Lithium carbonate 2 tablets and 3 tablets (500-750mg) are both in the therapeutic dosage range (600-2000mg per day), with the difference being in the therapeutic dose. The main role of lithium carbonate is the treatment of manic state/bipolar disorder and prevention of relapse, and it is also effective in recurrent depression. Generally speaking, adults calculate the dosage according to the body weight 20~25mg/kg to achieve the therapeutic effect. 2 tablets or 3 tablets in a single dose can maintain different concentrations of blood lithium concentration to achieve different therapeutic effects. As lithium carbonate is irritating to the stomach, too much in a single dose may cause stomach upset. The use of lithium carbonate needs to be alert to lithium toxicity, different individuals have different sensitivity to blood lithium concentration, too high blood lithium concentration will lead to dizziness, lack of coordination, apathy, drowsiness, tinnitus, convulsions and even death. The use of lithium carbonate must be regularly and accurately monitor the blood lithium concentration, is prohibited in allergy, severe renal impairment. Adverse effects of lithium carbonate include fatigue, vertigo, ataxia, tinnitus, nausea and vomiting. In summary, lithium carbonate requires strict dosage control and must be replaced under the guidance of the clinician, taking the medication as prescribed to avoid serious adverse events.