Health - Bad drug test surprise: hair

[Censor]

First off, apologies if this isn't in the right forum. I've checked the others I could see but of course it's possible I've overlooked something.

SWIM knew he had a drug test coming up so didn't take any codeine/trams for 3 weeks beforehand thinking they'd be out of his body by then so he'd be fine. However, when he got there he found that it wasn't a piss test but a HAIR test. SWIM is worried now. He put on the form thing that he'd had OTC 12.8/500 Codeine Phosphate Hemihydrate / Paracetamol tabs in the previous fortnight, but thinks that won't be enough. Should he start preparing for the worst?