What Is HPV? Symptoms, Causes, Diagnosis, Treatment, and Prevention

The human papillomavirus — or HPV — is a group of more than 150 related viruses.

Each virus in the group has an associated number, which is known as its "HPV serotype."

Some HPV serotypes can cause cutaneous (skin) warts, or noncancerous papillomas, which is where the name of the virus comes from.

Skin warts are generally harmless, but they are contagious — meaning they can be passed from one person to another — and they can be aesthetically distressing to some people. Warts that grow on the bottoms of the feet, called plantar warts, can also cause pain while walking.

Other types of HPV can cause genital warts, or Condyloma acuminata — soft bumps that can grow in the anal and genital areas on both men and women.

Still other types of HPV can cause dysplasia, or precancerous changes, in the cervix, vagina, vulva, anus, penis, and oropharynx — the area at the back of the throat that includes the base of the tongue and tonsils.

Virtually everyone is infected with one or more types of HPV during their lifetime, but many will never know it because they never have any symptoms or other consequences of the infection.

Types of HPV: Skin, Mucosal, High Risk, Low Risk

HPV lives in cells found on the surface of the skin and in the moist mucous membranes that line many areas of the body.

Skin Warts

About 75 percent of HPV types cause warts on the skin, such as on the arms, face, chest, hands, and feet, according to the American Cancer Society (ACS). (1)

In healthy people, the immune system can fight off the viruses that cause skin warts, but this is often not the case in people whose immune systems are compromised — by human immunodeficiency virus (HIV), for example — suppressed by drugs to prevent organ rejection or treat autoimmune diseases, or simply less effective because of older age.

In these populations, HPV infection of the skin may not be so benign.

Mucosal, or Genital, Warts

The other HPV types — more than 40, according to the Centers for Disease Control and Prevention (CDC) — are considered mucosal types, or genital types (sometimes called anogenital types) because they typically infect the anal or genital area. Mucosal HPV types can infect the following bodily areas:

• Anus
• Inner foreskin and urethra of the penis
• Vagina, cervix, and vulva
• Inner nose, mouth, and throat
• Inner eyelids

Mucosal HPV types are categorized as either low risk or high risk.

Low-Risk Mucosal HPV

Low-risk HPV types can cause genital warts, which occur around the genitals and anus, as well as in the mouth and throat.

About 90 percent of genital warts are caused by HPV types 6 and 11, according to the CDC. (2) The HPV vaccine protects against both of these types of HPV.

High-Risk Mucosal HPV

High-risk HPV types can cause cancer. Scientists have identified about a dozen high-risk HPV types, although HPV types 16 and 18 are responsible for most HPV-related cancers.

What Are HPV 16 and 18?

HPV 16 and 18 are types of human papillomavirus that have been shown to significantly increase the risk of cervical cancer as well as genital cancers in men and women.

HPV 16 also causes the majority of cases of oropharyngeal cancer and has been linked to vocal cord cancer in people age 30 or younger, according to a study published in January 2019 in Annals of Otology, Rhinology, and Laryngology. (3)

The HPV vaccine protects against both HPV types 16 and 18, as well as several other cancer-causing types of the virus and the two main causes of genital warts.

Learn More About HPV 16 and 18

Skin warts are spread through direct skin-to-skin contact with an infected person.

You can also spread warts from one part of your body to another through touch.

Children and teens, people who bite their nails or pick at hangnails, and people with a weakened immune system have a higher risk of getting common warts.

Mucosal HPV types are transmitted through intimate skin-to-skin contact — most commonly through vaginal or anal sex but also through oral sex.

Anyone who's sexually active is at risk for getting HPV, even if you've had only one sexual partner.

You're at higher risk for genital or oral HPV if you:

• Haven't been vaccinated against HPV
• Have many sexual partners
• Have a sexual partner who has had many sexual partners
• Are younger than 25
• Started having sex when you were 16 or younger
• Are an uncircumcised man
• Are a woman who has a male sexual partner who is uncircumcised

Still, nearly all sexually active men and women get HPV at some point in their lives, the CDC notes, and it's not uncommon to be infected with more than one type of HPV at a time.

Symptoms from HPV may develop years after you become infected, so it’s often impossible to know who transmitted the virus to you.

Even with no symptoms, you can pass HPV on to other people, and you can get HPV from someone who doesn't show any symptoms.

In many cases, the immune system fights off HPV, so a person never develops symptoms and tests negative on an HPV test, if such a test is available for the body part that came into contact with the virus.

In other cases, the immune system does not prevent the virus from infecting the cells, but the infection doesn’t immediately cause symptoms. In fact, it may never cause symptoms, but the virus can be transmitted to another person through skin-to-skin or sexual contact.

