Q and A

Question

Can I have sex with someone who is positive and not catch HIV?

16 January 2018. Related: All topics, HIV transmission.

Answer

Answer: Simon Collins

Yes, there are lots of ways to make sure HIV is not transmitted during sex.

  1. One of the easiest and most effective ways is just for the HIV positive partner to be on treatment. An undetectable viral load makes HIV untransmittable. (See: The evidence for U=U).
  2. Another relatively recent option is for the negative partner to use PrEP. This is an oral drug that when taken as prescribed is highly effective. (See: UK guide to PrEP).
  3. You can use condoms which are an effective barrier against HIV (and other STIs). Condoms need to be used carefully, preferably with plenty of lube. (See: How to use a condom (male and female).

HIV is a much less infectious virus than many other sexually transmitted infections (STI’s).

Even without a condom, the risk from a single exposure is less than, for example, 1 in 300. The actual risk becoming infected varies depending on many factors. These include the type of exposure, whether the other person is HIV positive, how high or low their viral load is, the duration and roughness of the sex etc.

If the partner is HIV positive, then viral load is the most important factor. The PARTNER study reported zero HIV transmissions after 900 couples had sex more than 58,000 times WITHOUT condoms. In this study undetectable viral load was defined as being less than 200 copies/mL.
https://i-base.info/qa-on-the-partner-study

Risk factors for penetrative sex without a condom with someone who has a very high viral load could be as high as 1 in 10 (10% risk). But the risk is effectively zero with someone who is taking treatment and who has an undetectable viral load.

This question was updated in January 2018 and November 2016 from an original answer posted in June 2007. i-Base no longer answers individual questions about HIV transmission and risk. (See: Question 1 at this link).

209 comments

  1. kholo •

    I slept with an hiv + lady, I didn’t know she had the infection until after we started not to use protection, then the following week she told me she had been positive for a year and her cd4 count is 480, is ther a chance that I may be negative?

  2. Lisa Thorley •

    Hi Susie,

    If your partner is on treatment and is undetectable then the risk of transmission is close to zero. As the PARTNER study has recently shown. Please see:

    http://i-base.info/htb/30108

    If he is not on treatment, even if he does not ejaculate inside you there is still a risk as the sex is unprotected. If you are worried, condoms are your best bet.

  3. susie •

    I just recently found out my man has the HIV virus. We use unprotected sex but he has never ejaculated in me. What are my risk of catching the virus?

  4. Simon Collins •

    Hi Kimberly, any risk to you is very low, even if you don’t use condoms. See this information to decide this for yourself:
    http://i-base.info/qa-on-the-partner-study

  5. Kimberly •

    My boyfriend is HIV positive and taking the medication daily. He has been doing this for 6 years. I was wanting to know how high the chances of are me contracting it since his load # is low and also his medication working.

  6. Simon Collins •

    Hi Masai, how is your girlfriend doing? This is important for her and this is what the i-Base service is for.
    For your questions, please see the related questions at this link:
    http://i-base.info/qa/what-are-the-most-asked-questions

  7. Masai •

    My girlfriend tested positive while i tested negative should i be worried?
    Note:
    We went for HIV testing after 40 days of unprotected sex.

  8. Simon Collins •

    Hi Des, it is important to have a routine check-up for STIs if you are pregnant. This will answer your questions.

  9. Des •

    Hi should I be worrried about catching an Sti from someone who has one if I used a condom for oral and vaginal it didn’t last very long it was maybe a minute of sex but I didn’t know they had an sti until like 3 months later when my mother mention the person having one I’ have an paranoid mindset I just want to know my risk because I have an baby on the way

  10. Simon Collins •

    Hi Azjz, yes, it is possible to become positive from only having sex once. This is a very low risk though. On average, for a man, the risk might be 1 in 500, even if the woman is HIV positive and they do not use a condom. Please see question 1 at this link:
    http://i-base.info/qa/what-are-the-most-asked-questions