syphilis antibiotics question

[Regretful1]

Hi Doctors,

I made a bonehead mistake and may have taken an extra dose of my 100mg Doxycycline treatment.  To be more specific, on day 10 of the 14 days I'm scheduled to be taking the antibiotic I may have taken 3 pills instead of two.  I also mistakenly missed one dose on day 5 of the treatment but was advised not to take a "make-up" dose for that by my doctor friend who proscribed the treatment (he's currently out of the country which is why I'm writing now).

I looked online and most drug websites said that an extra dose may make side effects more likely, but I'm curious to know if one extra dose in the two week treatment has any chance of making the treatment less effective.

Thanks very much.

[Edward W Hook, MD]

You have nothing to worry about.  The half life of doxycycline is such that having taken the extra dose now and therefore being one dose short at the end of therapy will not in any way effect the outcome of your therapy.  In addition, there is little risk to you of having bad side effects from a single extra pill other than perhaps a little higher chance of having an upset stomach.  If that hasn’t happened yet, you have nothing to worry about.  The chances of other side effects (rash, etc) are negligible.  Hope this helps.   EWH

[Regretful1]

Thanks for clearing that up.  I was less concerned about side effects then I was with the effectiveness of the treatment, but your reply seems to indicate that's not a danger.

Also, although I'm sure you'll say it's unnecessary I'd like to test to make sure I'm STD free.  My understanding is that if I wait about a week after I've finished the doxy it would not effect any blood or urine tests.  Am I correct in that thinking?

BTW - let me add my voice to the chorus of thanks for this service.  It's absolutely invaluable.

[Edward W Hook, MD]

You are correct.  After  a week urine and blood tests will not be effected (in fact, the blood tests wil not be affected at any time).  EWH