Tylenol Sinus Caplets

I recently took a drug test for a job position and it came back inconclusive. I was asked to take another one 2 days later and still am waiting on the results. I have been taking tylenol sinus capsules(red and green ones) occasionly and took some about 24 hrs before the oral swab drug test. Could this possibly be the reason as to why it would be inconclusive?

[Sandra Y, RPh]

Yes it could.  Currently there are more than 250 over-the-counter medications and prescription drugs that can cause false positives. Over-the-counter cold and allergy remedies that contain ephedrine, pseudoephedrine, propylephedrine, phenylephrine or desoxyephedrine would give amphetamine false positives.