BRAND NAMES: Macrodantin, Furadantin, Macrobid. USES: Nitrofurantoin is used to treat or prevent urinary tract infections. SIDE EFFECTS: Common side effects include headache, rash, itching, nausea, vomiting, loss of appetite, diarrhea, and abdominal pain. The macrocrystalline form (Macrodantin) appears to cause less stomach upset.