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20Lithium is the basic drug used in the pharmaco-therapy of bipolar disorder and is listed as the first-line drug in the treatment guidelines of many countries and it is included in the WHO Model List of Essential Medicines (https://list.essentialmeds.org/). In Japan, lithium carbonate is used. Lithium is effective in improving manic and depressive states, preventing recurrence of manic and depres-sive states, and preventing suicide. However, lithium is associated with many side effects, and because of the proximity of the safe and toxic concentrations, regular measurement of blood levels is necessary. Blood levels should be measured at the beginning of treatment and once every two to three months after stabilization. The effective blood level is between 0.4 and 1.2 mM, and toxicity is more likely to occur when the level exceeds 1.5 mM.Side effects such as diarrhea, anorexia, thirst, polydipsia, and polyuria are seen when lithium is started. Hand tremor may persist even in the effec-tive concentration range. In the case of intoxica-tion, various symptoms appear, such as cerebellar ataxia, gait disturbance, consciousness disturbance, and vomiting. Since hypothyroidism is often observed, TSH, free T3, and free T4 should be checked regularly. Even if hypothyroidism is observed, lithium treatment can be continued by taking thyroid hormone.Since concomitant use of non-steroidal anti-in-flammatory drugs may increase lithium blood levels, attention should also be paid to concomitant medications. Lithium toxicity is more likely to occur during dehydration. Long-term use of the drug may cause renal dysfunction due to interstitial nephritis, etc. Therefore, a regular check of renal function is necessary. Calcium levels should also be measured periodically while taking lithium, as lithium may cause hyperparathyroidism.Lithium is contraindicated in pregnancy in Japan due to the increased risk of cardiovascular malfor-mations in the fetus when taken during pregnancy, but it has been reported that there is no significant increase in risk when the dose is 600 mg or less per day16), and revisions to the drug information are expected.Various other side effects have also been reported, but due to the limited availability of medi-cations for the treatment of bipolar disorder, we should not give up easily when side effects occur and consider measures to minimize them.Among the anticonvulsants used as mood stabi-lizers, lamotrigine alone is indicated for the mainte-nance treatment of bipolar disorder in Japan. It is effective in preventing relapses and recurrences of all episodes, but the main effect of lamotrigine is to prevent depressive episodes.Valproic acid has been shown to be effective in manic states. Clinical trials of its prophylactic effect have not been successful, and it does not show a significant prophylactic effect against placebo, and its prophylactic effect is reported to be inferior to that of lithium, but it is also used as a prophylactic drug in clinical practice because meta-analyses suggest its efficacy. Carbamazepine was found to have an effect on manic states in Japan. Some small trials are suggesting a prophylactic effect, but the evidence is insufficient. Of these antiepileptic drugs, valproic acid and carbamazepine are indicated by insurance for the measurement of blood levels under the name of manic-depressive illness.For the manic state of bipolar I disorder, many atypical and typical antipsychotics have been effec-tive, as well as lithium, valproate, and carbamaze-pine.For the depressive state of bipolar disorder, three atypical antipsychotics, quetiapine, olanzapine, and lurasidone, have been shown to be effective and are indicated in Japan.Although not covered by insurance, prophylactic effects have been shown for olanzapine, aripipra-zole, and quetiapine. The prophylactic effect of quetiapine is mainly for the prevention of depres-sion. In addition, sustained injection of aripiprazole has been shown to prevent relapses and recur-rences of bipolar disorder and was covered by insurance in 2020. The preventive effect of aripip-razole is only for the prevention of manic states.Psychotherapy alone is not effective in treating LithiumAnticonvulsantsAntipsychoticsPsychotherapy