship
- Reducing your number of sex partners
- Using a latex condom, which may prevent some but not all HPV transmission
A vaccine known as Gardasil protects against the strains of HPV that cause most genital warts. Gardasil also protects against the HPV strains most likely to cause cervical cancer. Another vaccine, called Cervarix, protects against cervical cancer but not genital warts.
The national Advisory Committee on Immunization Practices recommends routine HPV vaccination for girls and boys ages 11 and 12. If not fully vaccinated at ages 11 and 12, they recommend that girls and women through age 26 and boys and men through age 21 receive the vaccine. However, men may receive the HPV vaccine through age 26 if desired. These vaccines are most effective if given before becoming sexually active.