Markus83 9 Nov 2018 09:37 am I'm taking Azi + Rifa at the… I'm taking Azi + Rifa at the moment. The problem with rifampicin is that it is a heavy inducer of the CYP450 liver system. That means that many drugs - including rifampicin itself - get metabolized much faster. Where possible, I would recommend measuring blood levels of your antibiotics before starting rifampicin and then again 3 weeks or so later. Maybe you need to increase dosage of you medications.