All commercially available tests for pregnancy look for the presence of the beta subunit of hCG or human chorionic gonadotropin in the blood or urine. They are usually performed after a missed menstruation or 2-3 weeks after ovulation. (wiki). There is no reason for an antibiotic to cause a false negative when testing for hCG.
You may need to wait longer for the hCG in your system to build up to adequate levels for the testing product to detect hCG in your system.
However,studies clearly show that rifampin decreases the effectiveness of birth control pills in preventing ovulation.
Please use a barrier method of birth control while on this or any other antibiotics.
Answers & Comments
Verified answer
All commercially available tests for pregnancy look for the presence of the beta subunit of hCG or human chorionic gonadotropin in the blood or urine. They are usually performed after a missed menstruation or 2-3 weeks after ovulation. (wiki). There is no reason for an antibiotic to cause a false negative when testing for hCG.
You may need to wait longer for the hCG in your system to build up to adequate levels for the testing product to detect hCG in your system.
However,studies clearly show that rifampin decreases the effectiveness of birth control pills in preventing ovulation.
Please use a barrier method of birth control while on this or any other antibiotics.
I don't "think" so, but I know that if you take BCPs while on rifampin the BCP can fail.
Get another test.
Best wishes