I was looking for more information on D-mannose. Specifically how much is too much. Some say too much can cause kidney damage, but they never say how much is too much. I've been taking it for awhile now to help prevent recurring UTIs. For the last six months I also take Methanamine. I'm having my first break through UTI in three months currently and am back on antibiotics. This is the longest I have been without a UTI in two years. I credit the Methanamine and my new doctor.