Q and A


Is reinfection a risk if two HIV positive people are undetectable?

What are the risk involved in two HIV+ people in a couple who are both on medications and are undetectable to re infect each other during sex without a condom?

One partner (myself) has been living with HIV for a decade while my partner has been living with it less than 6 months.

I read re infection tends to be more common within the first few years of infection.

So what does the science say about two undetectable people having condomless sex?



Thanks for your question.

The two main risks from not using a condom are pregnancy and other STIs.

If these are not a concern for you, then there is no risk. This is mainly because having an undetectable viral load on treatment makes you so dramatically less infectious that HIV transmission becomes zero risk.

Even if reinfection occurred, due to viral rebound, this would only be important if one of you had drug resistance. Because your viral loads are both undetectable, neither of you have resistance to your current meds.

So long as you continue to take meds carefully and not miss doses, there is no reason that you will develop resistance in the future either.

Although it can seem strange if you are used to using condoms, many people in your situation find that not having to always use condoms can have a positive impact on their quality of life.

Please see the reports from 2017 saying that U=U (Undetectable = Untransmittable). This shows that HIV cannot be transmitted even if you don’t use condoms.

This Q&A was updated in July 2019 to an answer posted in September 2014.


  1. Lisa Thorley

    Hi Letica,

    The above discusses reinfection.
    Weight loss can be due to a number of things, of which stress is one. Do you know what your CD4 count is? Is there a support group near to where you live?

  2. Leticia

    Hi I tested HIV positive a month ago and started my treatment,me and my boyfriend been together for 4 months and he tested positive two weeks ago and it seems like I’m the one who brought the virus.I m losing too much weight because we still don’t use a condom and he s not on meds he think I’m stressed.we never been to counselling together and I care about him.won’t we reinfect each other even though we are faithful to each other

  3. Lisa Thorley

    Hi Thabo,

    There’s no reason at all why you can’t start trying for a family. For more info please see Q6 here:


  4. thabo

    I’m HIV positive and my wife is positive too and we started taking our arvs so is it possible to have a baby?

  5. Lisa Thorley

    Hi Steven,

    If you’re having problems with your sinuses or breathing problems this is something that you should talk to a doctor about.

    With regards to treatment, the World Health Organisation recommend that everyone should be on meds. Therefore, if you’re ready to start, then yes. However, this is more important if you have a low CD4 count. Do you know what yours is?

  6. Steven

    If you have HIV and you have sinuses would you advise me to start treatment … also have breathing problems?

  7. Lisa Thorley

    Hi Pulane,

    Even if your husband doesn’t know his status, your viral load and CD4 count will not affected.This is because you’re on treatment. Its the treatment that is helping your HIV.

    With regards to your husband, if he isn’t positive, you are protecting him from contracting HIV because you’re on treatment. Basically when someone is on treatment, and their viral load is undetectable, the risk of transmission is close to zero. Please see the results of the PARTNER study for more info:


    If you want to have a baby, there’s no reason why being positive should be an issue. Many women from all over the world who are positive have kids.

    Because you’re thinking about having a baby, you may find our HIV and pregnancy guide helpful:


  8. pulane

    Hi, I’m HIV positive. I’ve been on treatment for a year. My husband doesn’t want to go and test, and he doesn’t want to use condoms. What is going to happen to my viral load and my CD4 count? What is going to happen to him? He wants us to have a baby.

  9. Simon Collins

    Hi Edward

    If you are not on treatment, then you are likely to have a much higher viral load. This means that if your partner is also HIV positive, there would be a higher risk of reinfecting your partner.

    However, unless you have drug resistance, whether or not your partner becomes reinfected may not make very much difference to long term health.

    Exercise is really good for your own health. It doesn’t have any effect on the risk of transmission or reinfection. This is all related to viral load levels, whether there is drug resistance and perhaps if there are other STIs.

  10. Edward

    What happens if you have HIV but you are not on treatment and you exercise often and you are fit?


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