Association of the Japanese herbal kampo medicine kakkonto with antibiotic use and surgical drainage for noninfectious mastitis: A nationwide database study

Aim: Kakkonto, a Japanese herbal kampo medicine, is empirically prescribed to improve milk stasis and ameliorate breast inflammation in patients with noninfectious mastitis. We investigated whether early use of kakkonto is associated with a reduction in antibiotic use and surgical drainage in patients with noninfectious mastitis.Methods: We identified 34 074 patients with an initial diagnosis of noninfectious mastitis within 1 year of childbirth between April 2012 and December 2022 using the nationwide administrative JMDC Claims Database. Patients were divided into the kakkonto (n = 9593) and control (n = 9648) groups if they received and did not receive kakkonto on the day of the initial diagnosis of noninfectious mastitis, respectively. Antibiotic administration and surgical drainage within 30 days after the initial diagnosis of noninfectious mastitis in the two groups were compared using propensity score-stabilized inverse probability of treatment weighting analysis.Results: The frequency of antibiotic administration within 30 days after the initial diagnosis of noninfectious mastitis was significantly lower in the kakkonto group than in the control group (10% vs. 12%; odds ratio, 0.88 [95% confidence interval, 0.80-0.96]). The frequency of antibiotic administration during 1-3 and 4-7 days after the initial diagnosis were also significantly lower in the kakkonto group than in the control group. The frequency of surgical drainage did not differ significantly between the two groups.Conclusions: Kakkonto was associated with reduced administration of antibiotics for noninfectious mastitis, making it a potential treatment option for relieving breast inflammation and promoting antimicrobial stewardship.