Milk and Mucus
Most people believe that when they are sick with a cough, they should avoid milk or dairy products in general because this type of food will generate more phlegm and make their cough worse. This is an extremely popular misconception, and it's cross-generational as well as cross-cultural.
This myth may have arisen from the sensation many people feel after they drink milk. It's a sticky sensation at the back of the throat, as though something was coating it. An Australian hospital has conducted a study in which they had fifty-one healthy volunteers willingly infect themselves with a cold virus, and the researchers measured the amount of snot they subsequently produced. The consumption of milk varied from eleven glasses a day to none at all, but the “snot production” factor had no correlation with the amount of milk they drank. Scientists have sought to discredit the belief of increased phlegm production because this myth has actually reduced the consumption of dairy products in the past.
In fact, milk might even improve cold symptoms because it is a good source of fluid and nutrition. It's jam-packed with vitamins and protein, providing the body with fuel and raw material for building more germ-fighting cells. So drink up! Milk really does a body good, even when you're sick.
Of course, if your child is already feeling nauseated and threw up the last time she tried drinking milk, don't force the issue. It's not that the milk will make more mucus, but if your child can't keep the milk down, there is no point in trying to drink and throwing up right afterward.