Because there are multiple causes, not just allergies. Elevated eosinophils could indicate allergies, asthma, infection (mostly due to parasites), even cancer. I think my case it was allergies but I did have trace pseudomonas which may go away on its own but taking the 10 days of antibiotic. Years ago, an NJH Pulmonologist put me on Montelukast for elevated leukotrienes and eosinophils. I remember feeling absolutely great on that drug until it started making me nauseated. I was so disappointed that I could not take for my situation-reactive airway mostly triggered by asthma. I recently asked my doctor if I could try it again-a lower dose, but it wasn't recommended while I was fighting MABs.
Just an FYI: You may know this? Taking Azithromycin while infected with an NTM may lead to macrolide resistance and your NTM could be very difficult to treat. People go years with undiagnosed NTMs, take zpaks, and then learn their NTM is macrolide resistant. My MABs is/was macrolide resistant and subsequently has only a 50% rate of culture conversion with antibiotics. I say is/was because I so far have had 2 negative tests and waiting on 3rd. I'm praying for a 3rd negative.