I'd been using D-mannose for about 6 months and thought it was wonderful. I get frequent UTIs and hadn't had one since starting D-Mannose. I guest I got a bad batch or something, all of a sudden they started making me really really sick. I took them one morning (fresh bottle) and got violently ill. I took a few days off and felt fine then tried again and the same thing happen. I felt so terrible that I can make myself try again even though it might of just been that batch.