I bought a home breathalyzer device, and I have a question or two concerning it's test results.?

My husband was an active alcoholic in his youth, but was clean for over 22 yrs. We have only been married just shy of 7 yrs. He had gone thru rehab successfully, and continued in AA for a while, but his ex never followed thru in Alanon. Shortly after we married, I discovered he was beginning to drink again, he thought he could handle it, but couldn't. He has been hiding cheap bottles of Vodka in various places, even had one hidden away from our house, enroute to his AA meetings that he had to start going back to. But I couldn't trust him, and was scared he'd wreck the car to or from, and I didn't care to be his chauffeur either. I eventually had to buy a breathalyzer because he did nothing but lie, and even when this breathalyzer show's that he has, he denies, denies , denies. But, is there a chance that some medication that he takes could be causing the detection? He doesn't seem drunk, and his speech isn't slurred, not like it was before......can somebody please tell me if there is that chance of medication, or I'm I being fed a line....again. Please, only those who know about these things for a fact reply to this....please. Thank you.