How would methamphetamine show up in a urine test when you don't use drugs please explain

Urine : Urine drug tests are typically very accurate. There is always a chance, though rare, that there is a mix up of samples, or that someone gave a patient something that they didn't know about, for example in a drink.

Prob screening test: Many chemicals, including common cold remedies like sudafed, afrin and neosynephrine (phenylephrine) can show up as a positive amphetamine test on the initial screen. However, confirmatory tests (which are way more sophisticated and expensive) can tell the difference. Same is true with methamphetamine. You need to make sure there was a confirmatory test and chain-of-custody of the specimen.