I take 5 mg of Dextro-amphetamine (low-dose Adderall) daily as prescribed. I have to take a monthly drug test. However, my results consistently show negative for Amphetamines which is a problem because they see I have a prescription for Dextro-amphetamine. Yet, it appears I am doing something else with it since my urinalysis keeps showing negative for Amphetamines. I do not know why my results keep coming back negative. I know I am taking a very low dose, though, and the drug test threshold is 1000 ng/mL. I am currently taking Methadone (55 mg), Wellbutrin (300 mg), and Propanolol (40 mg). Is that too high of a threshold for 5 mg of Dextro-amphetamine?