The therapeutic efficiency and safety of the proteolytic enzyme bromelaine obtained from pineapple (Bromelain-POS, Ursapharm GmbH, Saarbrücken, Germany) was evaluated in children under the age of 11 years diagnosed with acute sinusitis. Data from 116 patients from 19 centres located across Germany were analysed in a pharmacoepidemiological cohort study. Patient cohorts were either treated with Bromelain-POS (N = 62), in combination with Bromelain-POS and standard therapies (N = 34), or with standard therapies (N = 20). The primary parameter measuring effectiveness of the different treatment groups was the duration of symptoms. The shortest mean period of symptoms was observed in patients treated with Bromelain-POS alone (6.66 days), followed by the standard therapy (7.95 days) and those treated with a combination of Bromelain-POS and the standard therapy (9.06 days). Patients of the Bromelain-POS monotherapy group showed a statistically significant faster recovery from symptoms (p = 0.005) compared to the other treatment groups. One 10-year-old male patient, with a known pineapple allergy, showed a self-limiting mild allergic reaction. No other unwanted side-effects were reported. This trial documents that the proteolytic pineapple enzyme Bromelain-POS is widely used in the treatment of young children diagnosed with acute sinusitis in Germany and that the use of proteolytic enzymes can benefit such patients.