Human papillomavirus (more commonly known as HPV) is the most common sexually transmitted disease in North America and one of the most common worldwide. It can cause a number of topical symptoms, including genital warts–small growths that typically disappear on their own after several weeks. There are over 100 different strains of HPV, and more than half of sexually active adults will contract the virus at some point in their lives.

Some lubricants and other sexual health products use a red seaweed extract called carrageenan to limit chances of HPV transmission, and if you’re looking for a lubricant for safe sex, carrageenan appears to have some serious benefits. Before you buy, however, you should understand exactly what carrageenan does (and doesn’t) do.

Why is HPV a Problem, and Can Carrageenan Help?

While HPV is mostly harmless on its own, some strains are carcinogenic. According to the Centers for Disease Control and Prevention, current research suggests that HPV is responsible for more than 90 percent of cervical and anal cancers. The virus may also cause penile, vaginal, and vulvar cancers, as well as cancers of the head and neck.

The CDC says that 90 percent of infections go away after two years without treatment, but given the increased cancer risks, you certainly don’t want to take chances with HPV.

Many people never realize that they’re infected with HPV, as the virus doesn’t always cause symptoms. Anytime you have sex with a new partner, you’re exposing yourself to a potential infection, but you may limit your risks by using a lubricant with carrageenan.

A 2006 study published by the National Cancer Institute showed that carrageenan limits human papillomavirus in vitro, and it’s remarkably effective; while the study notes that clinical trials are necessary, carrageenan appears to be three times as effective as heparin (another chemical widely accepted as an HPV killer).

Carrageenan works by stopping human papillomavirus from binding to cells, thereby limiting the chances of infection. However, lubricants use carrageenan in wildly different amounts, so manufacturer claims aren’t always reliable. Other lubricant ingredients could also conceivably limit carrageenan effectiveness, although there’s not yet evidence of this.

Other Ways to Reduce Your Risks of HPV

While lubricants with carrageenan may potentially inhibit the human papillomavirus, they can’t provide complete protection. More importantly, carrageenan doesn’t protect against other sexually transmitted infections, so you should always use condoms when having sex.

Condoms provide some protection against HPV, but they’re not totally effective since any skin-on-skin contact could transmit the virus. The HPV vaccine provides excellent protection from two of the most deadly strains of the virus (types 16 and 18), and it’s the safest way to protect yourself from HPV’s potential carcinogenic effects.

While we need more clinical trials to definitively declare lubricants with carrageenan as an effective prevention strategy against HPV, the current research is very promising. The 2006 study referenced above notes that “some [products with carrageenan] block HPV infectivity in vitro, even when diluted a million-fold.”

Here’s the bottom line: don’t use your lubricant as your a form of protection, but if you’re looking for a lube ingredient that will supplement your safe sex practices, carrageenan is certainly worthy of consideration.