I had a “benefit friend” that I occasionally give bjs to, I am female -he is male. We have not engaged in genital sex… what are my realistic probabilities that he could give me a STi from the bjs. I ask because I recently started a relationship… the last time I gave my benefit friend a bj was 2 weeks before I started a relationship which started with a bj…in my new relationship we have also had oral sex but no genital sex. 

Side note since I started talking to the new guy ( and before we did anything ) I had a stash of azithromycin so  one week after my friend with benefit bj I took a gram of azithromycin, but puked a ton ( like my whole dinner) about 30 mins after I took it- so the next day I took 500mg more… would that cure any sti in my throat if I got it? … we are gonna get tested before we have genital sex, I just wanted to make sure he wouldn’t have gotten any sti from my bj before we test genitally.   Second side note… I haven’t have genital sex in years

Also if a guy had any type of Sti like chlamydia gonorrhea or syphillis woould he eventually show symptoms? My benefit friend doesn’t have any symptoms that I know of

Oral sex in general is pretty safe in regard to STIs, with essentially zero risk for some (including HIV, chlamydia, trichomonas, and others); and much lower risk that vaginal or anal sex for most others. Receptive fellatio -- i.e. performing oral sex (BJs) on male partners is modestly risky, however. And assuming your benefit friend is not otherwise at high risk (multiple partners, sex with other men) -- and if he had no symptoms of genital infection (discharge, penile sores, etc) -- then the chance you were exposed to an active, transmissible STI is quite low. Finally, while I would not have recommended self treatment with azithromycin, it probably reduced the possibility you had oral gonorrhea, chlamydia, or syphilis. Vomiting soon after taking it might not have made as much difference as you feared:  but after 30 minutes, most of it had been absorbed. (There was research on this ~30 years ago, when azithromycin was new; it remained effective against chlamydia if vomiting occurred at least 30 minutes after taking it.)

There is little chance you have any oral STI and hence very low likelihood of transmission to your new partner by oral sex. For reassurance, you could have an oral swab test for gonorrhea and chlamydia. (Chlamydia rarely infects the throat and almost never is transmitted by oral sex, but chlamydia testing is automatically done along with gonorrhea.) You also could have blood tests for HIV and syphilis. Alternatively, speak with your former benefits buddy and ask him to have urine testing for gonorrhea/chlamydia and blood tests for HIV and syphilis. If negative, you'll know you could not have been infected.

As for your last question, most men -- but not all -- would have obvious symptoms if they had acquired gonorrhea, chlamydia, or syphilis. 

All things considered, you really shouldn't be concerned at all; there is almost no chance you have any STI or that your new partner is at risk.

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

HHH, MD

I’m glad and surprised you state that most males exhibit penile symptoms, looking at online sites such as cdc and std check state that only 10% of men show signs for chlamydia and 50% show signs for gonorrhea? 

Do you know the infection rate for transmitting oral stds? 

I'm pretty sure you misunderstood something you found online. No reputable STD professional resource believes only 10% and 50% of men with urethral chlamydia or gonorrhea, respectively, have symptoms or signs of infection. Those figures would be about right for rectal infection:  are you sure you were reading about the urethra? (I know what I'm talking about when it comes to male symptoms, especially for gonorrhea. At least 95% (usually 98-99%) of men with urethral gonorrhea have very obvious symptoms, and it's probably around 60-70% for chlamydia. Here is a link to the first and still main research study on asymptomatic gonorrhea in men; note the authors. It was many years ago, but I have kept up with the topic. https://pubmed.ncbi.nlm.nih.gov/4202519/  

As noted above, chlamydia rarely infects the oral cavity, and when it does, it usually clears up spontaneously within 2 weeks. There has actually never been a scientifically well documented case of chlamydia transfer from oral to penis. When oral gonorrhea is present, it probably is transmitted by oral sex (i.e. to a partner's penis) roughly 10% of the time.

I think the internet is not your friend in this situation. As for many anxious persons who search online about a the topic they're worried about, you're seeing mostly information that enhances your fears and missing the reassuring bits, or misunderstanding what you find (as implied by your mistaken 10% and 50% figures). Don't overthink this. There is nearly zero chance you have any STI from your benefit buddy exposures.

Thanks for the thanks. I'm glad to have helped. Take care and stay safe.