Human Papillomavirus (HPV)


What is Human Papillomavirus?

Human Papillomavirus (HPV) is a group of viruses that is made up of over 150 strains, also called HPV “types”. More than 40 types of HPV are transmitted sexually and can infect the genitals as well as the mouth and throat of both males and females. HPV infection is currently the most common sexually transmitted infection (STI) in the United States, and occurs most often in people during their late teens to early 20s. The Center for Disease Control (CDC) estimates that one in four people in America are currently infected with HPV and nearly all sexually active individuals will contract an HPV infection at some time in their lives. Most people may not even know that they have contracted HPV and will unknowingly pass it on to their partners during sexual activity.1


Two individuals' feet interlocked and peeping out of white bed sheets.

According to the Center for Disease Control (CDC), about 14 million American people are newly infected with Human Papillomavirus (HPV) every year. Transmission of HPV can occur via skin-to-skin contact with an infected person. HPV is most commonly transmitted during vaginal, anal, or oral sex. Other types of sexual skin-to-skin contact (as in foreplay or manual stimulation) and sharing sex toys with an infected person can also lead to the spread of HPV. Although rare, it is possible for a mother to pass HPV to an infant during childbirth. It is not common for kissing to lead to transmission, but oral HPV infections can occur as a result of oral sex. The virus can be contracted even if the infected person does not have any symptoms (such as genital warts). Anyone who is sexually active is at risk for contracting HPV, regardless of the individual’s number of sexual partners.1 In fact, the most common time for males and females to become initially infected with HPV is right after they first become sexually active.2


In many cases, HPV does not cause any noticeable symptoms, and it may take months or even years after the initial infection for symptoms of HPV to appear. Most often the body’s immune system is able to fight off the infection on its own, and the virus goes away within about two years without ever causing any problems for the infected individual. This is why many people who are currently infected with one or more strains of the virus have no idea that they have contracted it. When they do occur, symptoms of HPV manifest in the form of cell overgrowth; an infected person can develop benign warts or even cancer.1 HPV does not cause infertility in either males or females. However, if the symptoms of HPV are left untreated for long periods of time, it may become necessary to treat them with medical procedures that can leave males and females infertile.2

Genital Warts

HPV causes almost all warts on the human body, but different strains of HPV are specialized to cause warts in different areas. Genital and anal warts are most frequently caused by HPV types 6 and 11. Most warts are, in fact, types of benign tumors that develop when the HPV enters a cell and causes cell division. Anogenital warts generally do not cause any health problems, but are highly infectious and oftentimes considered unsightly or painful.

Warts may vary in appearance from large cauliflower-like growths to small pink bumps that can be difficult to see. They may be raised or flat and may grow and spread rapidly. Typically the warts are not painful, although, in some cases they may cause pain, bleeding, and itching. For females, genital warts can develop on the inner and outer labia, the lower area of the vagina, on the cervix, and/or around the anus. For males, warts may appear on the shaft or on the tip of the penis, on the scrotum, and/or around the anus. Genital warts can also develop in the mouth or the throat of a person who has performed oral sex on an infected person. The CDC reports that about 360,000 people infected with HPV experience warts as a symptom per year. Genital warts can be treated or removed by a doctor. If left untreated, the warts may grow, stay the same, or go away in time.1


Some types of HPV can cause cell overgrowth that leads to cancer of the vulva, vagina, anus, penis, throat or tonsils. There are at least 13 known strains of cancer-causing HPV, all of which are different from the strains that cause warts.2 The most common HPV-related cancer is cervical cancer, which is a major concern for females as there are about 11,000 new cases of cervical cancer per year.1 HPV types 16 and 18 are the most common types that cause cancer of the genitals, and are responsible for nearly three quarters of cervical cancer cases.2 Strains like HPV 16 and 18 first cause precancerous lesions in the genital region, which may develop into cancer later in life.

