Objective: In patients with bipolar disorder (BD), rapid cycling (RC) presents a risk for a more severe illness, while euthymia (EUT) has a better prognosis. This study focused on the progression of RC and EUT, which are contrasting phenomenology, and aimed to clarify the influence of patient backgrounds and prescription patterns on these different progressions, using a large sample from the first and second iterations of a multicenter treatment survey for BD in psychiatric clinics (MUSUBI)., Methods: In the cross-sectional study (MUSUBI), a questionnaire based on a retrospective medical record survey of consecutive BD cases ( N = 2,650) was distributed. The first survey was conducted in 2016, and the second one in 2017. The questionnaire collected information on patient backgrounds, current episodes, and clinical and prescribing characteristics., Results: In the first survey, 10.6% of the participants had RC and 3.6% had RC for two consecutive years, which correlated with BP I (Bipolar disorder type I), suicidal ideation, duration of illness, and the use of lithium carbonate and antipsychotic medications. Possible risk factors for switching to RC were comorbid developmental disorders and the prescription of anxiolytics and sleep medication. Moreover, 16.4% of the participants presented EUT in the first survey, and 11.0% presented EUT for two consecutive years. Possible factors for achieving EUT included older age; employment; fewer psychotic symptoms and comorbid personality disorders; fewer antidepressants, antipsychotics, and anxiolytics, and more lithium prescriptions., Conclusion: RC and EUT generally exhibit conflicting characteristics, and the conflicting social backgrounds and factors contributing to their outcomes were distinctive. Understanding these clinical characteristics may be helpful in clinical practice for management of patients with BD., Competing Interests: MK has received grant funding from the Japanese Ministry of Health, Labor and Welfare, the Japan Society for the Promotion of Science, SENSHIN Medical Research Foundation, the Japan Research Foundation for Clinical Pharmacology, and the Japanese Society of Clinical Neuropsychopharmacology and speaker’s honoraria from Sumitomo Dainippon Pharma, Otsuka, Meiji-Seika Pharma, Eli Lilly, MSD K.K., Pfizer, Janssen Pharmaceutical, Shionogi, Mitsubishi Tanabe Pharma, Takeda Pharmaceutical, Lundbeck, and Ono Pharmaceutical, and participated in an advisory/review board for Otsuka, Sumitomo Dainippon Pharma, Shionogi, and Boehringer Ingelheim. YK has received consultant fees from Pfizer and Meiji-Seika Pharma and speaker’s honoraria from Meiji-Seika Pharma, MSD, Eli Lilly, Janssen Pharmaceutical, Dainippon Sumitomo Pharma, Mitsubishi Tanabe Pharma, Yoshitomi Yakuhin, Otsuka Pharmaceutical, Takeda Pharmaceutical, Lundbeck Japan, and Eisai. TA has received speaker’s honoraria from Eli Lilly, Otsuka Pharmaceutical, Sumitomo Dainippon Pharma and Eisai. HU has received manuscript fees or speaker’s honoraria from Eisai Co., Ltd., Janssen Pharmaceutical, Kyowa Pharmaceutical, Meiji Seika Pharma, Otsuka Pharmaceutical, Pfizer, Shionogi, Dainippon Sumitomo Pharma, Takeda Pharmaceutical, Lundbeck Japan, and Yoshitomi Yakuhin. KE has received speaker’s honoraria from Eli Lilly, Meiji Seika Pharma, Mitsubishi Tanabe Pharma, MSD, Otsuka Pharmaceutical, Pfizer, Sumitomo Dainippon Pharma, Kyowa, Yoshitomi Yakuhin, and Takeda Pharmaceutical. EK has received speaker’s honoraria from Daiichi Sankyo, Eisai, Eli Lilly, Janssen Pharmaceutical, Kyowa Pharmaceutical, Meiji Seika Pharma, Mitsubishi Tanabe Pharma, MSD, Otsuka Pharmaceutical, Pfizer, Sumitomo Dainippon Pharma, UCB, and Viatris. SH has received manuscript fees or speaker’s honoraria from Eli Lilly, Janssen Pharmaceutical, Kyowa Pharmaceutical, Meiji Seika Pharma, Mitsubishi Tanabe Pharma, Mochida Pharmaceutical, Ono Pharmaceutical, Otsuka Pharmaceutical, Pfizer, Shionogi, Sumitomo Dainippon Pharma, Takeda Pharmaceutical, and Yoshitomi Yakuhin. EG has received manuscript fees or speaker’s honoraria from Eli Lilly, Janssen Pharmaceutical, Meiji Seika Pharma, Mitsubishi Tanabe Pharma, MSD, Otsuka Pharmaceutical, Takeda Pharmaceutical, Eisai, Ono Pharmaceutical, Kyowa Pharmaceutical Industry, and Sumitomo Dainippon Pharma. RY has received speaker’s honoraria from Eli Lilly, Dainippon Sumitomo, Otsuka, and Esai. AN has received speaker’s honoraria from Pfizer, Eli Lilly, Otsuka, Janssen Pharmaceutical, Mitsubishi Tanabe Pharma, Mochida, Dainippon Sumitomo, and NTT Docomo, and participated in an advisory board for Takeda, Meiji Seika, Tsumura, and Yoshitomi Yakuhin. TKik has received consultant fees from Takeda Pharmaceutical and the Center for Cognitive Behavioral Therapy and Training. TT has received consultant fees from Pfizer and speaker’s honoraria from Eli Lilly, Meiji-Seika Pharma, MSD, Janssen Pharmaceutical, Dainippon Sumitomo Pharma, Mitsubishi Tanabe Pharma, Yoshitomi Yakuhin, Mochida Pharmaceutical, Otsuka Pharmaceutical, Kyowa Pharmaceutical, and Takeda Pharmaceutical. KW has received manuscript fees or speaker’s honoraria from Daiichi Sankyo, Eisai, Eli Lilly, GlaxoSmithKline, Janssen Pharmaceutical, Kyowa Pharmaceutical, Meiji Seika Pharma, Mitsubishi Tanabe Pharma, MSD, Otsuka Pharmaceutical, Pfizer, Shionogi, Sumitomo Dainippon Pharma, Takeda Pharmaceutical, and Yoshitomi Yakuhin, has received research/grant support from Daiichi Sankyo, Eisai, MSD, Mitsubishi Tanabe Pharma, Meiji Seika Pharma, Otsuka Pharmaceutical, Pfizer, Shionogi, Sumitomo Dainippon Pharma, Takeda Pharmaceutical, and is a consultant for Boehringer Ingelheim, Daiichi Sankyo, Eisai, Eli Lilly, Kyowa Pharmaceutical, Lundbeck Japan, Otsuka Pharmaceutical, Sumitomo Dainippon Pharma, Taisho Toyama Pharmaceutical, Takeda Pharmaceutical, and Viatris. NY-F has received grant/research support or honoraria from, and received speaker’s honoraria of Dainippon-Sumitomo Pharma, Mochida Pharmaceutical, MSD, and Otsuka Pharmaceutical. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Takano, Kato, Adachi, Kubota, Azekawa, Ueda, Edagawa, Katsumoto, Goto, Hongo, Miki, Tsuboi, Yasui-Furukori, Nakagawa, Kikuchi, Watanabe, Kinoshita and Yoshimura.)