It takes energy to do that. Many people are convinced that vitamin C can prevent colds or relieve symptoms. There is no conclusive evidence of this, but the vitamin may reduce the severity or duration of symptoms, according to the National Institute of Allergy and Infectious Diseases. But taking vitamin C in large amounts over long periods can be harmful, sometimes causing diarrhea and distorting common medical tests of the urine and blood. Another proposed therapy, interferon-alpha nasal spray, can prevent infection and illness but causes unacceptable side effects like nosebleeds, according to the institute.
Many patients have their own, unproven theories about what works.
It may soothe a sore throat, unstuff clogged passageways, and hydrate a thirsty body. Psychologically, that's important when you're sick.