Nitrofurantoin (Macrobid) Side Effects
Macrobid (nitrofurantoin) adverse effects range from common gastrointestinal and neurologic symptoms to rare but serious pulmonary, hepatic, and neurologic toxicities. [1] The most clinically important serious adverse reactions are acute/subacute pulmonary hypersensitivity reactions, chronic pulmonary toxicity with long-term use, hepatotoxicity, and peripheral neuropathy. [1]
Common (Often Mild) Adverse Effects
The most frequent clinical adverse events reported as possibly or probably drug-related were nausea (8%), headache (6%), and flatulence (1.5%). [1]
Hypersensitivity and Pulmonary Reactions
Acute pulmonary hypersensitivity reactions can occur and require discontinuation of nitrofurantoin when suspected. [1] Allergic pulmonary reactions include lupus-like syndrome associated with nitrofurantoin. [2] Chronic pulmonary reactions have been observed, particularly with longer-term treatment. [1]
Hepatotoxicity
Hepatotoxicity can occur with nitrofurantoin and can range from mild laboratory abnormalities to severe liver injury. [1] Nitrofurantoin is a recognized cause of drug-induced liver injury, including acute or chronic hepatitis-like syndromes. [3]
Peripheral Neuropathy
Peripheral neuropathy is a serious adverse effect associated with nitrofurantoin, with increased risk in patients with contributing conditions such as renal impairment and debilitating disease. [1] Peripheral neuropathy risk is increased by impaired renal function (creatinine clearance below 60 mL/min or clinically significant elevated serum creatinine). [1]
Other Notable Adverse Effects
Laboratory adverse events reported in Macrobid clinical trials (1% to 5%, without regard to drug relationship) included eosinophilia, increased AST (SGOT), increased ALT (SGPT), decreased hemoglobin, and increased serum phosphorus. [2] Hypersensitivity reactions represent the most frequent spontaneously reported adverse events in postmarketing experience with nitrofurantoin formulations. [2]
Urgent Actions for Severe Reactions
Macrobid should be discontinued if acute pulmonary reactions occur because appropriate measures and evaluation are required. [1] Medical evaluation is required for symptoms suggestive of pulmonary toxicity (new or worsening shortness of breath, cough, or systemic symptoms), hepatotoxicity (e.g., jaundice or dark urine), or neuropathy (numbness or tingling). [1]