The agency also wants packaging to advise that condoms that use a common spermicidal lubricant should not be used by people at risk of catching HIV.
In proposed rules posted on its Web site, the Food and Drug Administration said the changes to male condom labels would provide people with more precise information on how well condoms work. They would apply to latex condoms, which make up about 98 percent of the market; rules for other condoms are forthcoming.
The FDA would not insist condom manufacturers use FDA-provided language, but they would have to include the information in some form on their packages.
"More accurate information about the risks and benefits of condom use with respect to STD transmission can lead to better choices by individuals who seek to protect themselves against these infections and potentially to reduced transfer of STDs," the FDA said.
Condom packages now generally note they are effective in reducing the chance of pregnancy and getting an STD, particularly HIV, from intercourse.
Under the proposed rules, condom packages would say that they are thought to be less effective against certain STDs, including herpes and human papilloma virus, because those diseases can be transmitted through skin-to-skin contact in places not covered by a condom. However, studies have shown condom use does reduce the chances of a person suffering from some of the worst effects of human papilloma virus, or HPV, which include genital warts and cervical cancer.
In addition, packages of condoms that use nonoxynol-9, which kills sperm, would come with a recommendation that they should not be used by people at risk of catching HIV, the virus that causes AIDS. The spermicide can irritate the vagina or rectum, leading to a greater chance that HIV can be transmitted from an infected partner.
Packages of condoms with nonoxynol-9 already include a statement noting the extent of the chemical's effectiveness in decreasing the risk of pregnancy beyond that of the condom itself is uncertain.
The FDA considered, and discarded, suggestions to include social or public health-related advice on condom packages, the agency said.
Some activists had worried the FDA would propose far greater changes to current guidelines and exaggerate the failure rate of condoms in accordance with the wishes of some social conservatives. But that didn't happen.
"I would hope that the clarifying language marks the start of a real commitment to educating the American public about the importance of condom use, and public health programs to help people use them correctly and consistently," said Julie Davids, executive director, of the Community HIV/AIDS Mobilization Project. She commended FDA "for sticking to sound public health rather than scare tactics."
The FDA said the financial impact on manufacturers to change their labels would be minimal. A spokeswoman for the Trojan brand of condoms said the company was reviewing the guidelines but declined to discuss them further.
The proposed rules are the result of a review mandated by Congress in 2000. Sen. Tom Coburn, R-Okla., said the proposed language falls far short.
"While I am encouraged that the FDA finally has recognized the inaccurate claims about contraceptives containing nonoxynol-9 and the exaggerated claims of condom protection against sexually transmitted diseases, the agency continues to promote inconclusive assurances that put women unknowingly at risk for cervical cancer, or worse," he said.
Coburn, a physician, dismissed the notion that condoms protect against cervical cancer as speculation, saying there wasn't enough science to prove it.
"The FDA should stop playing political games with the health and lives of Americans and immediately comply with the law by ensuring only medically accurate information that is irrefutable on condom labels," he said.
When latex condoms are used every time and put on early enough, they reduce chances of pregnancy over a one-year period to 3 percent, compared with 85 percent without birth control. Likewise, condoms cut risk of HIV infection by about 80 percent, to less than a 1 percent chance of infection per year.
According to the National Institutes of Health, condoms are impermeable to the smallest viruses and only break or slip off 1 percent to 2 percent of the time. But surveys show people don't always use them properly or consistently. Roughly 12 million Americans each year contract an STD.
Once published in the Federal Register — expected in the coming days — the rules will be open to 90 days of public comment.