I had unprotected vaginal and oral sex with a older female mid 40s I met in a bar this is my only recent encounter I have had with anybody in a couple of years. This happened mid may 2023.  Now I feel like I am having symptoms, including a small pimple like rash under my arms to the left of my bicep non itchy. I have also been experiencing bad acid reflux that I never had before. Also I feel light headed at times.. these symptoms happened about 5months post exposure. 

My questions.

1. Are any of these symptoms related to hiv 5 to 6 months post exposure?

2. What are my odds of catching hiv with this 1 night exposure?

3. I've read some of the other posts, that say testing is not recommended after just 1 sexual encounter. Is this true?

The main reason I am concerned is because I have read on the internet that rashes in adults are often caused by hiv

You really needn't worry. You had a very low risk exposure in regard to HIV, and also for other STDs. The overall frequency of STDs and HIV is very low in women over age 40, even among those quite sexually active with multiple partners. Second, even if she had HIV, your risk was very low:  the standard estimate is that when a female partner has HIV, the average transmission risk for a single episode of unprotected vaginal sex is one chance in 2,500; the risk is zero for oral sex. If we assume even a fairly high 1% chance your partner has HIV, the chance you now have it would be around one chance in 250,000, i.e. zero for all practical purposes.

Those comments answer question 2.

Question 1:  None of these symptoms is suggestive of an HIV infection. While it is true that skin rash is one of the common symptoms of acute retroviral syndrome (ARS, i.e. initial HIV infection), that rash is nothing like you describe; and there are hundreds of skin conditions that are far more common than ARS rash. I am confident that neither your rash nor other symptoms has anyhing to do with the sexual exposure on your mind.

Question 3: Testing for HIV is a personal decision as much as a medical one. From a medical/risk perspective, I would not recommend you be tested for HIV. However, it also is true that many persons are more reassured by negative lab test results than by professional advice, no matter how expert. (We don't take it personally!). So if a negative test would help you would sleep better and stop worrying, by all means have an HIV blood test. You definitely can expect a negative result.

I hope these comments are helpful. Let me know if anything isn't clear.

HHH, MD

Can I ask some follow up questions?

1. How are these figures 1/2500 exposures ect. calculated? Is it based on science or statistics?

2. Why are heterosexual men less likely to be infected than other groups, is it biology or just luck?

3. In all your experience and expertise, have you or any of your colleagues had a patient who's was infected after 1 exposure?

4. Does me being uncircumcised make any difference in odds of infection?

5. When and where do HIV rashes appear and what do they normally look like. Is it 6 months after infection a year or more. Also would they come and go or be reccurent?

6. In my situation, (unprotected sex with the women) in your opinion can I just move on and have unprotected sex with a regular partner?

2. It's biology and the anatomy of sex. The exposed male genital tissues are small in size and area, compared with infected semen being injected into a partner's vagina or rectum.

3. I am personally unaware of any patient who acquired HIV after a particular exposure they were concerned about, at least not in heterosexual men. This has happened from time to time following anal sex among men.

4. Being uncircumcised roughtly doubles the risk of HIV if exposed -- at least in males in Africa. No data have confirmed this in industrialized countries. But even if the risk is doubled, it doesn't mean much. For the calcuation if my first reply above, double risk makes your chance of having HIV one in 125,000 instead of 250,000 -- which still is zero for all practical purposes.

5. The rash of acute HIV occurs only in the first 2-3 weeks; never is the only symptom; is body wide; and generally doesn't itch and does not come and go.

6. For all these reasons, from a medical/risk standpoint, you do not need testing for HIV. However, many persons -- probably including you -- are more reassured by negative test results than by professional opinion, no matter how expert. Therefore, I believe you should be tested -- not because there is signficiant risk, but because you'll probably keep wondering and worrying about it until you have the negative test result.

Threads are closed after two follow-up comments and replies. So if you decide to be tested, I suggest no further discussion unless and until you would like to return to let me know the result. In the meantime, don't be worried. In the nearly 20 years of this and our preceding forum, with thousands of questions from persons worried about a potentially risky exposure, not one has yet reported they tested positive for HIV. Given the minimal risk of your event and your non-signfiicant symptoms, there is no chance you'll be the first!

I believe the statistics and your expertise. I have decided against testing. I truly believe the rash and lightheadedness I have been experiencing probly have something to do wit lh anxiety, since I have experienced both in the past.