The unfortunate truth about this stuff
[QUOTE=Gemini10;7235799]Herpes not transferred unless the person having a out break you can she the warts, if you see that mess and still engage its on you.[/QUOTE]Herpes can still be transmitted, even if you don't see an outbreak. It's a virus and goes through what's called a viral shedding phase which is completely invisible. During viral shedding, it can be transmitted which is how a lot of people probably catch it. Without getting too scientific, I'll let you look it up for yourself.
Doxycycline will not prevent STDs. It will clear some of them up though but just like all antibiotics, you can build a resistance to it at which point it essentially stops working. It's a strong one too so if you have a real emergency and it's the one drug that usually works for a bad infection, it may fail you if you have built a resistance to it. It also only works on some bacterial STDs but it will do nothing for you if you catch a viral STD like herpes, warts, HIV, etc.