HPV, or human papillomavirus, is the most common sexually transmitted infection in the world. About 85% of people will get an HPV infection at some point in their lifetime. It spreads through skin-to-skin contact, most often during sexual activity, and while the majority of infections clear on their own without causing problems, certain strains can lead to genital warts or cancer.
Low-Risk vs. High-Risk Strains
There are over 200 types of HPV, but the ones transmitted sexually fall into two categories: low-risk and high-risk. Low-risk types rarely cause anything serious. They’re the strains responsible for genital warts, which appear as small bumps (or clusters of bumps) around the genitals, anus, mouth, or throat. These warts can be flat or raised, small or large, and sometimes have a cauliflower-like texture. They’re not dangerous, but they can be uncomfortable or cosmetically bothersome.
High-risk HPV is a different story. There are 12 high-risk types, and two of them, HPV 16 and HPV 18, are responsible for most HPV-related cancers. These strains don’t cause warts or any visible symptoms on their own. Instead, if the infection lingers for years without clearing, it can slowly cause cell changes that eventually become cancerous. The cancers linked to high-risk HPV include cervical, anal, throat, penile, vaginal, and vulvar cancers.
How HPV Spreads
HPV is transmitted through direct skin-to-skin contact, primarily during vaginal, anal, or oral sex. It doesn’t require an exchange of bodily fluids the way some other infections do. The virus lives in the skin and mucous membranes, so contact with an infected area is enough. This means condoms reduce the risk but don’t eliminate it entirely, since they don’t cover all the skin that may carry the virus.
You can get HPV the very first time you have sexual contact with another person. Someone can also carry and transmit the virus without knowing it, because most people with HPV never develop symptoms. There’s no reliable way to know who has it just by looking, and the infection can be passed along even when no warts or other signs are present.
What Happens After Infection
Most people with HPV never develop symptoms or health problems from it. The immune system typically clears the virus on its own within one to two years. Research tracking young women with HPV 16 and HPV 18 infections found that about 69% cleared HPV 16 and 85% cleared HPV 18 within 24 months. By four years, those numbers rose to roughly 82% and 90%, respectively.
The concern is with infections that don’t clear. When a high-risk strain persists for many years, it can cause precancerous cell changes that, left undetected, may eventually become cancer. This process is slow, often taking a decade or more, which is why routine screening is so effective at catching problems early. When a persistent infection does progress, symptoms may include unusual bleeding, lumps, or pain at the site of infection.
Screening and Detection
For people with a cervix, screening is the primary tool for catching HPV-related problems before they become serious. The two main screening methods are cytology (commonly known as a Pap smear), which looks for abnormal cell changes, and an HPV DNA test, which checks directly for the presence of high-risk strains.
Current guidelines recommend Pap smears alone every three years for women aged 21 to 29. HPV testing isn’t recommended for this younger group because infections are so common and so frequently clear on their own that a positive result would lead to unnecessary follow-up procedures. For women aged 30 to 65, the options expand: a Pap smear every three years, an HPV test alone every five years, or both tests together every five years. The HPV test is slightly more sensitive at detecting precancerous changes, though it also leads to more follow-up procedures for findings that may resolve without treatment.
There is currently no approved HPV screening test for men, and no routine screening recommendation for HPV-related cancers at non-cervical sites like the throat or anus in the general population.
How the Vaccine Works
The HPV vaccine is the most effective way to prevent infection. It protects against the high-risk strains most likely to cause cancer (including HPV 16 and 18) as well as the low-risk strains that cause most genital warts. The vaccine works best when given before any exposure to the virus, which is why it’s routinely recommended at age 11 or 12, though it can be given as early as age 9.
The number of doses depends on when you start. Children who receive their first dose before age 15 need only two shots. Those who start at 15 or older, or who have certain immune conditions, need three doses. The vaccine is recommended for everyone through age 26. For adults 27 to 45, it’s available but typically involves a conversation with a healthcare provider about whether the benefit is meaningful given likely prior exposure.
The vaccine is preventive, not therapeutic. It protects against new infections but doesn’t treat or clear an HPV infection you already have. That said, even someone who has been exposed to one strain of HPV can still benefit from protection against the others included in the vaccine.
Reducing Your Risk
Beyond vaccination, a few practical steps lower your chances of getting or spreading HPV. Condoms and dental dams reduce skin-to-skin contact during sex, though they don’t cover every area where the virus may be present. Limiting the number of sexual partners also reduces cumulative exposure, simply because HPV is so widespread that more partners means more opportunities for contact with the virus.
For people with a cervix, keeping up with recommended screening schedules is critical. Cervical cancer is one of the most preventable cancers precisely because it develops slowly and screening catches precancerous changes years before they become dangerous. The combination of vaccination and regular screening has made cervical cancer rates drop significantly in countries with strong public health programs.