I HIGHLY doubt it. That would be insane if it did.
ya bro
Depending on what they are checking for. If they are checking for methamphetamine and you have taken claritin D the amphetamine in the claritin will cause you test positive for amphetamines. ---No...
Librium is a benzodiazepine and therefore, like Xanax and Valium, will show up on most drug test kits (if they test for benzodiazepines.)
Nothing, large amounts is possible to show a false positive for PCP though (unlikely).