In general, onions can not treat coughs, the occurrence of cough can be applied to cough suppressing drugs such as dextromethorphan, Pentoxyverine and other treatments. Cough is a protective reaction of the body, when the bronchial mucosa is stimulated by inflammation, foreign bodies, irritating gases, it will cause the bronchial mucosa to secrete increased mucus, and the body will cough to expel the mucus. Bronchial asthma, pneumonia, tuberculosis and other diseases can cause cough. Onions are rich in allicin, quercetin and selenium, which can enhance the body’s immunity. At the same time, selenium has a preventive effect against cancer. However, none of these substances can play the role of cough, so onions can not treat cough. Prolonged cough should be timely to the hospital, improve the relevant examination to clarify the cause of the disease, under the guidance of the doctor symptomatic treatment.