Anyone taken Nitrofurantoin & had adverse effect on B12 levels? Had them prescribed for UTI, says on info leaflet to TAKE SPECIAL CARE if you have 'a lack of Vitamin B or abnormal levels'. There is no specific reference to Vitamin B12, so are they just generalising. e.g any type of vitamin B deficiency to cover all bases ?(think there are 8 types of vitamin B but how would you know if you were deficient in any other than B12?), it seems rather vague & anything BUT informative? It doesn't come under the DO NOT TAKE IF heading, so maybe its just a case of extra B12 needed whilst taking it? Any advice appreciated as I need to take something to clear the UTI.