He took one hit of weed and about puked and took another small hit about three weeks ago. it was his first time smoking will he pass a hair drug test?

Possibly: It's possible that a hair analysis could be possible.

Yes: Addiction specialist here. Cannabis is one of the few drugs that is not the most reliably found in hair testing because it is lipophilic-- ie likes fat cells. But the pot problem is a bigger issue here. Brand new science on ptsd and schizophrenia in cannabis exposure in the ages of 15 to 25. Even a one time hit.

Maybe not.: Cannabis usually is detected in a hair drug test for up to 90 days.