Methenamine mandelate is commonly used in the treatment and prevention of urinary tract infections (UTIs). It works by converting to formaldehyde in acidic environments, such as in the urine, which then acts as an antibacterial agent to inhibit the growth of bacteria in the urinary tract. This makes it particularly effective against pathogens like Escherichia coli and other gram-negative bacteria. It is often prescribed for long-term prophylaxis in patients prone to recurrent UTIs, especially in cases where other antibiotics may not be suitable. Additionally, it is sometimes used in veterinary medicine for similar purposes. The mandelic acid component further enhances its antibacterial properties by maintaining an acidic pH in the urine, which is unfavorable for bacterial growth.