The U.S. Food and Drug Administration issued a final rule Tuesday requiring manufacturers of nonoxynol-9, also known as N9, to add a warning to the product’s label.

The health agency said that the warning had to make clear that the over-the-counter products, including diaphragms, contraceptive gels, foams, films and inserts do not protect against infection by the human immunodeficiency virus that causes AIDS or against other sexually transmitted diseases.

"FDA is issuing this final rule to correct the misconceptions that the chemical N9 in these widely available stand-alone contraceptive products protects against sexually transmitted diseases," Janet Woodcock, FDA's deputy commissioner for scientific and medical programs, said.

Moreover, the FDA said that N9 may irritate the vagina and rectum, which may increase the risk of contracting HIV/AIDS from an infected partner.

The new warning comes 4 years after a study from Africa and Thailand showed that women using a contraceptive gel product containing N9 weren’t protected against HIV and other STDs. These women had more chances to develop HIV infection than women using a placebo gel.

"Clinical research has shown that N9 provides no protection against sexually transmitted diseases to the woman if her sexual partner is infected with an STD pathogen or HIV," says Woodcock, who is the FDA's deputy commissioner for scientific and medical program, chief medical officer, and acting director for the FDA's Center for Drug Evaluation and Research, according to WebMD.

Moreover, the FDA advised consumers to protect themselves from the transmission of STDs and HIV, by practicing abstinence, having a monogamous relationship or using condoms consistently and correctly.