Can I transmit HIV if I have an undetectable viral load?

HIV medicine lowers the amount of virus (viral load) in your body, and taking it as prescribed can make your viral load undetectable.

Sex Partners

If your viral load stays undetectable, you have effectively no risk of transmitting HIV to an HIV-negative partner through sex.

Needle-Sharing Partners

We don’t know whether getting and keeping an undetectable viral load prevents HIV transmission through sharing needles or other injection drug equipment. It very likely reduces the risk, but we don’t know by how much. Never share needles and other equipment to inject drugs.


If a woman living with HIV can take HIV medicine as prescribed throughout pregnancy, labor, and delivery and if HIV medicine is given to her baby for 4-6 weeks after delivery, the risk of transmission from pregnancy, labor, and delivery can be reduced to 1% or less. We don’t know if a woman living with HIV who has her HIV under control can transmit HIV to her baby through breastfeeding. While we do not yet know if or how much being undetectable or virally suppressed prevents some ways that HIV is transmitted, it is reasonable to assume that it provides some risk reduction. The current recommendation in the United States is for mothers with HIV to avoid breastfeeding their infants.

Treatment is a powerful tool for preventing sexual transmission of HIV. But it works only as long as you keep an undetectable viral load.

Consider taking other actions to prevent HIV, like using condoms or pre-exposure prophylaxis (PrEP), if you or your partner wants added peace of mind. Taking these other actions can be useful, especially if you

  • Have trouble regularly taking HIV medicine,
  • Have an increased viral load, or a load of 200 copies/ml of blood or greater,
  • Haven’t had a recent test (last 3-4 months) that shows the viral load is undetectable,
  • Missed some doses since the last viral load test, or
  • Have stopped taking HIV medicine in the past and may choose to do so again.

Also use condoms if either partner is concerned about getting or transmitting other STDs.

If I have an undetectable viral load, do my partner and I need to use anything else to prevent sexual transmission of HIV?

Getting and keeping an undetectable viral load prevents HIV transmission during sex. But there are situations when either partner may consider adding other prevention options like condoms or pre-exposure prophylaxis (PrEP):

  • Either partner wants protection from other STDs.
  • The partner with HIV missed some doses of medicine since the last viral load test, stops taking their medicine, or has trouble taking it every day.
  • The partner with HIV is having difficulty keeping an undetectable viral load.
  • Either partner is unsure if the person with HIV has an undetectable viral load.
  • Either partner wants added peace of mind.

My viral load is not undetectable. How can I prevent HIV transmission?

Getting and keeping an undetectable viral load is the best thing you can do to stay healthy. Most people can get the virus under control within six months. But some people face challenges that make it hard to stick to a treatment plan, and a few people cannot get an undetectable viral load even though they take HIV medicine as prescribed.If your viral load is not undetectable—or does not stay undetectable—you can still protect your partner by using other prevention methods. The following actions are highly effective for preventing HIV:

  • Use condoms the right way every time you have anal or vaginal sex.
  • Choose sexual activities with little to no risk, like oral sex. You could also use condoms or dental dams with oral sex to lower the risk even more.
  • Your partner can take medicine to prevent HIV, called pre-exposure prophylaxis (PrEP). Your partner will need to take PrEP every day for around 7 days before it becomes as effective as it can be for receptive anal sex and around 20 days for receptive vaginal sex,* and they’ll need to keep taking PrEP every day.
  • Never share syringes or works to inject drugs.

If your partner or you have other sexually transmitted diseases (STDs), getting treatment for those STDs can also help lower your risk of transmitting HIV. People who are HIV-positive and have another STD may have an increased concentration of HIV in their semen and genital fluids, which might make them more likely to transmit HIV. People who are HIV-negative and have another STD may have irritation that makes it easier for HIV to enter their body during sex, or inflammation in their body may increase the number of cells that HIV can target.Keep in mind that your greatest chance of transmitting HIV is when you are the insertive partner (top) during anal sex. But it’s also possible to transmit HIV when you are the receptive partner during anal sex or either partner during vaginal sex.

* The number of days depends on the person’s HIV risk behaviors: For receptive anal sex, an HIV-negative person needs to take PrEP 7 days in a row (and keep taking it) to get the most protection. For receptive vaginal sex and injection drug use, they need to take PrEP 20 days in a row (and keep taking it) to get the most protection. We don’t know yet how long it takes to get the most protection for insertive anal or insertive vaginal sex. For more information, see page 46 in the PrEP guidelines pdf icon[PDF – 2 MB].

How do I talk to my partner about safer sex?

Whether you have HIV or want to take precautions against getting HIV, here are some conversation starters to help you begin talking about safer sex options with your partners include:

  • I really like you, and like where this is going, but before we go any further, there’s something I want to tell you. I’m HIV-positive.
  • Let’s start talking about ways to keep each other healthy and safe. When was the last time you were tested for HIV?
  • Did you know that there are medicines that you can take that can further reduce the chance of you getting HIV? Have you heard of PrEP (pre-exposure prophylaxis)? Maybe we should talk to our doctors to see if it’s right for us.
  • Can we talk about sex? Safer sex is really important to me.
  • So we haven’t really talked about it, but can we agree that when the time comes, we’ll use condoms to keep each other safe?
  • I know we just met and we don’t know everything about each other, but you should know that practicing safer sex is really important to me. When is the last time you were tested for HIV and other sexually transmitted diseases?

For partners that are both living with HIV:

  • If we’re going to have sex, let’s get tested for other STDs together before we take that step.
  • Getting an STD could really compromise our health. Let’s stay healthy and get tested for STDs regularly.
  • Let’s talk about how we can practice safer sex so that we don’t increase our chances of getting an STD or a new strain of HIV.