Carrageenan is a polysaccharide created from certain types of seaweed. It is added to some sexual lubricant products with claims prevent the spread of sexually transmitted diseases. There are no FDA studies which back up the claim when used in personal lubricants.

Manufacturers claim that carrageenan works well as a personal lubricant additive to kill viruses such as herpes simplex virus 2 (HSV-2) and human papillomavirus (HPV), which can cause genital warts and some types of ovarian cancer. Carrageenan is a considered a safe additive in standard dosages.