Do not self medicate.
No reason to think you have syphilis, as your risk was very low.
Thank you for your answer. I do not want to self-medicate but if there is a chance that this particular medicine can prevent syphilis, then I could take the risks of possible side effects over the chance of getting infected.
We never give medication info. We never tell someone to self medicate, helps build of a tolerance to medicine thus making things resistant to antibiotics.
True, we don't give medication advice. But trust me on two things: 1) there is no STD you can catch from oral sex that should be treated or that would reliably be prevented with oral penicillin; and 2) oral penicillin definitely should not be used to treat syphilis. I also agree there is no chance you caught syphilis anyway.