[Question #5311] Doxy Question for Syphilis Treatment

24 months ago
Hello Doctors.
I was recently prescribed Doxcycline Hyclate (150mg twice daily for 14 days) by my doctor for suspected syphilis. Long story short, I had an unprotected exposure with a csw about 2.5 months ago. A few weeks later I had a sore appear on my penis. My doc thought it was likely syphilis but he wasn't sure. Blood tests at the time - while the sore was present - were negative, as was one a few weeks later. However, when I saw my doc again recently he felt swollen nodes in my groin (the reason for my visit to him) and he decided to prescribe my the doxy to be cautious. I have a couple of questions about all of this that I hope you can help with:
First, if this is syphilis, how effective will the 150mg of doxy be twice daily for 2 weeks? I know that it's an alternative treatment to the penicilin but it also seems like it's used fairly commonly. Does the fact that I'd be starting coming up on three months from the exposure have any bearing on the efficacy? I've had no symptoms other than the initial sore and lymph node swelling.
Second, I've read that with the penicillin injections there's a JH reaction that essentially confirms the infection (i.e. if you didn't have syphilis you won't get the reaction because it results from the bacteria dying off). Does that same reaction occur with the doxy? Just want to know if I should be prepared for that. Any other reactions or side-effects I should be prepared for?
Third, my doctor said to take the doxy WITH food and water to avoid stomach upset, but multiple sources online say to take on an EMPTY stomach for the same reason. Who's right?
Fourth, the CDC guidelines talk about 100mg x2 daily, whereas my doc prescribed 150mg x2 daily. Is this okay?
Thank you for your help.
Edward W. Hook M.D.
Edward W. Hook M.D.
24 months ago
Welcome to the Forum.  I'll be glad to comment. As I read your post however, I wonder if the lesion on your penis was in fact syphilis and, even if it was, whether your lymph nodes swelling is related or not.  To help me, could you tell me how long the sore had been present before your first blood test, as well as whether the sore is still present and, if not, how long it was present before it went away.  In addition, can you tell me about your sexual partners -same sex or opposite (the reason I ask is the currently about 80% of all syphilis in the U.S. occurs in men and primarily men who have other men as sex partners.  

Let me now address the questions you asked:
1.  as you point out, 150 mg of doxycycline is 50% more than the recommended dose of drug.  The drug is highly effective in persons who take all of their medicine.  It is used relatively widely.

2.  Precisely how often the JH reaction occurs in persons with syphilis is not clear -probably in between 30-50% of infected persons.  It can occur as well in persons treated with doxycycline but the absence of a JH reaction does not mean that a person did not have syphilis.  hen it occurs, it occurs within 12-18 hours of beginning to take treatment and lasts less than 24 hours.  

3.  Most people would suggest and empty stomach is better than with food but one of the side effects is to give a person an upset stomach.  Milk and mild products are probably to be avoided if you are going to take you medicine with food.

4.  As you point out 150 mg twice daily is more than is typically recommended.  Taking 150 mg will not harm you but if you are a normal sized person 100 mg twice daily should be sufficient.

I hope this information is helpful.  EWH
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24 months ago
Thank you for your comments, Dr. Hook. Very helpful. I'll try to address your questions: 

At the time of my first blood test, the sore had been present for 3-4 days, starting approximately 4 weeks from the exposure. The sore took about 2 weeks to resolve at most (probably slightly less if anything). And my second blood test was about 2 weeks after it resolved (so about 8 weeks from exposure). These were RPR screening tests according to my doctor's office. I felt swollen lymph nodes while the sore was present and for a couple of weeks after and like I said in my initial post, my doctor noted them recently when he prescribed the doxy.

My partner for the exposure in question was female. She performed unprotected oral sex on me and then protected vaginal sex, though the condom slipped pretty low so I'm not sure exactly how protected it was the whole time. When my sore appeared I asked her about her status and she said she tested negative for all STDs back in December, but she's acting pretty shady about testing (she showed me her result from December, so I know that's legit. But she claims that she gets tested every ten days, which seems highly unlikely to me, especially because she doesn't have anything to prove any tests since Dec, so she could have gotten something since that test.)

I hope that's helpful. Let me know if you need any other details. I just wanted to follow up on a couple of your prior responses too:
1- would the course of 150mg x2 daily for 2 weeks would be sufficient to cure a syphilis infection of almost 3 months duration?
2- understanding that a JH reaction does not always occur in persons with syphilis, I assume the presence of such a reaction would be highly indicative of an infection? 
3- what distinguishes a JH reaction from a "normal" adverse reaction to the doxy?
4- if it is syphilis, how much time on doxy is required to render oneself non-infectious? (I'm not planning on any sexual activity, just curious since I think the penicillin shots render you non-infectious within just a few days)

Thank you.

