Question
Is PEP effective if taken 48 hours after exposure?
2 July 2021. Related: All topics, PEP/PEPSE.
I paid for sex with a woman but the condom tore and I only realised after I was done. There is a high chance that she was HIV positive. I started PEP after 48 hours.
I got a PCR test done 17 days after exposure. It had a less than 20/ml (undetectable) result.
Now between 14 and 35 days after exposure I have had signs of thrush, mild red rash on my face and a couple elsewhere. But no fever or swollen lymph glands.
Can the rash and thrush be because of utter stress and obsession?
My doctor says that the PCR can be relied upon and that I am negative.
Can the PEP have reduced the viral load to less than 20/ml as I took it for 15 days before the PCR test?
Please give your expert advice. I am very anxious. Thank you.
Answer
Thank you for your question.
The risk of HIV from one broken condom is very low. If your partner had an undetectable viral load on treatment, then the risk would be zero. If they were not on treatment the risk might still be only 1 in 300 or lower.
You cannot guess someones HIV status so your assumptions might also be wrong.
You started PEP within 48 hours, so it is likely it will work.
PEP – stands for Post-Exposure Prophylaxis. It is a term used for taking HIV drugs to reduce the risk of infection. PEP usually involves taking a combination of three HIV drugs for one month. The earlier PEP is started, the more likely it will work. Ideally, this should be within a couple of hours. If this is not possible, then still the earlier the better.
Some guidelines include a two-day window to do this (i.e. within 48 hours). After this, effectiveness is much less likely. Other guidelines allow up to 3 days (i.e. within 72 hours). Sometimes this may be more for psychological benefit. For example, if someone is very stressed or traumatised.
No guidelines recommend starting PEP after 72 hours.
After finishing PEP you need to wait a 4-6 weeks before testing.
If the PEP has worked, or the person was not initially infected, this will show as a negative HIV test. The test you did 17 days after the exposure will not be accurate yet.
If the PEP has not worked, this will be shown in a positive test result. Testing 4 weeks after PEP will detect 95% of infections. Testing after six weeks will detect more than 99% of infections. This result doesn’t need to be tested again.
If PEP has not worked, serosonversion usually occurs 1-3 weeks after PEP is finished. However, only 80% of people show symptoms.
Please test 6 weeks after you finished PEP is finished. If you test any earlier, you need to take a second test 3 months later.
Viral load (PRC) tests are not approved to test for HIV. In some cases they can have a role.
Please see a doctor to talk about your symptoms he best way to confirm what is causing them is to see your doctor. He/she will be able to diagnose and treat the symptoms accordingly.
Note: This answer was last updated in July 2021 from an original post from December 2011.
Hi JD, even though he has an unsuppressed viral load, this still remains relatively low in comparison to many finding out they are positive. In your case this is considered a low risk exposure – in the UK you would not be recommended to take PEP.
As your first exposure used a condom there is no risk of transmission. As for the second, oral sex carries little to no risk of transmission. This is because saliva contains anti-viral properties which inhibits HIV transmission in this way.
Please follow this link for more information about testing and transmission: https://i-base.info/qa/factsheets/hiv-transmission-and-testing
Hello
On 17th October 2022 I had receptive anal sex ( I was the bottom ) with a guy and used condom for Anal sex ( confirmed condom was intact as I saw the semen on the tip and it was tied and disposed off in the bin ). I performed unprotected oral sex also without ejaculation , later on 18th october 2022 I asked him to get tested , in the evening of 18th he told me that his sample has to be resent due to doubt , I got a panic attack and spoke to my doctor friend , I started PEP On 19th morning at around 2.00 am and having viropil (TLD )from emcure, PEP was started within 40 hrs of exposure ! Later have found out that he is hiv positive with viral load 62000 copies/ml , I am having anxiety panic attacks sweats , can you please advise what will be my risk with this exposure assuming he has high viral load too ! I am very stressed out !!
Hi Janak, PrEP will not work if you take it after exposure. Instead of PrEP you can use PEP. PEP is a course of daily medication that usually lasts for 28 days. PEP is effective if it is started within 72 hours of the exposure: https://i-base.info/guides/testing/pep-and-pepse
I had unprotected but I forgot to take prep can I take it after or within 24 hours?
Hi Kuteesa, you do not need to do anything. As you have been taking PEP, it will have acted like PrEP. This means while you are taking PrEP you are protected against further potential exposures. You can finish your course of PEP when initially intended.
Hello madam/Sir what should I do when am taking pep for a3rd day and I get another exposure?
Hi Jason, as you started PEP within 72 hours it will be effective. How is your partner doing? Smoking weed will not effect how effective PEP is. While you are taking PEP it is not advised to have unprotected sex as you are unsure of your own status – you could be putting your wife at risk. If your wife takes PrEP (https://i-base.info/guides/prep) or if you decide to use a condom there will be no risk.
Please follow this link for more information about testing and transmission: https://i-base.info/qa/factsheets/hiv-transmission-and-testing
Good afternoon doctor I was exposed to HIV after having sex with a female who denied knowing she was HIV positive but within the same hour I rushed her and I to a near by clinic to run a test and she was confirmed positive and I was still negative I was advices to get PEP in which I took within the next 3-4 hours after exposure. This is my third dose after exposure. I am worried that my immune because I smoke weed but through out my medication I haven’t smoked and I take vitamin C to help boost. How effective can it be. And can I still have protected sex with my wife and it wouldn’t have a side effect. Please kindly advice so I help my self.
Hi Everyone,
I’m a male. I had insertive sex with a female sex worker with unknown HiV status. In between I realised the condom broke and changed it instantly. My worry is, I don’t know when did the condom broke and for how long I was condom less. Though I noticed the broken condom after 5-6 mins of commencing insertive sex. I panicked, and started my pep regimen(245mg tenofovir, 300mg lamivudine and 50mg dolutegravir) between the 31st and 33rd hour after exposure. To be safe, I assumed she was positive. The question is, will PEP be effective when taken after 30+ hours of exposure ? It’s my 16th day on PEP and I plan to finish the 30 days regimen.
Hi Jon, PEP will be effective if started within 72 hours – you are well within this time limit. Do you have reason to think this sex worker is HIV positive? and even so they would be likely to be on treatment which would prevent transmission. Please follow this link for more information: https://i-base.info/qa/factsheets/hiv-transmission-and-testing