And in still other cases, an HPV infection causes abnormal changes in the infected cells that can eventually develop into cancer. The time between an infection and the development of precancerous changes or cancer may be years or even decades.

The earlier HPV-related symptoms are found, the more likely they can be treated successfully.

The first HPV vaccine came on the market in 2006, and within six years of its introduction, infections with HPV types 6, 11, 16, and 18 had decreased by 64 percent among teen girls ages 14 to 19, and by 34 percent among women ages 20 to 24, according to an article published in February 2016 in the journal Pediatrics. (7)

HPV types 6 and 11 cause 90 percent of genital warts, and types 16 and 18 cause most cases of HPV-related cancer.

A subsequent systematic review and meta-analysis published in June 2019 in The Lancet confirmed the impact of HPV vaccination. (8) The meta-analysis included data on 60 million people from 14 different countries that had set up HPV vaccine programs in the previous 10 years.

U.S. Vaccination Rates

Public Health Officials Push for More Effort Vaccinating Kids Against HPV

It showed that HPV infections dropped by 83 percent among girls ages 13 to 19 and 66 percent among women aged 20 to 24. For genital warts, the drop was 67 percent among teen girls ages 15 to 19, 54 percent for women ages 20 to 24, and 31 percent for those ages 25 to 29. Precancerous cervical lesions also dropped, by 51 percent among teens ages 15 to 19 and 31 percent among women ages 20 to 24.

The study also showed that genital warts among males dropped 48 percent for those ages 15 to 19 and 32 percent for those ages 20 to 24. The researchers attributed the lower rates among teen boys and men to herd protection provided by the vaccination of young women.

At least two studies have also found that HPV vaccination lower rates of oropharyngeal HPV infections. One, published in January 2018 in the Journal of Clinical Oncology, studied young adults ages 18 to 33 in the United States from 2011 to 2014. (9) A second, published in June 2020 in The Journal of Infectious Diseases, studied men who have sex with men and transgender women age 18 to 26 in three U.S. cities during 2016 to 2018. (10)

The HPV vaccine currently used in the United States, Gardasil 9, protects against HPV types 6, 11, 16, and 18, as well as against five other types that can cause cancer: 31, 33, 45, 52, and 58.

Australian researchers have found that the HPV vaccine not only protects against genital warts and cancer, but also against childhood recurrent respiratory papillomatosis (RRP), an uncommon but incurable disease in which the virus causes wart-like growths to develop in the respiratory tract, eventually making it difficult to breathe. RRP is caused by HPV types 6 and 11, noted a study published in November 2017 in The Journal of Infectious Diseases. (11)

RRP that occurs in childhood is believed to be passed from mother to child around the time of birth. RRP can also occur in adults, usually in early adulthood, around the time HPV is commonly acquired through sexual transmission.

In the United States, the HPV vaccine is approved for preteens and adults through age 45. The CDC recommends that all adolescents get two doses of vaccine at age 11 or 12. (12)

For most people who get a first dose before their 15th birthday, only one more dose is needed, 6 to 12 months later. People who get their first dose on or after their 15th birthday need three doses total, with the second dose given one to two months after the first, and the third dose given six months after the first.

In spite of the proven protections offered by the HPV vaccine, not all Americans who could enjoy those benefits are getting them. Data released by the CDC on August 23, 2019, showed that during 2017 through 2018, coverage with one or more doses of HPV vaccine among teens ages 13 to 17 rose from about 66 percent to just over 68 percent, and the percentage of teens who had received all recommended doses of the HPV vaccine increased from about 49 percent to just over 51 percent, with the increases observed only among males. (13)

In contrast, in Australia in 2017, just over 80 percent of 15-year-old girls, and nearly 76 percent of 15-year-old boys had received three doses of the HPV vaccine, according to Cancer Australia. (14)

Learn More About the HPV Vaccine

Prostate Cancer

HPV likely has a causal role in prostate cancer. That was the conclusion of a systematic review published in July 2020, in the journal Infectious Agents and Cancer. (20)

The researchers cited numerous findings to support their conclusion but said the most important one is the reasonably consistent evidence that high-risk HPV types are significantly more prevalent in prostate cancers than in normal prostate tissues and benign prostate tissues (referring to benign prostatic hyperplasia, or an enlarged prostate). The researchers additionally noted that the mechanism by which HPV leads to cancer in the prostate is not known, but it is different from that seen in cervical cancer.

