Lithium carbonate is mainly used to treat mania and has a good therapeutic and relapse prevention effect on bipolar disorder with alternating episodes of mania and depression. Patients may experience the following side effects after long-term use of lithium carbonate, including dry mouth, irritable thirst, excessive drinking, polyuria, constipation, diarrhea, nausea, vomiting, and epigastric pain. Neurological side effects may also occur, such as tremor of the hands, depression, weakness, drowsiness, blurred vision, hyperactive tendon reflexes, and possibly elevated white blood cells. Aggravation of these side effects may be a sign of toxicity and should be closely monitored. Because of the low therapeutic index of lithium salts, the therapeutic and toxic amounts are close to each other, the blood lithium concentration should be monitored to help regulate the therapeutic and maintenance amounts and detect acute toxicity in time. When taking the medication, attention should be paid to the large loss of body fluid, such as persistent vomiting, diarrhea, and profuse sweating, which can easily cause lithium toxicity. Therefore, a low-salt diet is not allowed during drug administration, and renal and thyroid functions should be checked regularly for patients on long-term medication.