No, it would say opiate detected - and he could say yes, i took codeine for my back which I bought legally from a chemist. Worse case scenario he would get sent for a blood test or they’d repeat it.
Tolerance to the level of codeine in OTC co-codamol would develop bloody quickly if taken at maximum dose and certainly wouldn’t be doing anything for his back any more. I understand he doesn’t want anyone to know his back is still bad, but if his back was still bad and all he could access was OTC strength co-codamol, he would have been in bed unable to move long before now so that’s a moot point.
Codeine may be addictive but it’s not “highly dangerous” - the amount in an over the counter version is certainly not enough to cause the only real risk of codeine (respiratory arrest) in a healthy person even exceeding the daily dose, unless you’re taking it alongside something that’s contraindicated. The paracetamol with it, however, certainly is dangerous if he’s exceeding the maximum daily dose.
It would make a lot more sense to have Steve sourcing Valium prescriptions dodgily as then he would definitely have something to worry about.
It all just seems really silly to me, very half arsed as a plot line.