The process of removing a 4mm stone may be painful, depending on the individual’s ability to tolerate it. For most of the patients, 4 mm stones will not be particularly painful during the process of expulsion. 4 mm stones are relatively small, most patients do not have any abnormal reaction during the process of expulsion, and it is not easy to produce a slight numbness and other discomforts after expulsion, which can be recovered within a short period of time in general. Some patients are more sensitive to pain nerves, so even if it is 4 millimeters of small stones, in the process of discharging will feel pain, and accompanied by other discomforts. If there is obvious pain in the process of stone expulsion, the patient can not tolerate, can be prescribed oral antispasmodic analgesic drugs, such as atropine and so on. Oral medication, drinking plenty of water and exercising are usually recommended for stones as small as 4 millimeters. However, if the stone has not been able to be discharged, it is recommended to consult a doctor in a timely manner, and under the guidance of the doctor for professional management.