When you swallow mullein — tea, drops, capsules, whatever — it goes to your stomach. Your stomach acid destroys most of it before it gets anywhere near your lungs. By the time any reaches your lung tissue, you're getting roughly 5% of what you paid for. It's like swallowing eye drops and expecting them to fix your vision.
And here's what should make you angry: hospitals already know this. When you go to the ER, they don't hand you a pill. They use nebulizers, inhalers, oxygen — everything delivered directly to the lungs. That's how they've always treated lung conditions. So why was everyone selling mullein as drops and teas?
If your lungs are the problem, send the solution to your lungs. Not your stomach.