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Human Papillomavirus (HPV) Infection

(Abnormal Pap Test; Genital Warts; Condylomata Acuminata)


Sheldon R. Morris

, MD, MPH, University of California San Diego

Reviewed/Revised Feb 2023 | Modified Nov 2023
Topic Resources

Human papillomavirus (HPV) can be sexually transmitted and causes changes in cells, which can lead to genital warts or to precancer or cancer of the cervix, vagina, vulva, anus, or throat.

  • Different types of human papillomavirus (HPV) infect different parts of the body and can cause warts or precancer or cancer of the cervix, vagina, vulva, penis, anus, and throat.

  • Genital warts are visible skin lesions that sometimes cause burning pain; genital or anal precancer or cancer may cause bleeding or a mass or have no symptoms.

  • Doctors identify warts based on their appearance.

  • Cervical cancer is screened for with Pap tests or HPV testing, and some people at high risk are screened for anal cancer.

  • Genital warts are usually treated with freezing (cryotherapy) or medication applied to the warts.

  • Vaccines can prevent most types of HPV infection that can cause genital warts or cancer.

HPV is the most common sexually transmitted infection (STI). HPV is so common that about 80% of all sexually active people who have not been vaccinated get the virus at some point in their life. In the United States, about 14 million people become newly infected with HPV each year. Before the HPV vaccine became available, each year roughly 340,000 to 360,000 people sought care for genital warts caused by HPV. As more and more people are being vaccinated against HPV, the percentage of people with HPV infection has been decreasing.

Most infections go away within 1 to 2 years, but some persist. Persistent infection caused by some types of HPV can cause certain types of cancer.

  • Genital or anal warts: These warts are caused by certain types of HPV, especially types 6 and 11. Types 6 and 11 are unlikely to cause cancer. These warts are easily visible and are usually noticed by the person with warts or by a health care practitioner.

  • Precancer (intraepithelial neoplasia) or cancer: Other HPV types, especially types 16 and 18, infect the anogenital area (the anus and genital organs) but usually do not cause easily visible lesions. They can infect and cause changes to cells that then become precancerous or cancerous. In the anogenital area, these changes occur most commonly in the cervix, vulva, or anus, and less frequently in the urethra or on the penis. Many throat cancers are also caused by HPV. The less visible warts that can lead to precancer or cancer usually cause no symptoms. People who have a weakened immune system (immunosuppression), for example human immunodeficiency virus (HIV) infection, are at increased the risk of developing HPV-related cancer.

The types of HPV that affect the genital and rectal areas are usually spread during vaginal or anal intercourse but may also be spread through other types of sexual contact. HPV can also be spread during oral sex, causing infections of the mouth and increasing the risk of throat cancer.

Did You Know...

  • Some types of HPV can cause cancer of the cervix, vulva, anus, penis, or throat.

Symptoms of HPV Infection

In women, genital warts can occur on the vulva, vagina, and/or skin in the groin area. In men, warts usually occur on the penis, especially under the foreskin in uncircumcised men, or in the urethra. In all people, genital warts may develop in the area around and inside the anus, especially in people who engage in anal sex. Genital warts are usually caused by types of HPV that are unlikely to cause cancer.

Warts cause no symptoms in many people but cause occasional burning pain, itching, or discomfort in some.

Genital warts are easily visible and are often noticed by the person with the warts. The warts usually appear 1 to 6 months after infection with HPV, beginning as tiny, soft, moist, pink or gray growths. They grow rapidly and become rough, irregular bumps, which sometimes grow out from the skin on narrow stalks. Their rough surfaces make them look like a small cauliflower. Warts often grow in clusters.

Warts may grow more rapidly and spread more widely in pregnant women and in people who have a weakened immune system, such as those who have HIV infection.

Diagnosis of HPV Infection

  • For genital warts, a doctor's evaluation

  • For cervical cancer screening, a cervical Pap test and/or HPV testing

  • Sometimes, anal cytology (Pap test)

  • For abnormal HPV or Pap test results, sometimes colposcopy, anoscopy, and/or biopsy

Genital warts can usually be diagnosed based on their appearance. If warts look unusual, bleed, become open sores (ulcerate), or persist after treatment, a doctor should take a sample (biopsy) and examine it under a microscope to check for precancer or cancer.

