Q and A


Does undetectable mean that someone is not infectious?

My boyfriend has HIV but he says he says he is undetectable.

Is it okay to have sex without a condom or do we need to use them?


Yes, having an undetectable viral load when on HIV treatment (ART) reduces the risk of transmission to zero.

However, this is separate to your second question about what you and your boyfriend decide.

i-Base provide information for people to then make their own choices and decisions.

So the decision on whether or not to use condoms is up to you. You should not feel pressured as you need to be happy with the choice you make.

The PARTNER study provides perhaps the most significant evidence that the risk is zero. This study included more that 900 couples where one partner was positive and the other was negative. These couples were not using condoms.

After more than 58,000 times that couples had sex without using condoms, there were ZERO HIV transmissions. The PARTNER 2 study reported the same results after gay male couples had sex more than 77,000 times without condoms.

The HIV positive person had an undetectable viral load to be included in these results – but this could be for only one month rather than six months. This link has more information on the PARTNER results

A more detailed explanation on viral load and the risk of transmission is in this section of the i-Base guide on HIV transmission.

This answer was last updated in May 2021 from a question first posted on 26 January 2012.


  1. Lisa Thorley

    Hi Anda,

    Weight loss, though now rare can be a side effect of ARVs. What is it that you’re taking? How much weight have you lost?

  2. Anda

    I have been taking my meds for 2 month now but my weight continues to drop down. What can be the problem?

  3. Simon Collins

    Hi Mark – thanks for your comment.

    The i-Base website now has several thousand online Q&A’s and all answers have a caution on the published date. You were commenting on an answer from before the final PARTNER data were published, and the answer has been slightly revised to include this.

    i-Base have been pretty clear on the dramatic impact that having an undetectable viral load has on the risk of transmission. The Q&A on the PARTNER study used a pretty clear graphic to emphasise the results:

  4. Mark

    Further research and a consensus statement from dozens of health experts has shown that people with HIV who are on treatment and are undetectable are not transmitting the virus to their partners. We should say this, loudly and clearly. For more: http://marksking.com/my-fabulous-disease/five-reasons-hiv-undetectable-must-equal-untransmittable/