Taking inhalers for emphysema once a day. how long can i take this before lungs become immune to medicine?

Unlikely: In longterm studies patients do not typically become immune to their inhalers. In a certain class of drugs called beta agonists (albuterol, salmeterol) you may become less responsive to the effects overtime but this can be prevented by taking a holiday (up to a few months) from the medication under your healthcare providers supervision.

They usually don"t: The once daily inhaler for emphysema is spiriva, you don't become immune or cease to respond to it. The newer once daily is arcapta; it is too new for any data on this but it belongs to a class of medicines to which you body may become accustomed to. Hope this helps.