The World Health Organization has recommended herbal medicine for treatment and control of recurrent cystitis. This study was conducted to determine effect of eshnan on the prevention of recurrent cystitis. The present triple‐blind clinical trial was conducted on 126 women (63 women per group) with recurrent cystitis. The participants were assigned to the intervention and control groups. Three 500‐mg eshnan or placebo tablets were taken orally with a glass full of water by the participants half an hour after each meal for 2 months. The study subjects were clinically and paraclinically evaluated by the end of the second, fourth, and sixth months after the intervention and every time they showed clinical symptoms of cystitis. The present findings showed that the incidence rate of cystitis and symptoms of cystitis was significantly lower in the eshnan group compared with the placebo group 2, 4, and 6 months after the intervention (p < .05). The incidence of recurrent was also significantly lower in the intervention group compared with the control group (p < .001). No side effects were observed in the intervention and control groups. The consumption of eshnan can improve the symptoms of cystitis and prevent the incidence of recurrent cystitis in women of reproductive age.