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Date of last update: 10/14/2017.

Forum Name: Obstetrics

Question: promethazine and false positives

 maglmadi - Tue Mar 08, 2005 10:30 pm

Two weeks ago my kids got the flu. The three of us saw the doctor together. I only had nausea while the kids had the full blown flu. the doctor gave me promethazine 25 mg tablets and said take half a pill every four hours as needed. well in the course of two weeks i have taken five and a half of theses pills, the last one four days ago. i am four days late and decided to take a pregnancy test. i took two, both were positive. i then remembered the information sheet on the promethazine said may cause false negative/positive in a pregnancy test. maybe i never had the flu maybe i was pregnant. my doctor is out of town untill Monday and i can't wait that long. is it possible i am not pregnant because of the promethazine, and would a blood test give an accurate test result. please help[/b][/quote]
 Dr. Anthony Solomon - Thu Mar 10, 2005 6:23 pm

I have checked exhaustively the interactions, cautions, contra-indications and side-effects of this drug and found no evidence that it affects the results of a pregnancy test.

It is one of the safer antihistaminic drugs that can be used in pregnancy. If it is true that it interferes with the results of a pregnancy test, it would be more likely to give a false negative rather than a false positive result. The drug acts for up to 12 hours and traces will therefore not be present in the blood 4 days after discontinuing the drug.

A blood pregancy test is a more accurate test, so you can have that done for confirmation.

I hope this information is helpful.

Dr Anthony Solomon

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