macrodantin is a nitrofurantoin drug that as you know is used for urinary tract infection, it works by a complex mechanism of damaging the bacterial DNA, now as for side effects it usually causes nausea, vomiting, diarrhea or constipation. it can cause liver damage like jaundice or lung damage but these resolve when drug is discontinued. also it rarely causes nerve damage like dizziness or tingling sensation and they too resolve on discontinuation. now you should know that these side effects are not shown in every patients and there may be no side effects at all, so it mostly depends on patient itself. so if you are sensitive to this and other drugs then i would suggest that you are hypersensitive and should check for allergic reaction before taking any drug. thank you