These reactions usually occur after exposure to the drug for more than 6 weeks. The onset of chronic active hepatitis may be insidious, and patients should be monitored periodically for changes in biochemical tests that would indicate liver injury.
Hepatic reactions, including hepatitis, cholestatic jaundice, chronic active hepatitis, and hepatic necrosis, occur rarely. It is important to recognize nitrofurantoin as possible cause of symptoms and discontinue the drug when the suspicion of pulmonary side effects arises as it can be reversible if the drug is stopped early. This reaction manifests with progressive shortness of breath. This uncommon reaction may occur 1 month to 6 years after starting the drug and is usually related to its total lifetime dose. Ĭhronic pulmonary reactions caused by nitrofurantoin include diffuse interstitial pneumonitis, pulmonary fibrosis, or both. Treatment includes discontinuation of the nitrofurantoin, which should result in symptom improvement within 24 hours. Chest radiograph will often show unilateral or bilateral infiltrates similar to pulmonary edema. Symptoms include fever, dyspnea, chills, cough, pleuritic chest pain, headache, back pain, and epigastric pain. These reactions usually develop 3–8 days after the first dose of nitrofurantoin, but may occur from a few hours to a few weeks after starting the drug. Acute reactions have been estimated to occur in about one in 5000 women who take the drug. The acute and subacute reactions are thought to be due to a hypersensitivity reaction and often resolve when the drug is discontinued. The pulmonary toxicity caused by nitrofurantoin can be categorized into acute, subacute, and chronic pulmonary reactions. These include pulmonary reactions, hepatotoxicity, and neuropathy. Some of the more serious but rare side effects of nitrofurantoin have been a cause of concern. Patients should be informed that nitrofurantoin colours urine brown this is completely harmless.