I just started taking d- mannose supplement cause i have a history of utis. my question is can i take this every single day forever for rest of my life to help me prevent ever getting one again and will this harm me doing this.?

From VerywellHealth website: "The optimal dosage of D-mannose and its long-term safety are still largely unknown. The amount taken in studies to prevent UTIs was up to 2 grams daily. D-mannose supplements may cause bloating or loose stools and can alter blood sugar levels. At high doses, there may be serious risks such as kidney damage."

There is no clear scientific evidence for the benefit of mannose. preventing UTI for all time. Best preventive is drinking plenty of fluids, not holding urine, keeping good hygiene in the area, voiding right after sex, avoid constipation and keeping good health. Good luck.