There is no such thing as a “safe diuretic” in medicine. If you want to take diuretics to produce diuretic effect on the body while minimizing side effects, you should choose according to the patient’s condition and the metabolism of drugs in the body. The main role of diuretics is to promote the body’s potassium ion-based electrolytes and water through the urine discharge, diuretics, spironolactone, aminopterin belongs to the potassium-preserving diuretics, but the diuretic effect is relatively weak; the rest of the diuretics, such as mannitol, furosemide, hydrochlorothiazide in the diuretic at the same time will cause the loss of potassium ions in the body. Diuretics have the following precautions: not too fast, too large a dose, too long, to avoid causing hyponatremia and severe hypotension; close observation of changes in potassium ions; attention to the observation of ototoxicity of furosemide; diuretics to avoid the use of the night, affecting the quality of the patient’s sleep . In conclusion, there is no absolutely safe diuretics, should be combined with the patient’s condition to give the appropriate drugs, patients should follow the doctor’s instructions to take medication.