Edward W. Hook M.D.
Edward W. Hook M.D.
24 months ago
Thanks for the additional information.  The additional information makes it exceedingly unlikely that the sore was syphilis. When you combine: low syphilis rates in women; very low likelihood of syphilis transmission through oral sex or (mostly) condom protected vaginal sex; her negative blood test in December (like you, I find it unlikely she is tested every 10 days) ; and your negative 2nd test more than 4 weeks after the lesion appeared I can virtually assure you that this was not syphilis.  What it might have been I cannot say and I'm glad to hear it is better. Regarding your follow-up questions:
1.  Absolutely.  Be confident that the therapy you took would cure syphilis.
2.  Yes, a J-H reaction would be highly supportive of a syphilis diagnosis. It sounds like you did not have one however, did you.
3.  A J-H reaction lasts starts within 12 hours of therapy and lests less than 24 hours.  It is a flu-like illness. There are a great many different possible reactions to doxycycline but they would not mimic a J-H reaction.
4.  Doxy therapy would render the infection non-infections after a few days of treatment, even before the entire course was completed.  

Hope this helps.  EWH
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24 months ago
Very helpful, thank you Dr. Hook.

I wanted to make a clarification: I have not yet completed the course of doxy. I started the doxy the day after I started this thread, so I'm currently three days in (I've taken seven 150mg tablets, one in the morning and one in the evening for 3.5 days). I am three months from the exposure in question, and I plan to adhere closely to my course of doxy for the next two weeks. With those facts clarified I have just a few final questions:

1- I have not encountered any "flu-like" symptoms/rigors/chills etc., so I assume I'm in the clear regarding a J-H reaction at almost 4 days into treatment?
2- Prior to starting the doxy I was still getting daily pain from the swollen lymph nodes in my groin. This stopped within 36 hrs or so of starting the doxy. Is that potentially supportive of a syphilis diagnosis?
3- If it is potentially supportive of a syphilis diagnosis, I assume the lymph nodes no-longer swelling is supportive of the doxy working effectively against the disease?
4- Is it common for lymph nodes to stop swelling so fast (i.e. within less than 2 days) after initiating treatment?
5- In case it wasn't clear from my initial post, I am (today) three months from exposure. Starting doxy treatment this far out from exposure, is it still a reliable form of treatment (assuming I complete my twice daily 150mg course of treatment for two weeks)?
6- Some sources describe a temporary exacerbation of syphilis symptoms after starting treatment. Since I already experienced what could have been a chancre that healed long before I started the doxy, what I could expect to see? Typical rashes etc., or would they only become exacerbated if already present when treatment begins? (I have not experienced any such thing, but am just curious in case anything develops).
7- As I mentioned previously, my second RPR blood test at 8 weeks from exposure and 4 weeks from appearance of lesion was negative. Is it possible for you to estimate the % level of accuracy of that test? How far from exposure (or lesion appearance) would be ~100% conclusive?

Final question unrelated to my specific case (please do not feel obligated to respond): many sources talk about syphilis being transmitted through direct contact with lesions only. What I am confused about is whether skin to skin contact can still transmit the infection even when such lesions are not present. For example if someone had a chancre which resolved, and they had not yet developed secondary lesions, would they be infectious? If lesions are required it would seem like people with early syphilis would go through periods of non-infectiousness, such as before the chancre, between the chancre and the rash etc. I am missing something?

Thank you so much for all of your responses and assistance.
Edward W. Hook M.D.
Edward W. Hook M.D.
24 months ago
Thanks for the additional information.  On to your final follow-up questions (as per Forum Guidelines, we provide up to three responses per question.  this is the 3rd response to these questions.  There will be no further responses to this thread):

1.  Correct.  If you had a J-H reaction it would have occurred by now.  Not experiencing a J-H reaction however does NOT mean that you will not respond to the therapy you are taking.
2.  Yes, resolution of symptoms or signs suggests a response to therapy.  It however does not mean that syphilis is the infection that is being responded to.  Lymph node swelling is a non-specific sign of inflammation and can be the result of many different types of infection.
3.  Repetitive.  See response above
4.  Yes
5.  Understood.  Yes, two weeks of doxycycline is effective for syphilis of three months duration 
6.  Exacerbation of signs or symptoms following beginning therapy is characteristic of the J-H reaction.  You did not experience a J-H reaction
7.  Your negative RPR results are a strong indication that you do not have syphilis.  On rare occasions, the RPR titer is so very high that the test is not positive- this is called a "prozone reaction" and is diagnosed by diluting the serum used for the RPR testing.  A second approach to diagnosis of syphilis is to request a treponemal test which is a different sort of test from the RPR which is a "non-treponemal" test.  Both tests would be highly sensitive (>99%) for syphilis in a person who had syphilis for 4 or certainly 8 weeks.  I remain skeptical that the cause of you lesion and symptoms was syphilis based on the test results you have reported.  

Final question.  Syphilis is transmitted through direct contact with lesions.  No lesions, no transmission through contact.  So yes, when persons do not have lesions, they are non-infections.  During these periods of non-infectiousness, called latent stages, untreated persons with syphilis are not infectious.  

I'm pleased you are responding to therapy, whatever this process might be.  Take care.  EWH
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