Sputum for three weeks may be caused by respiratory tract infection, tuberculosis, heart failure or lung tumor, which should be treated with anti-infection, anti-tuberculosis, stopping or slowing down the development of heart failure, etc., or surgery, radiotherapy and chemotherapy for the tumor. 1. Respiratory tract infections, such as tracheobronchitis, bronchiectasis, chronic obstructive pulmonary disease, etc., should be combined with relevant examinations, such as lung CT, hematology, sputum culture and drug sensitivity test. The underlying disease should be actively treated, and sensitive antibiotics, such as penicillin, ceftriaxone, levofloxacin and other anti-infective treatment should be used under the guidance of specialized physicians. 2. Tuberculosis: sputum culture of Mycobacterium tuberculosis is the “gold standard” for the diagnosis of tuberculosis, and should follow the principle of “early, regular, appropriate amount, the whole process, joint” anti-tuberculosis treatment, and the commonly used drugs are isoniazid, rifampicin, and ethambutol. 3. Heart failure: especially the left heart failure caused by mitral stenosis or other reasons, which can lead to lung stasis, and thus pink foamy sputum, accompanied by different degrees of dyspnea, at this time, digoxin should be given to strengthen the heart for heart failure, furosemide diuretic and other treatments. 4. Lung tumor: if the tumor is accompanied by obstructive pneumonia, there may be mucus sputum. Surgery, radiotherapy and other comprehensive treatments should be chosen for tumor lesions. If you have excessive sputum for three weeks, you should go to regular hospitals in time to find out the cause, actively treat it, and use medicines under the guidance of professional physicians.