I think it's helped me, but it's hard to say definitively. I started it about 10 years ago when my PA was starting to act up on a regular basis. The time between my PA exacerbations increased considerably after I began Zithro. It could just be a coincidence, but I won't stop taking Zithro unless I have a really good reason. While I think it's helpful in long term management, it's not like it makes me feel like a rock star 24/7. Its effectiveness probably varies quite a bit depending on genetics and/or current bugs.