I took 20mg of adderall 3 weeks ago and I have a hair test in the next 2 days. This was a one time use. Will this show up on the hair test? Or is it under the testing thresholds? Any advice would be appreciated. I recognize that other than taking the test there is not much I can do.

A hair test that can go back 90 days can detect the metabolites of adderall, that are very similar to amphetamines. I don't know what the threshold is, but it's a very small dose, and IF detected you better have a prescription.

I passed. No problems.

Lucky you.