You have to use protection, whether you're HIV-positive or you're in a mixed-status couple, in which one person has HIV and the other doesn't.
Use condoms every time you have sex. Unprotected sex is the most common way of spreading the virus. Male and female condoms dramatically lower the chances of transmitting HIV.
Use protection with oral sex, too. Oral sex can still transmit HIV. Always use a condom or dental dam.
Cut other risk factors. Transmitting HIV is more likely if you have multiple sex partners, have other STDs, or use injectable drugs.
What about kissing? Since HIV is not in saliva, most kissing is perfectly safe. There's a remote risk that if you or your partner had a mouth sore, French kissing could spread HIV. But it's extremely unlikely, experts say.
What about everything else? Remember that HIV is only in certain bodily fluids -- like blood, semen, and vaginal and anal secretions. To infect someone else, that fluid has to get into the person's body, usually through a mucus membrane or cut.
So, other contact, like cuddling and hugging are safe. And you can satisfy each other sexually in safer ways, using your hands or your bodies.
What if you and your partner both have HIV? You still need to use protection. You could catch a different strain of HIV from your partner, which could make your disease worse or mean that you need to change medications.
Treatment as Prevention
If you have HIV, one of the most important ways you can protect yourself and your partner is to stick with your antiretroviral treatment. Treatment can reduce the amount of virus in your body called the viral load, so much that it doesn't show up in tests.
"If you have your viral load down to an undetectable level, the risk of giving HIV to someone else is quite low," says Michael Melia, MD. He's an assistant professor at Johns Hopkins University School of Medicine.
That said, you shouldn't rely on treatment alone as protection, Melia says.
"We always tell people to use more than one form of protection, like treatment along with a condom," says Brad Hare, MD. He's the director of the HIV/AIDS Clinic at San Francisco General Hospital. While no one form of protection is 100% effective, combining them can strengthen your defenses.