The main complications are in the acute phase of severe cases. The serious complications in the acute phase mainly include severe circulatory congestion state, hypertensive encephalopathy and acute renal failure. 1, severe circulatory congestion: high water and sodium retention can cause severe circulatory congestion and heart failure, edema, etc.. The manifestations are obvious edema, continuous oliguria or even anuria, shortness of breath, irritability, inability to lie down, and cyanosis. 2, hypertensive encephalopathy: refers to the rapid increase in blood pressure (especially diastolic blood pressure), the emergence of central nervous symptoms. It occurs early in the course of acute nephritis and is usually acute, manifested by severe headache, frequent nausea and vomiting, followed by visual impairment, blurred vision, diplopia, temporary darkness, and drowsiness or irritability, and if not treated in time, convulsions, coma, a few temporary hemiplegia and aphasia, and in severe cases, brain herniation. If the blood pressure exceeds 18.7/12.0kPa (140/90mmHg) and is accompanied by visual impairment, convulsions and coma, one of the three can be diagnosed. 3. Acute renal failure: Only a very small number of patients progress to acute renal failure. Clinical manifestations are oliguria or anuria, increased blood urea nitrogen, blood creatinine, hyperkalemia and metabolic acidosis.