Introduction. Cystitis is one of the most common bacterial infections in women. Postcoital cystitis (PC) is a special form of recurrent cystitis. Non- antibacterial methods of prophylaxis are often ineffective. The use of post-coital antibiotic prophylaxis has a good result, but this approach contradicts the current concept of rational antibiotic use. Therefore, bacteriophages have a high interest among the medical community as an alternative therapy.

Aim. To evaluate the efficacy of bacteriophages using for, use for postcoital prophylaxis in patients with PC.

Material and methods. 33 female patients with PC were recruited into a prospective cohort study by non-inferiority type between 2022 and 2023. All selected patients had previously used non-antibacterial methods of cystitis prophylaxis. Based on the results of urine culture, patients were encouraged to use nitrofurantoin or bacteriophages after sexual intercourse as a PC prophylaxis strategy. The duration of follow-up was 3 months.

Results. In 80% of the patients who used bacteriophage, no episodes of recurrent PC were noted throughout the follow-up period. No side effects were observed. Side effects were noted in five patients taking nitrofurantoin. The efficacy in the control group was 85.7% (p=0.684).

Conclusion. Our data demonstrate that the use of bacteriophage after sexual intercourse to prevent PC may be a safe alternative to antibiotic pro- phylaxis with comparable efficacy.