Not saying Wikpedia is the fountain of all Medical Knowledge but here's what they say..
Methamphetamine has found use as both a medicinal and recreational drug.
Medical use
Methamphetamine has been approved by the Food and Drug Administration (FDA) in treating ADHD and exogenous obesity (obesity originating from factors outside of the patient's control) in both adults and children.[9]
Methamphetamine is a Schedule II drug in the United States and is sold under the trademark name Desoxyn.[9]
Desoxyn may be prescribed off-label for the treatment of narcolepsy and treatment-resistant depression.[10]
Recreational use
Methamphetamine is used as a recreational drug for its euphoric and stimulant properties.
Would Dextroamphetamine also give you a positive test for Meth? It still a type of amphetamine. Not sure how all the testing works.