Hello doctors,

I’m conscious of your hesitancy about anxiety-driven questions, especially repeats by existing users. This will be the last. 16 days after an unprotected oral encounter, I wanted to get your thoughts as to whether the below risk analysis is correct:

- NGU: Unlikely. No symptoms within 16 days.

- Chlamydia: Unlikely. Negative test 2 days after encounter. No symptoms within 16 days.

- Gonorrhoea: Unlikely. Negative test 2 days after encounter. No symptoms within 16 days.

- HSV 1: Unknown. Sores not noticed at the time, but lighting was dim. No symptoms.

- HIV: Very unlikely / impossible. Not transmitted via oral exposure.

- Syphilis: Unknown. No symptoms within 16 days.

- Crabs: Very unlikely / impossible. Not transmitted orally. No symptoms within 16 days.

Would you recommend any other course of action? I’m yet to take a HIV blood test (UK STI clinic). Would taking one 3 weeks after an encounter yield any reliable results?

Thank you.

To your current questions:

NGU: Not only unlikely, but probably not important. NGU from oral sex is likely to be harmless and to clear promptly on its own, without treatment, and unlikely to harm partners. Many (most?) cases are believed to occur because the urethra is not used to exposure to normal oral bacteria, but those bacteria probably are harmless.

Chlamydia:  Very rarely if ever transmitted oral to penis, and the negative test further confirms no infection.

Gonorrhea: Almost always causes obvious symptoms, so lack of discharge and painful urination are strong evidence against it. And so is the negative test.

HSV1: Unlikely if partner didn't have an overt cold sore, and also unlikely in absence of symptoms. There is also a 50:50 chance you are immune due to past HSV1 infection (with or without recognized oral herpes).

HIV: Just as you say. I wouldn't recommend testing at all. But if you go ahead with that when home, I agree an NHS GUM clinic would be an excellent choice for expert care; or a private sexual health clinic like London's Freedom Health. But I would suggest waiting to the 4-6 week mark, when the 4th gen tests are conclusive. A negative result at 3 weeks would be around 90-95% conclusive. But since the chance you caught HIV probably is under 1 in 100,000, I really see no need.

Syphilis:  Very rare in heterosexuals in western/industrialized countries, including Spain (to the best of my knowledge). But absence of symptoms is less secure at 16 days than for most other STDs. It can take up to 3 weeks, maybe sometimes as long as 4 weeks, for initial symptoms (the chancre, a penile ulcer) to appear. But the chance is sufficiently low that you really needn't worry (and if I were in your situation, I would already have resumed unprotected sex with my wife without worry).

Crab lice:  There are no data whatever on risk from any single exposure. But I would think lice and itching would have shown up by now.

I hope these comments are helpful. Do your best to stop all worry about this. Don't confuse your guilt or shame over a sexual decision you regret with STI risk from that decision. They aren't the same. Deal with the former as you need to, but you can disregard the latter.

HHH, MD