Saline Solution

"The latest findings indicate that using a nebulizer with isotonic saline can reduce your Phonation Threshold Pressure (PTP) as well as your Perception of Phonatory Effort (PPE), meaning it takes less pressure for your vocal folds to create sound." - Vocal Mist's Website

Except they sell it for $128!!!

I found this cheaper alternative on Amazon. I use it in my nebulizer and I'm obsessed:

https://amzn.to/47qbIvm