Coughing up a lot of brown sputum generally means rusty sputum looks like brown color, which may be caused by tuberculosis, lung cancer, bronchial dilatation, etc. It is treated by medicines such as amoxicillin, etc., and surgery. 1. Lobar pneumonia: red blood cells penetrate into the alveoli, hemoglobin in red blood cells decomposes, and ferrohemoglobin mixes into the sputum, making the sputum rust-colored, mostly caused by Streptococcus pneumoniae. Expectorant drugs, such as acetylcysteine, can be used as prescribed by the doctor. Meanwhile, patients can use antibiotics according to the pathogenic bacteria for treatment, such as amoxicillin, cefixime and so on. 2. Lung cancer: when lung cancer invades small or big blood vessels, bleeding symptoms will also appear, which will be coughing and bleeding, and the blood will be oxidized by air and will show brown color. Small cell lung cancer is mainly treated with chemotherapy or a combination of radiotherapy and chemotherapy. Non-small cell lung cancer can be treated in many ways, including surgery, chemotherapy, molecular targeted therapy and so on. 3. Bronchial dilatation: it is mainly due to the rupture of blood vessels in the submucosa caused by purulent inflammatory stimulation. If there is old bleeding, the sputum coughed up will be brown in color. Use expectorants, such as ambroxol, and bronchodilator drugs, such as salbutamol, as prescribed by the doctor. If necessary, postural drainage can be used. For moderate or massive hemoptysis, hemostatic drugs such as posterior pituitary hormone are used. Surgery can be considered to remove the lesion if medication is not effective. Coughing a lot of brown sputum can also be seen in fungal infections, long-term exposure to dust, etc., you should go to the hospital in a timely manner, improve the relevant laboratory tests and assessments, a clear diagnosis under the guidance of the doctor for treatment.