If every tickle in your throat, slight headache, or mild cough sets off alarm bells these days, you’re not alone. It can be tricky to tell the difference between a cold, the flu, and Covid-19. The good news: Simple precautions that can curb the spread of Covid-19—like wearing a mask, social distancing, and frequent hand washing—can also lower your risk of catching a cold or the flu. Just don’t put much stock in “immune boosting” claims about foods or supplements. Can anything soothe symptoms or shorten your illness? Here’s what we know.