Colds are common in autumn and winter, and the tips to prevent colds have attracted much attention. It has been circulating on the Internet that placing an onion in the room can prevent colds, because the sulfur compounds volatilized by the onion can inhibit bacteria and cancer, and purify the indoor air. 
The sulfide contained in onion has a certain inhibitory effect on intestinal bacteria, but it needs to be taken orally every day
 putting a few onions cut at both ends indoors can effectively prevent colds.