Q. Why do they tell you to drink extra fluids when you are sick? Does it really do any good?
A. Drinking extra water or other fluids can help a sick person, but not by flushing the germs from the bloodstream, as many people have been led to believe.
Fluids are recommended to keep a person hydrated when sick, said Dr. Shari Midoneck, an internist at the Iris Cantor Women’s Health Center of NewYork-Presbyterian/Weill Cornell Medical Center.
Someone with a fever or diarrhea or someone who is vomiting is losing fluids that need to be replaced, she said. A patient who does not drink enough fluids to replace the losses can become hypotensive, meaning that the blood pressure is abnormally low, and the person can, in severe cases, pass out.
“But the fluids do not flush out bacteria or viruses in your blood,” she said. “Only antibiotics or time can do that.”
That does not mean that the cleansing power of fluids is not important, Dr. Midoneck said, particularly in specific kinds of infection.
“In the case of urinary tract infections,” she said, “drinking a lot of fluids will keep things moving through the urinary tract and could potentially prevent infection by flushing away bacteria that could have adhered to the wall of the bladder.”