Pyridium and substances with like property show color reaction in urine with low pH and these possibly result in a false positive in Bilirubin test strip.  This is a unique reaction to the strip test method and also it is a common problem to all the other strip tests.  This problem is an on-going research project and it is still in the process of further development.  So if this kind of problem occurs, then the decision has to be made upon consideration of other clinical diagnoses and requires confirmative (e.g. Rosin method) measurement result.