is it too soon

  Hello there!
  I am taking the antibiotic called Zithromax and had been taking it for a full week when I had sex
  with my husband. I am also currently on Tri-Levelen, but I have heard that antibiotics take away the efficacy of the birth
  control pill.  Is it very likely that I could be pregnant?  It's only been a week and a half since. Is it too soon to
  take a pregnancy test, either urine or blood?
  I am a little worried about this.  Please write back!
  (and does it depend on the antibiotic or do all of them affect birth control
  the same way?)
  thanks for your help!

[hfhsmdrcs]

_
Dear Katy:
Most antibiotics do not interfere with the effectiveness of birth control pills. Zithromax is not a member of the anti-tuberculous or anti-fungal drugs which are known to increase the breakdown of the pills. Hence, it is unlikely that the TriLevlen would be any less effective on Zithromax.
A urine pregnancy test is reliable 3 days beyond the missed menstrual flow, or 17 days from ovulation. The rules break down in a birth control pill cycle because you cannot know when you ovulated. Thus, the best you can do is test when you have finished the last active pill plus 3 days and if you do not start a menstrual flow by the end of the placebo pills (the last week of different colored pills), see your physician for a blood pregnancy test before starting a new pill package.
Keywords: antibiotics, birth control pills
This information is provided for education purposes only and is not a medical consultation.If you have specific questions, please speak with your physician.