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 Edy,

    Neither ARVs, nor HIV impact a persons ability to have children. If you’re having issues with conceiving, you should talk to a fertility doctor.

  2. Edy

    I’ve been on Arvs for almost 9 years and my viral load is undetectable.how ever I have been trying to make my girlfriend pregnant all invain and she’s getting worried and yet she has a kid with another man.
    Could be problem be with me or my medication and what can I do to make a baby real quick

  3. Roy Trevelion

    Hi Nosiphiwo,

    I’m not sure about the risk of reinfection. There could be a risk of reinfection if your partner has HIV that is resistant to the HIV meds you’re taking.

    But can I ask about the reasons that your partner is not on HIV treatment (ART). The START study showed important benefits of starting ART for people who are HIV positive. And that’s even starting with a high CD4 count.

    If you live in South Africa you can contact the Treatment Action Campaign at this contact link. They can give local support.

    And here is the Introduction to ART. There’s lots of info in this for your partner.

  4. Nosiphiwo

    Good day, my partner is not on medication, i am and we are not using condoms. what are the risk here? i have told him about re-infection and i think i am more at risk because i control virus until sex then reinfection happen.

    Verry worried

  5. Lisa Thorley

    Hi Jordan,

    At the moment your CD4 is low, though in time it will rise, this is what you need to be thinking about. Weight gain is a complex issue, if you’ve lost weight due to being positive, any weight loss should gradually be regained once on meds. You’re on meds, so it will be a question of time. There’s no reason why you can’t be a body builder, this will however need to be through natural means, so no weight gain supplements.

  6. Jordan

    Good day. I’m positive with a cd4 count of 125. I started treatment about a month ago. My concern is, I’m a bodybuilder and would like to know is there any chance I will ever add weight again if I continue using my treatment till my viral load becomes undetectable

  7. Roy Trevelion

    Hi Jae,

    Do you mean are you at risk of reinfection? As Simon explains above, if your partner was HIV positive he would need to have drug resistance to the drugs you’re taking to cause reinfection.

    If you are still undetectable, and as you haven’t seen viral rebound, it seems likely that there’s not reinfection with drug resistance.

    But please see the doctor about your symptoms. They need to be checked out.

  8. Jae

    I’m HIV positive with an undetectable viral load (20). I recently had an encounter with another male. He claimed he was negative, but I don’t know if I can believe him. 3 or 4 weeks later, I followed up with my doctor and had blood tests tan on me. I was still undetectable, but again, that was only 3 o4 weeks after my encounter. Since the encounter, I don’t know if it’s stress or what, but I have a headache and my lymph-node on the light side is sore. Am I at risk?


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