Learn More About HPV in Men

Skin Cancer

Researchers have found evidence that HPV in the skin may raise the risk of nonmelanoma forms of skin cancer when the skin is exposed to ultraviolet (UV) light. This link has long been suspected, and it was demonstrated recently by German researchers, in a study published in November 2017 in the journal PLoS Pathogens, in mouse models of HPV. (21)

Lead investigator Frank Rösl, of the German Cancer Research Center in Heidelberg, said in a press release, "These findings are an important argument in favor of also developing vaccines against cutaneous papillomaviruses."

Building on the HPV-skin cancer connection, in a study published in February 2019 in the European Journal of Clinical Microbiology and Infectious Diseases, researchers examined cancerous and noncancerous skin biopsies. They discovered HPV in 43 percent of the nonmelanoma skin cancer specimens, and almost no HPV in the noncancerous specimens. (22)

The study doesn’t prove that HPV causes skin cancer; further research is needed to fully understand the connection.

HPV can infect anyone, but different populations, including Black, Indigenous, and People of Color (BIPOC) communities, have been found to have different rates of infection in various areas of the body, as well as different rates of HPV-related cancer.

Such variability may reflect differences in prevailing community behavior, biology, or unequal access to screening tests and medical care.

The CDC reports estimates of HPV infections by race and ethnicity, based on data from the National Health and Nutrition Examination Survey (NHANES), a cross-sectional survey designed to monitor the health and nutritional status of the civilian noninstitutionalized U.S. population. (26)

The most recent estimates were published in April 2017 and reflect rates from the years 2011 to 2014 for genital HPV and the years 2013 and 2014 for oral HPV among adults ages 18 to 69. Among the findings of NHANES:

• Prevalence of any genital HPV and of high-risk genital HPV was lower among non-Hispanic Asian men and women and higher among non-Hispanic Black men and women than both non-Hispanic white and Hispanic men and women.
• Overall, prevalence of any oral HPV and of high-risk oral HPV was lowest among non-Hispanic Asian adults; any oral HPV was highest among non-Hispanic Black adults.

Using data from cancer registries, the CDC has also reported on rates of HPV-associated cancer among Americans of different races and ethnicities for the years 2012 to 2016. Among the findings: (27)

• Black and Hispanic women had higher rates of HPV-associated cervical cancer than women of other races and non-Hispanic women.
• More Black women get HPV-associated vaginal cancer than women of other races, while more white women get HPV-associated vulvar cancer than women of other races.
• Hispanic men had higher rates of HPV-associated penile cancer than non-Hispanic men.
• Rates of anal and rectal HPV-associated cancers were lower in Black women compared with white women, but higher in Black men compared with white men.
• Black and Hispanic men and women had lower rates of HPV-associated oropharyngeal cancers than white and non-Hispanic men and women.
• Overall, Asian and Pacific Islander men and women had lower rates of HPV-associated cancers than white men and women.

If you need to know more about HPV, these organizational websites can help:

American Academy of Dermatology

Get the lowdown on skin warts — their symptoms, treatment, and prevention — from the experts on skin and skin care.

American Sexual Health Association (ASHA)

Learn the basics on sexually transmitted forms of HPV, including common myths and facts and information on the connection between HPV and cervical cancer.

Centers for Disease Control and Prevention (CDC)

The CDC offers information for parents on having their children vaccinated against HPV, as well as HPV fact sheets written specifically for men and for young women.

Cleveland Clinic

Check out Cleveland Clinic’s Health Library for information on oropharyngeal cancer caused by HPV.

Mayo Clinic

Plantar warts — those that occur on the bottom of the feet —can make walking painful. The Mayo Clinic explains how to identify them and how they can be treated.

MedlinePlus

This government website links out to patient resources on warts, images, listings of ongoing research, and journal articles.

National Cancer Institute

The National Cancer Institute provides a thorough discussion of the HPV vaccine, which protects against seven types of human papillomavirus that can cause cancer, as well as two that cause most genital warts.

National Cervical Cancer Coalition

This program of the American Sexual Health Association focuses on cervical cancer information and prevention and offers an online support platform for those dealing with cervical cancer.

Office of Women’s Health

Get the information you need on genital warts, including what they are, how you get them, and what effect, if any, they could have on a pregnancy.

Planned Parenthood

For information on sexually transmitted types of HPV and for help getting tested, Planned Parenthood is the place to turn. Call 800-230-PLAN (7526).

Sex, Etc.

A website for teens, by teens, Sex, Etc. offers frank talk on sexually transmitted infections, including HPV, as well as on relationships and communicating about sex with parents and peers.

Learn More About Sexual Health Resources

Additional reporting by Ingrid Strauch.