Can Pseudoephedrine give false positive for amphetamines?

Yes. All variations of methamphetamine, amphetamine, methcathinone and ephedrine have very similar molecular structures, and they all break down to the same compound in your body. In fact, ephedrine is a necessary precursor in synthesizing the other three drugs.

Urine tests, especially portable on-the-spot ones, are designed to detect this compound that these drugs break down into, not the drugs themselves, so whether you are on methamphetamine, amphetamine, methcathinone, or ephedrine or even pseudo ephedrine, you can test positive for amphetamines.

If you do test positive and you know you were only on ephedrine or pseudoephedrine, you can request a re-test that involves a proper lab using blood or hair samples