He didn't tell me not to use it. This was my first visit and long with lots of info going back and forth. I had not started nebulizing or any "formal" ACT's. I'd been given an Acapella by a previous doctor. I think he was amazed my lungs looked so good. He said I was a lucky woman.
Now I know diffusers can be a bad idea and harbor bacteria. I use the simplest I can find and disinfect each refill. I use sterile distilled water. I also passive diffuse which is putting the oil on objects made for this or simply a few drops on a cotton ball. The oil itself is antibacterial.
I will ask him my next visit.