Genital warts are caused by the human papillomavirus, commonly known as HPV. Two specific strains, HPV 6 and HPV 11, are responsible for the vast majority of cases. These are classified as “low-risk” strains because they rarely lead to cancer, but they are highly contagious and very common. More than 42 million Americans currently carry disease-causing types of HPV, with roughly 13 million new infections occurring each year.
How HPV Spreads
HPV is most commonly spread during vaginal or anal sex. It also spreads through close skin-to-skin touching during sexual contact, which means penetration isn’t strictly necessary for transmission. The virus enters the body through tiny breaks or micro-abrasions in the skin or mucosal surfaces of the genital area, where it infects cells and can eventually trigger the growth of warts.
One of the trickiest things about HPV is that it spreads even when no warts are visible. Sexual partners tend to share HPV whether or not either person shows any signs of infection. The virus can also still be transmitted after warts have been treated and removed, because HPV remains present in surrounding skin cells. This silent transmission is a major reason the virus is so widespread.
Why Warts Don’t Appear Right Away
After exposure to HPV, visible warts don’t show up immediately. The incubation period ranges from a few weeks to many months. Some people carry the virus for a long time without ever developing warts at all. This delay makes it difficult, and often impossible, to pinpoint exactly when or from whom you contracted the infection. It also means a current partner isn’t necessarily the source; the virus could have been acquired from a previous relationship months or even years earlier.
Risk Factors That Increase Your Chances
Anyone who is sexually active can get genital warts, but certain factors raise the likelihood:
- Not being vaccinated against HPV. The vaccine is the single most effective form of prevention.
- Having unprotected sex or multiple partners. More exposure opportunities mean higher risk.
- A history of other sexually transmitted infections. Prior STIs can indicate higher overall exposure risk and may compromise mucosal barriers.
- A weakened immune system. Conditions like HIV, or medications taken after an organ transplant, reduce your body’s ability to suppress the virus. People with healthy immune systems are more likely to clear HPV on their own without ever developing warts.
- Becoming sexually active at a young age. Earlier sexual debut increases cumulative lifetime exposure to HPV.
Low-Risk vs. High-Risk HPV Strains
Not all HPV strains behave the same way. HPV types are divided into two categories: low-risk and high-risk. The low-risk types, primarily HPV 6 and 11, cause warts but rarely lead to cancer. There are 12 identified high-risk types (including HPV 16 and 18) that can cause cervical, anal, throat, and other cancers. These high-risk strains typically don’t produce visible warts, which is why having genital warts doesn’t mean you’re at elevated cancer risk, and why not having warts doesn’t mean you’re in the clear for high-risk HPV.
It’s possible to be infected with more than one HPV type at the same time. A person could carry a low-risk strain that causes warts alongside a high-risk strain that causes no symptoms at all. This is one reason routine screening (like Pap smears or HPV tests) matters independently of whether warts are present.
Can You Get Genital Warts From Toilet Seats or Towels?
This is one of the most common questions people have, and the answer is reassuring. While HPV DNA has been detected on inanimate objects like towels and surfaces, there is no evidence that this is a real method of transmission. Genital warts are spread through direct skin-to-skin sexual contact, not from toilet seats, swimming pools, or shared clothing.
Transmission During Childbirth
In rare cases, a mother with HPV can pass the virus to her baby during delivery. One study found that about 7% of newborns had detectable HPV at birth, most commonly in the eyes, mouth, or genital area. The reassuring finding: all HPV-positive infants in that study cleared the infection before six months of age. About 85% of those babies carried the same HPV strain detected in their mother’s vaginal samples during pregnancy, confirming the route of transmission.
How the HPV Vaccine Prevents Genital Warts
The current HPV vaccine protects against nine strains, including HPV 6 and 11, the two low-risk types behind most genital warts. Clinical trials found the vaccine to be 99% effective at preventing genital warts caused by these strains. It also covers seven high-risk cancer-causing types, making it protective against roughly 80% of cervical cancers and most other HPV-related cancers.
The vaccine works best when given before any exposure to HPV, which is why it’s routinely recommended starting at age 11 or 12. But it still provides benefit for people vaccinated later, up to age 26 for most individuals and up to 45 in some cases, depending on prior exposure and individual risk. If you’ve already been infected with one HPV strain, the vaccine still protects against the other strains it covers.
Condoms reduce the risk of HPV transmission but don’t eliminate it entirely, because the virus can infect skin that a condom doesn’t cover. Vaccination remains the most reliable preventive tool available.