Zefwel O Syrup is an antibiotic medicine given to children for the treatment of a wide range of bacterial infections. These may include middle ear infections, sinusitis, pharyngitis, tonsillitis, pneumonia, skin and soft infections, abdominal infections, and urinary tract infections. This medicine works by inhibiting the growth of infection-causing bacteria by stopping it from multiplying. As a result, the infection starts clearing within 3 to 5 days of regular dosing. However, continue giving the medicine as prescribed by the doctor because stopping the medicine abruptly may worsen your childâs condition or bring back the infection.