I've never heard of cortisol causing a positive test for meth. Cortisol is a naturally produced hormone in the body and I'm pretty sure it has NO chemical similarity to amphetamines. But taking amphetamine salts in the form of adderall (among other stimulants) often causes people problems for drug test if there taking them without a prescription
i dont think cortisol has amphetamines in it which is what will make you test positive for meth