HPV causes cancer more often in females (about 17,600 cases per year) then in males (about 9,300 cases per year). Once precancerous lesions are present, it can take many years before cancer develops, and in some lucky cases cancer may not develop at all. Symptoms of cancer include pelvic pain, vaginal bleeding, fatigue, weight loss, and genital discomfort. These symptoms usually do not occur until cancer has progressed into advanced stages.2 There is no way to know for sure if cancer will develop from a cancer-causing strain of HPV in a given patient, but it is known that people with weak or compromised immune systems (such as those with HIV/AIDS) are likely to develop cancer faster than someone with a healthy immune system.1


For Genital Warts

People with visible warts or who suspect that they may have been infected should be examined by a doctor and treated as necessary. Application of a mild acetic acid solution (similar to vinegar) highlights any existing warts that are less visible to the naked eye, allowing physicians to further diagnose HPV. A doctor may also perform a complete pelvic exam and Pap smear (for females) as well as an examination of the rectum.

Unfortunately, there is currently no treatment that can completely eliminate HPV. Doctors can, however, remove warts by freezing them off with liquid nitrogen (cryotherapy), applying trichloracetic, burning them with electro-cautery, or destroying them with lasers. Prescriptions are available in some cases for at-home treatment. These include Podofilox and imiquimod creams. Surgery may be necessary to remove warts that are too large or difficult to treat with the other methods. Patients should revisit their doctor if their warts return after treatment.

For Precancerous HPV

Because of the asymptomatic nature of precancerous HPV, it is critical for females to get routine Pap smears to test for cervical abnormalities. Pap smears are generally administered annually to females after having sex for the first time or when they reach 21 years of age, whichever comes first. To administer a pap smear, a gynecologist obtains a small sample of cells and mucus from the cervix and examines it under a microscope to check for abnormalities. There are two main types of abnormalities: low-grade lesions and high-grade lesions. Low-grade lesions are fairly common and usually resolve naturally within two years; thus, if a pap smear detects a low-grade lesion, a gynecologist will most often recommend a follow-up appointment in six months to monitor the lesion. There is, however, a 12-16% chance that a low-grade lesion will progress into a more serious high-grade lesion. Should this occur, the gynecologist will perform a colposcopy in which he/she examines the cervix using a specialized microscope and may take a biopsy. High-grade lesions have a relatively high chance of developing into cervical cancer and must be treated aggressively. The three most common types of treatment are freezing, laser burning, or electric excision of the abnormal cervical tissue. If advanced cervical cancer develops, it is treated either by chemotherapy or by hysterectomy (the removal of the uterus and cervix).

Cancer-causing HPV usually causes no pre-cancerous symptoms in males. Thus, males are carriers and often unknowingly infect their sexual partners. Fortunately, most individuals (both male and female) are able to eliminate the virus naturally without experiencing any issues. There is no male test for HPV and it is very difficult to know if a man has contracted an asymptomatic (a non-wart causing) strain of HPV.



There are currently three approved HPV vaccines available in the United States, Cervarix®, Gardasil®, and Gardasil® 9. All of the vaccines protect against HPV types 16 and 18, which are most commonly known to be cancer causing. Cervarix® is generally only used for females. Gardasil® is a vaccine for both males and females introduced in 2006 that protects against two additional types of HPV (types 6 and 11) which are known to cause anogenital warts. In 2014, Gardasil® 9 was approved. Gardasil® 9 is a vaccine that, in addition to the strains accounted for in Gardasil®, protects males and females against five other types of HPV that can cause vulvar, cervical, vaginal, and anal cancer.1

A syringe and a clear tube.

HPV vaccinations consist of three separate injections over the course of about six months. Vaccinations are intended for males up to the age of 21 and females up to the age of 26, with special recommendations for gay and bisexual men and both males and females with weak immune systems. The CDC recommends that males and females be vaccinated when they reach the age of 11 or 12, but children as young as 9 years old can also receive the vaccine. It is best for males and females to be vaccinated as early as possible for several reasons. The most important reason is that HPV vaccines are most effective when they are administered before the patient has been exposed to the virus. The virus occurs most commonly in people in their late teens to early 20’s, so children should be vaccinated before they reach their teen years. Also, early adolescents should be vaccinated before they become sexually active. Another reason for early vaccination is that the vaccine is more effective on the immune systems of younger people than post-pubescent people. Even individuals who have already begun having sex are encouraged to get the vaccine. Females should strongly consider Gardasil® or Gardasil® 9 to protect themselves mainly against anogenital warts and cervical cancer. Males are not at risk for cervical cancer but should receive the vaccination to protect themselves from anogenital warts and penile or anal cancers that are caused by the same HPV types that lead to cervical cancer in females. Another reason males are encouraged to get HPV vaccines is so that they can avoid facilitating the spread of HPV to their future sexual partners. There are no current methods to screen males for HPV in the same way that females are screened, so it is extra important that males take preventative measures to reduce their likelihood of contracting the virus in the first place.1

