Kidney stones of 4 millimeters usually do not cause any symptoms, may occasionally have swelling and pain in the lower back, if the stone enters the ureter can cause renal colic. A 4-millimeter kidney stone does not usually cause any symptoms because it does not create an obstruction, and may occasionally cause swelling and pain in the lower back. If the stone enters the ureter and becomes a ureteral stone, it can cause renal colic, which is characterized by severe pain in the lower back and abdomen, nausea, vomiting, blood in the urine, and frequent urination. If you suspect that urinary stones can do the urinary system ultrasound to confirm the diagnosis, 4 mm stones can be naturally discharged through more exercise, drink more water, if the pain is more intense, you can use pain medication, such as diclofenac sodium, indomethacin suppositories and so on.