For cervical cancer screening Cervical Cancer Screening and Prevention Cervical cancer develops in the cervix (the lower part of the uterus). Most cervical cancers are caused by human papillomavirus (HPV) infection. Having regular cervical cancer screening tests... read more , a Pap test and/or HPV testing is done. Doctors usually use the first HPV test to check for any one of a group of HPV types that have a high risk of causing cervical cancer. The result is positive or negative, but the HPV type is not specified. Often, doctors do a follow-up test to check for the specific HPV types that are the most likely to cause cancer (16 and 18), a process called genotyping. Genotyping is done using tests such as the polymerase chain reaction (PCR). The PCR produces many copies of a gene, which may enable doctors to identify a specific type of HPV’s unique genetic material (DNA). If a cervical Pap test or HPV testing is abnormal (positive), the doctor may do a colposcopy (use of a magnifying lens to examine the cervix) to check for cervical precancer or cancer.

In low-resource settings without access to routine Pap tests or colposcopy, screening and evaluation for cervical cancer include HPV testing and/or visual inspection with use of a type of vinegar (acetic acid) or iodine (Lugol iodine).

During colposcopy or anoscopy, a type of vinegar may be applied to the area so that warts can be seen more easily. If a lesion is seen, a biopsy is done.

Treatment of HPV Infection

  • Usually, treating lesions with topical medications or freezing (cryotherapy)

  • Sometimes, treating or removing lesions with laser, electrocautery, or surgery

If the immune system is healthy, it often eventually controls HPV and eliminates the virus. HPV infection is gone after 8 months in half of people and lasts longer than 2 years in fewer than 10%. Sometimes genital warts will go away, even without treatment. If people with genital warts have a weakened immune system, treatment is required, and the warts often return.

For genital warts, topical medications applied directly to the warts include podophyllin toxin, imiquimod, trichloroacetic acid, or sinecatechins (an ointment made from extracts of green tea). This approach requires many applications over weeks to months, may burn the surrounding skin, and is usually, but not always, effective. The warts may return after apparently successful treatment.

If topical medications are not effective, warts may be removed with a laser or an electric current (electrocautery) or by freezing (cryotherapy) or surgery. A local or general anesthetic is used, depending on the number and size of the warts to be removed.

For warts in the urethra, a viewing tube (endoscope) with surgical attachments may be the most effective way to remove them, but this procedure requires a general anesthetic. Medications, such as thiotepa inserted into the urethra or the chemotherapy drug 5-fluorouracil injected into the wart, are often effective.

Interferon-alpha injections into the wart have been found to be somewhat effective.

All sex partners should be examined for warts and other STIs and treated, if necessary. Sex partners should also have regular examinations to check for HPV infection.

Precancerous lesions of the cervix (cervical intraepithelial neoplasia, or CIN) are managed based on how severe the changes are, with either more frequent Pap tests, often with HPV testing, or a large cervical biopsy (called a cone biopsy or a loop electrocautery excision procedure, or LEEP).

Prevention of HPV Infection

  • Nine-valent: Protects against nine types of HPV

  • Quadrivalent: Protects against four types of HPV

  • Bivalent: Protects against two types of HPV

Only the nine-valent vaccine is available in the United States.

All three HPV vaccines protect against the two types of HPV (types 16 and 18) that cause about 70% of cervical cancers. The quadrivalent vaccine includes protection against the two types of HPV (types 6 and 11) that cause more than 90% of genital warts. The nine-valent vaccine adds protection against 5 other types of HPV (types 31, 33, 45, 52 and 58) that cause about 15% of cervical cancers.

These vaccines are given by injection into a muscle, usually in the upper arm. Preferably, the vaccine is given at age 11 or 12 years, but it can be started as early as 9 years. Children younger than 15 years receive two doses; people 15 years and older receive three doses.

Consistent correct use of male condoms Condoms Barrier contraceptives physically block the sperm’s access to a woman’s uterus. They include condoms, diaphragms, cervical caps, contraceptive gels, contraceptive sponges, and spermicides (foams... read more Condoms can reduce the risk of HPV infection and disorders related to HPV, such as genital warts and cervical cancer. Because HPV can be transmitted by skin-to-skin contact, condoms do not fully protect against infection.

In men, circumcision reduces the risk of getting HPV infection, as well as HIV infection and genital herpes, but not syphilis.

Other general measures can also help prevent HPV infection (and other sexually transmitted infections):

  • Decreased risk of exposure to STIs by reducing the number of sex partners, not having high-risk sex partners (people with many sex partners or who do not practice safer sex), or practicing mutual monogamy or abstinence

  • Prompt diagnosis and treatment of genital warts (to prevent spread to other people)

More Information

The following English-language resource may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

Drugs Mentioned In This Article

Generic Name Select Brand Names
Acetasol, Borofair, VoSoL
Aldara, Zyclara
No brand name available
Adrucil, Carac, Efudex, Fluoroplex, Tolak
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