HPV vaccines have been shown to be extremely effective at protecting against 70-80% of cancer causing HPV types for several years. Side effects that accompany this vaccination are uncommon and mild, and include pain and swelling at the injection site, fever, headache, nausea, muscle and joint pain, and tiredness. Vaccines do not give patients HPV or lead directly to the development of cancer. Although vaccines protect against the most problematic types of HPV, they do not protect against all types, so it is still necessary to be tested for the virus often and take other preventative measures.1

Cancer Screenings

Routine cancer screenings in the form of an annual pap smear and pelvic exam are recommended for females who are sexually active and/or aged 21-65.1 Around 30% of cervical cancer cases are caused by HPV types other than those included in the vaccine, so annual pap smears are still necessary even for those who have received the vaccine. To read more about what happens during a pap smear, click here.

Safe Sex Practices

A female condom and a male condom.

In addition to getting vaccinated and routine check-ups, having safe sex is an important strategy for reducing the risk of contracting HPV. Condoms and dental dams are effective at preventing the transmission of most sexually transmitted infections (STIs). Make sure you are using condoms correctly every time you have sex, even oral sex. Unfortunately, HPV can be transmitted via contact with genital areas that are not covered by condoms, so it is possible to contract the virus even when using protection. Still, every small bit of prevention is safer than none at all. Another HPV prevention method is participating in monogamous sexual relationships.1 If you are only having sex with one person for a given period of time, it is much easier to communicate with your partner about getting tested for HPV. If you are the only person your partner is having sex with, you can take comfort in knowing that you both are aware of one another’s status and can be easily updated if anything changes. Regardless of how many sexual partners you have, it is important for your safety that you talk with them about getting tested, and that you do not engage in unprotected sex with anyone you do not trust to have been recently tested for HPV and other STIs. Remember to thoroughly clean your sex toys after every use. If you believe you have contracted HPV or any other STI, it is best not to engage in any kind of sexual contact with anyone until you have seen a doctor to get diagnosed. If you or your partner has been diagnosed with HPV, keep in mind that this does not mean that either of you have done anything wrong, or that your sexual relationship will be affected. You may be advised to see a doctor periodically until the infection clears up to make sure that no complications arise.

Concluding Remarks

An HPV pink medical device.

In conclusion, Human Papillomavirus (HPV) is almost unavoidable. After all, with nearly 80 million Americans currently affected and 14 million new infections each year, it can be expected that any given sexually active individual will experience an HPV infection at least once in their lifetime. Most of the time, HPV is nothing to worry about and the human body can fight it off on its own. However, when the virus leads to warts or cancer, the effects can be uncomfortable and even dangerous. Luckily, there are steps that can be taken to reduce the risk of spreading HPV. If you take the above-mentioned preventative steps and make sure to communicate with all sexual partners about getting tested as well as keeping up a healthy lifestyle, HPV may not ever have to be a problem in your life.


1. “Questions and Answers.” Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 28 Dec. 2015. Web. 20 Apr. 2016.

2. “Human Papillomavirus (HPV) and Cervical Cancer.” World Health Organization. World Health Organization, n.d. Web. 20 Apr. 2016.

3. Smith RA, Cokkinides V, Brooks D, Saslow D, Brawley OW. Cancer screening in the United States, 2010: a review of current American Cancer Society guidelines and issues in cancer screening. CA Cancer J Clin. 2010;60:99-119.

4.  NCCN Clinical Practical Guidelines in Oncology: Cervical cancer. V.1.2010. National Comprehensive Cancer Network, Inc. Accessed October 10, 2011.

Last updated 3 May 2016.