Greeting !! I asked a question about a body to body message exposure , I tested negative for HIV after 79 days and after 4 months , I will test for syphilis soon but here in my country there is no penicillin shots only oral doxycycline, are they effective ? Even for latent Syphilis if taken for 28 days? Or should I travel to take penicillin shot in another country, thank u .

Welcome to the Forum.  I’ll be glad to comment.  The exposure that you describe was virtually no risk for any STI, including syphilis.  I anticipate that your syphilis test will be negative.  If you have syphilis however doxycycline would be highly effective for treatment as long as you take it as directed.  EWH ---

Thank you for the quick reply, I am concerned about Syphilis because I had a pimple on my pubic area which disappeared in two days , I think this was a chancre !! My last question : I have read that doxycycline is not effective in treating late latent Syphilis ! Is this true ?

A syphilis lesion would not disappear in just two days.  If the pimple was in the region of your pubic hair (whether you shave your pubic area or not) it may have been folliculitis, a common, non-STI skin condition that typically goes away quickly without specific treatment.---

My final follow up questions before closing this thread , how long a chancre lasts without treatment ? And is it true that chancres usually appear on the penis and rarely on the pubic area ? ….if I test positive does it mean I can’t donate blood forever because the test will always be positive ?

Typically syphilis chancres last a week or more before gradually healing.  Almost 90% of chancres occur on the penis with the remainder occurring on other parts of the body.  A chancre in the pubic region is rare (I do not think I've even seen one in a male).---