I am a 40 year old married man in the southwest US. On April 24, I went outside of my marriage and had unprotected vaginal intercourse with a woman I didn’t know very well. The intercourse was about 25 seconds to completion. On May 4th, she called and informed me that she just found out that she had Trich and to see her for a prescription of Metronidazole (4 tablets at once). I hadn’t had any symptoms of any STD since, and I know my chances of HIV are small from reading similar responses. How long after completing the treatment can I have sex with my wife again? I’ve definitely learned my lesson and have too much anxiety to repeat an action like this. Thank you in advance.

Let me start by saying that your casual partner did a good thing by letting you know of your exposure and arranging you to be treated for trichomoniasis. No everyone would do that.  Presumptive treatment is the recommended approach. Trichomoniasis can occur in men without symptoms and the spread the sexual partners. I trust that you have not had sex with your wife in the interval between your casual encounter and being informed of your exposure and taking the metronidazole.

With regard to your risk for HIV, statistically the risk is quite low. First, HIV is relatively uncommon amongst heterosexual women who do not use IV drugs. In addition, the risk for transmission of HIV in the unlikely circumstance that your partner had untreated HIV infection is less than one transmission of infection for every more than 1000 sexual encounters (in other words, even if your partner did have HIV, chances of you not acquiring the infection from her are more than 99.9%).

If your partner was diagnosed with trichomoniasis, it is likely that she was tested for other STI’s including HIV. My advice would be for you to ask her for this information. Most people tell the truth when I ask. I anticipate that you will find that she did not have HIV.

I hope this information and perspective helpful to you. If any part of my response is unclear, or there are additional questions, please feel free to use your up to two forks for clarification. EWH

Yes, there should be no need to worry that you might transmit trichamonas now that you have been treated.  EWH 

I spoke with her and she said they gave her a full STD panel, so she never had HIV. Just Trich.

Thanks again for your insight!