Elvis Costello recently shared that he actually drank dish soap to protect his voice. An expert once told Costello that he should spray dish soap into his mouth to help preserve his vocals.
Costello said, "My favorite is one a renowned throat doctor told me years ago - he's passed away now but he wrote books about the voice. He told me [to try] one drop of Fairy Liquid in a kind of spray you use to spray your flowers to keep greenfly away."
Costello says the dish soap "stops the cords from sticking." He did clarify the remark, saying: "One drop of dish soap, diluted of course, and he said that stops the cords from sticking. You spray it into your mouth but you can't taste it because it's so diluted."
[Source: Music News; Courtesy of Dr. Dave’s Ultimate Prep]