Human papillomavirus, or HPV, is a group of more than 200 related viruses and the most common sexually transmitted infection in the world. Most sexually active people will pick up at least one HPV infection during their lifetime, and roughly one in three men worldwide carry at least one genital HPV type at any given time. The good news: your immune system clears the vast majority of these infections on its own, and a highly effective vaccine can prevent the strains most likely to cause cancer or genital warts.
High-Risk vs. Low-Risk Strains
Of the 200-plus HPV types identified so far, only a small fraction cause serious health problems. Scientists divide them into two broad categories based on what they do in the body.
Low-risk strains, particularly types 6 and 11, are the ones behind genital warts and low-grade precancerous changes that rarely progress further. These warts can appear as small, flesh-colored bumps or clusters in the genital or anal area. They’re not dangerous, but they can be uncomfortable and stressful to deal with.
High-risk strains are a different story. Types 16 and 18 are the most well-known, responsible for the majority of HPV-related cancers. But they’re not the only ones. Types 31, 33, 35, 39, 45, 51, 52, 56, 58, and 59 also carry elevated cancer risk. In total, 12 high-risk HPV types have been identified. These strains don’t cause visible symptoms. Instead, they can quietly trigger cell changes over years or decades that, if not caught by screening, may develop into cancer of the cervix, anus, throat, penis, vagina, or vulva.
How HPV Spreads
HPV passes from person to person through close skin-to-skin contact during sex, including vaginal, anal, and oral sex. It doesn’t require penetration to spread. Someone carrying the virus can transmit it even when they have no visible warts or any other signs of infection, which is a major reason it circulates so widely. Condoms reduce the risk but don’t eliminate it completely, because HPV can infect skin that a condom doesn’t cover.
What Your Immune System Does With HPV
Most HPV infections are temporary. Your immune system recognizes the virus and eliminates it without you ever knowing it was there. About 66% of infections clear within 12 months, and that number climbs to roughly 90% by 24 months. For oral HPV infections, approximately 40% clear within just six months.
The infections that don’t clear are the ones that matter. When a high-risk strain persists for years, it can gradually alter the DNA of infected cells, pushing them toward precancerous changes and eventually cancer. This process is slow, typically unfolding over a decade or more, which is why regular screening can catch problems long before they become dangerous.
Screening Guidelines by Age
There is no approved HPV test for men, and no routine screening is recommended for oral or anal HPV in the general population. Current screening guidelines focus on cervical cancer prevention in women.
For women aged 21 to 29, the recommended approach is a Pap smear every three years. This test looks for abnormal cell changes on the cervix rather than testing for the virus itself. Starting at age 30, women have more options: a Pap smear every three years, a high-risk HPV test alone every five years, or both tests together (called cotesting) every five years. All three strategies offer a reasonable balance of accuracy and practicality. Screening generally stops at age 65 for women with a history of normal results.
The HPV Vaccine
The current HPV vaccine, Gardasil 9, protects against nine strains: the two low-risk types that cause most genital warts (6 and 11) and seven high-risk types linked to cancer (16, 18, 31, 33, 45, 52, and 58). Together, these cover the strains responsible for the large majority of HPV-related disease.
The CDC recommends vaccination at age 11 or 12, though it can start as early as 9. For anyone who wasn’t vaccinated in childhood, the vaccine is recommended through age 26. Adults between 27 and 45 can also receive it after discussing the potential benefit with a healthcare provider, though fewer people in that age range will benefit since most have already been exposed to common strains.
The number of doses depends on when you start. Children who begin the series between ages 9 and 14 need only two shots, spaced 6 to 12 months apart. Anyone starting at 15 or older, or anyone with a weakened immune system, needs three doses spread over about six months. The vaccine works best when given before any exposure to HPV, which is why the recommended age is well before most people become sexually active.
Living With an HPV Diagnosis
An HPV diagnosis can feel alarming, but context helps. Given how common the virus is, a positive result means you’re in the majority of sexually active adults, not the minority. There is no treatment that eliminates HPV from your body. Instead, treatment targets the problems HPV can cause: genital warts can be treated with topical solutions or minor procedures, and precancerous cervical changes can be monitored or removed before they progress.
For most people, the practical takeaway is straightforward. If you’re eligible for the vaccine, getting vaccinated is the single most effective thing you can do. If you’ve already been exposed, keeping up with recommended screening catches the rare cases where a persistent infection starts causing trouble, giving you and your provider plenty of time to act before cancer ever develops.