Thank you for everything you do here.

I plan on visiting a relatively high-end CSW in Dubai. I will engage in protected sex, but would like to also explore cunninglingus and rimming, both of which I will be giving unprotected.

1. Hypothetically, if I took 100 mgs of dioxclyine before and after the act, would that provide me with a decent level of protection against any potential STDs from cunninglingus and more importantly, any bacterial infections from rimming?
Referring to this study here: https://pubmed.ncbi.nlm.nih.gov/38118022/

2. Would you consider this a reasonable/effective approach?

You mean doxycycline. Post-exposure prophylaxis with this drug is called doxy-PEP and is a recent innovation in STI prevention -- but not recommended in a situation like yours. It's a bit peculiar that you cite that particular study, which found that doxy-PEP didn't work to prevent heterosexually transmitted STIs in women. You also are considering a dosage that has not been studied; the treatment used in the research you cite and other studies, and the current recommendation of CDC and other public health agencies, is 200 mg in a single dose taken within 72 hours after exposure (ideally within 24 hr). The main studies showing doxy-PEP to be effective against chlamydia and syphilis were done in far higher risk situations than you will be in -- specifically in men having high risk (unprotected anal) sex with other men. One of those studies, done by my own University of Washington colleagues, is this:  https://pubmed.ncbi.nlm.nih.gov/37018493/. All agencies that now recommend doxy-PEP limit that advice to high risk MSM. It may eventually prove to be effective in other settings but probably never will be advised in low risk situations like yours.

There's really no point in doxy-PEP in the situation you describe and I advise against it. You won't be at significant risk for the two STIs that it works to prevent, syphilis and chlamydia. Cunnilingus and analingus will put you at a small but real risk of oral gonorrhea, which is not prevented by doxycycline. Further, like all antibiotics, doxycycline is not effective against the viruses and parasites that are the main causes of gastrointestinal infection from fecal or anal exposure, and has not been studied to prevent gastrointestinal bacterial infections. Might it work against this small risk? Maybe, but no way to know for sure. A possible down side is that if you do become infected, it will be with a more resistant bacteria than otherwise.

Having said all that, congratulations on taking the most important steps to assure your safety:  selection of a likely low risk partner (as most "high end" female escorts are), and using a condom for vaginal sex. But that's all I would recommend. However, assuming you might decide to ignore my advice and proceed as planned, at least take the drug in the way the research supports -- a single dose of 200 mg following the exposure.

I hope these comments are helpful even if not what you were hoping to hear. Let me know if anything isn't clear.

HHH, MD

In light of your response,  if I did want to take an antibiotic to protect myself against potential gastrointestinal infections/oral gonorrhea from cunninglingus/anal exposure, which one would be preferred 'in theory'? 

I still advise you take no antibiotic at all in this situation. Your overall risk is too low.