Oxygen saturation below 90% can be given promptly with oxygen therapy, e.g. nasal cannula, mask oxygen. Relief of discomfort. The cause may be pneumonia, bronchial asthma, hypoxemia and other diseases, can take medication as well as general measures to improve. 1. Pneumonia: For Streptococcus pneumoniae, patients can take cephalosporins as prescribed by the doctor, such as cefoperazone, ceftriaxone and so on. If it is caused by mycoplasma infection, patients can take tetracycline drugs, such as minocycline, doxycycline and so on. If the pneumonia is caused by viral infection, patients can take antiviral drugs for treatment, such as ribavirin, acyclovir and so on. Patients need to rest, eat a light diet, and quit smoking and drinking. 2. Bronchial asthma: For bronchial asthma caused by oxygen saturation is lower than 90%, patients can follow the doctor’s prescription inhalation glucocorticosteroid aerosol treatment, such as beclomethasone, budesonide and so on. Some patients can also follow the doctor’s prescription inhaled beta 2 agonist treatment, such as salbutamol, terbutaline, etc.. Patients need to avoid contact with allergens in daily life, and do not exercise strenuously. 3. Hypoxemia: For the oxygen saturation of blood caused by hypoxemia is lower than 90%, patients can be nebulized inhalation bronchodilator treatment, such as ciclesonide, ipratropium bromide and so on. Patients need to rest more in daily life and avoid overwork. It is recommended that patients with oxygen saturation below 90 percent need to consult a doctor in time to check the cause of the disease, and the doctor will choose the appropriate measures for treatment after clarifying the cause of the disease.