The concept of saline nasal irrigation, or bathing the nasal passages with a saltwater solution, is thought to have been introduced as part of Ayurveda, an alternative medicine system that originated in the Indian subcontinent more than 5,000 years ago. Now, modern science is beginning to demonstrate that this ancient practice really does serve as a surprisingly effective shield against many of the seasonal bugs behind the common cold. According to Paul Little, a professor in primary care research at the University of Southampton who led both studies, sodium chloride—the chemical name for salt—is capable of stimulating a natural antiviral mechanism within the nose. During the early stages of the Covid pandemic, many health care professionals dismissed the suggestion that saline nasal irrigation might be able to prevent infections. “Clinicians and researchers have started paying increasing attention to saline nasal irrigation because it helps, and it is natural, easy to understand care,” says David Rábago, a physician and professor at Pennsylvania State University College of Medicine.