Hi,after an unprotected intercourse i took 1 weeks course of doxycycline 48hours after.would this be enough to prevent syphilis and chlamydia?person is not known to have either or any sti but heard it could he a good preventative? thank u?

This would be 100% protective, but you took more doxycycline than necessary. A single dose of 200 mg within 3 days of sexual exposure reliably protects against chlamydia and syphilis, and is around 60% effective in preventing gonorrhea. This kind of post-exposure prophylaxis is called doxy-PEP and is now recommended for MSM at high risk. However, it is not advised after heterosexual exposures.