Hi i recently had an encounter and I asked a question regarding Syphillis and gonorrhea. Dr hook explained that I was no risk through this exposure. Day 9 after this exposure whilst taking doxycycline for 7 days I developed a red mark on the underside of my penis close to my scrotum About 4 mm in size. This mark devoleped and on very close inspection looked like an ulcer. This thing has now been there for 15 days, it looks now like a pinkish type of scar and doesn’t seem to be getting better at all. I took valtrex for 5 days as I know I suffer with herpes however this hasn’t touched it. Dr hook said that Syphillis was not a concern due to the antibiotics I took and am still taking. I can’t get the fact that perhaps I did catch Syphillis and the doxycycline isn’t working. I’ve been taking them for 3 full weeks now. Would it be possible to develop a Syphillis chancre whilst on day 9 of doxy ? I have a partner and am terrified of passing something on to her. 

Welcome back. I will be responding this time, but I reviewed your recent discussion with Dr. Hook. I agree with all he said. If you understood and believed his advice, you really should not have needed to ask these additional questions. Truly, you should not be at all worried! Here is why:---
---
---

Thank you so much for your swift response. This is very reassuring, just a couple more things, when I started the doxy I was drinking a little bit of milk in the mornings then 15mins  later I was taking the doxy, if say I did contract Syphillis would this of made the doxy less effective? I’m really trying to let this go and thinking of going for a test,just to put my mind at rest, how long after the doxy if I stop today  could I test? 

Taking doxycycline at the same time a large amount of dairy food (like a large serving of ice cream) would reduce its absorption, but a small amount would have no effect. I any case, you've now had 3 weeks of treatment. ---

Thank you it’s very reassuring, this red mark has turned into a tiny crater type appearance? Which looks more pronounced under a light, that worry’s me. But just to clarify it’s impossible that this is Syphillis after all the antibiotics I have taken? There’s no way they could have failed even if say I was infected? I am going to go for a test just to put my mind at rest would testing a week after taking my last doxy be reliable if say I were infected? 

It's not an STD problem, period. As any minor skin injury heals, it can go through changes in appearance like you describe; this says nothing about the cause. Yes, syphilis is impossible; even if you were infected at the time, it now is gone forever, no test will ever be positive, and it is not transmissible to anyone sexually or by any other kind of exposure. There has never been a case of syphilis that was not cured by doxycycline in the dose and duration you took it. Testing for syphilis will be a waste of money and time, but if you're going to do it despite all scientific rationale, I would suggest waiting until at least 3-4 weeks after completing doxycycline.---