The most common way people are infected with HIV is by having sex with an infected person. You can't tell by looking at a person whether they have HIV, so you have to protect yourself -- and your sex partner.
Don't have unprotected sex outside marriage or a committed relationship. If you or your partner has ever had unprotected sex -- or if either of you uses injected drugs -- the only way to be sure you don't have HIV is to get tested. Have two HIV tests six months apart, with no new sex partners or injection drug use between tests.
You can't get HIV if your penis, mouth, vagina, or anus doesn't touch another person's penis, mouth, vagina, or anus. Kissing, erotic massage, and mutual masturbation are safe sex activities.
You can greatly reduce your risk by using a latex or polyurethane condom during sex. Don't use natural-skin condoms -- they prevent pregnancy, but they don't prevent infections. Put on the condom on as soon as you or a male partner has an erection, not just before ejaculation. Use a lubricant -- but never use an oil-based lubricant with a latex condom. The female condom, called a vaginal pouch, also protects against disease.
Oral sex without a condom or latex dam is not safe, but it's far safer than unprotected intercourse.
The HIV drug Truvada has been approved for use in those at high risk as a way to prevent HIV infection. It's to be used in conjunction with safe sex practices.
Drug Use and HIV Prevention
Using drugs increases your HIV risk. If you're not ready to stop taking drugs, you can still reduce your risk of getting HIV/AIDS. Here's how:
Don't have sex when you're high. It's easy to forget about safe sex when you're on drugs.
If you use drugs, don't inject them.
If you inject drugs, don't share the equipment. This includes every piece of it: needles, syringes, cookers, cotton, and rinse water. Some states have needle-exchange programs where you can trade in dirty equipment for new equipment.