A Japanese study found that popular flu-fighters Relenza and Tamiflu had reduced effectiveness due to excessive use. Doctors generally prescribe the drugs for those combating the beginnings of the influenza B strain or those in immediate contact with someone who has the flu.

“These drugs should not be given when you hear on the news that miles away someone has the flu,” said Dr. Marc Siegel, a clinical associate professor of medicine at New York University School of Medicine.