@serenesurface-- That's a great point. And I bet that would cause issues for people who already have liver problems.
The biggest issue though is that the infection that is trying to be treated may remain and worsen. Ciprofloxacin is already the preferred antibiotic for many infections that are not responding to milder antibiotics. So if this too doesn't work because the patient decided to drink, it might become very difficult to get rid of the infection.