Regarding laryngitis & sore throat: 20 years ago I was having laryngitis frequently during the winter, then heard about slippery elm powder. I began taking a heaping teaspoon of it mixed with plain yogurt (it has a very chalky texture, hard to dissolve in liquid), every morning and evening, and it not only quickly healed laryngitis I had at the time, BUT, I have NEVER had laryngitis again, nor even a normal sore throat. I read about its properties, & it coats all your mucus membranes from the mouth to the anus, thus also helps with digestion issues & is extremely nourishing. So benevolent I don't see how it could cause problems for anyone, but of course you can find more info on it in herbal books etc. I have been taking it on a fairly regular basis since then; I very rarely ever get a cold, almost never flu, & this may be part of the reason.
(San Diego, Ca)