The most common rejection after kidney transplantation is acute rejection, which usually occurs within six months after surgery. During hospitalization, the main clinical symptoms are decreased urine output, increased creatinine, increased blood pressure, and weight gain. If such conditions occur at home, such as low urine output, fever, high creatinine, etc., patients should pay special attention to the possibility of rejection. At this time, you can touch the transplanted kidney area for swelling, pain, hardness, etc., whether you feel tired, weak, poor appetite, weight gain, etc. Once the symptoms appear, you should go to the hospital for pathological examination or ultrasound examination to make a clear diagnosis.