Personally, I don't use them. Although I have plenty of friends who are singers who swear by these products. Years ago I did use them, but I quickly came to the conclusion that they didn't work any better than say, Celestial Seasonings Chamomile tea.
It is truly more about hydration. Anything that hydrates is gonna make the throat feel better for a while. The slippery elm in these teas is the active ingredient. Its a demulcent that forms a soothing film over the mucus membrane helping to reduce minor pain. So after drinking a tea w/slippery elm, yes, I'd say we'd feel a soothing effect on our throats....for a few minutes. It doesn't take long to wash away, unfortunately.
If a singer's chords are inflamed, the slippery elm helps if you "inhale" the tea as you drink it. Or better yet, boil the tea in a saucepan, put your head over it and cover with a towel to inhale the vapors... they are the only thing that will touch the chords. Our vocal chords have two functions. One is to help produce tone for speaking....and in our case singing. The other is to keep all food, liquids and God-knows-what-else-someone-out-there-is-willing-to-ingest, out of the lungs. When anything accidentally touches the chords, they start vibrating vehemently to expel whatever is lodged on them. Its the "something-went-down-the-wrong-way" cough. So therefore any herbal tea is not going to coat the chords, but will certainly feel good on the vocal track, i.e., the pharynx and larynx. But the tea's properties are delivered to the chords through the vapor. Alas, this feel-good effect doesn't last long. And we can't be "steaming" while on stage.
Best remedy for a sore throat is -- of course -- vocal rest... but that's pretty much impossible if you're a professional singer. Can't cancel gigs if the club owner is counting on you, tickets have been sold, and your band mates have already spent their gig money. OK maybe that's just a lot of the musicians I know. Any-hoo, as the saying goes, the show must go on. This is why we need to know vocal technique and understand our instrument and how to use it. There are certain techniques and "tools" -- as I call them -- that will help us minimize and even prevent the damage. But you'll have to schedule a lesson for those. :)
Cover band artists have it the worst. Those poor singers have to sing 30 to 40 songs per gig and many times need to repeat that performance the next night. Plus, the conditions they sing in can be very difficult... bad monitors, bad acoustics, guitarists who keeps turning up their guitar volume. Oh, sorry to any guitarists reading, but you guys do have a reputation. But I digress. The good news is it can be done! Singers just need the right training. I know because I've done it. I've sang 30/40 songs per gig night after night. Never canceled a gig -- ok, once when in bed with 103 temp but really, I was so sick that my hair hurt!! -- and I never developed nodules because of my technique and knowledge of my own instrument. Our vocal instruments and bodies vary from person to person so we need to know how our individual setup works. But that seems like another fun subject... for another post. Just remember -- what works for one singer may actually not work for another.
Ok, let's get back on track. Medicinal teas and lozenges. Just because something is made of herbs doesn't mean it's good for you. Some teas contain undesirable substances like nicotine or alkaloids that can be toxic in large doses. Horsetail and lobelia contain nicotine and comfrey tea contains an alkaloid that can cause liver damage. Plus these chemicals can stay in the body for a long time. Make sure you check the labels and know what your consuming. If you see an herb that you're unfamiliar with, Google it. But slippery elm I don't think has any adverse side effects and its the main ingredient in most feel good teas. Licorice is usually used also. Has a bit of a "menthol" effect. Tastes good too.
So, my final words about medicinal teas... they work, but not as well or as long as the manufacturers, would have you believe. Surprise, surprise. They will make your throat feel better while you are drinking them and for a few minutes after. They will not touch or impact the chords, except for their vapors. Same thing with lozenges (like Vocal Zone). They feel good on your throat while they are in your mouth, and they help minimize potentially harmful coughs.
So, what's your secret remedy for soar throats, singers? Any thoughts on Throat Coat or any information on other brands of herbal teas?