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Macrobid Side Effects

Generic name: nitrofurantoin

Medically reviewed by Last updated on May 22, 2023.

Note: This document contains side effect information about nitrofurantoin. Some dosage forms listed on this page may not apply to the brand name Macrobid.

Applies to nitrofurantoin: oral capsule, oral suspension.

Serious side effects of Macrobid

Along with its needed effects, nitrofurantoin (the active ingredient contained in Macrobid) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking nitrofurantoin:

More common

Less common


Other side effects of Macrobid

Some side effects of nitrofurantoin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Incidence not known

For Healthcare Professionals

Applies to nitrofurantoin: compounding powder, oral capsule, oral suspension.


Nausea, emesis, and anorexia occurred most often; abdominal pain and diarrhea were less common. These side effects were dose-related and have been minimized by dose reduction. Many patients who could not tolerate the microcrystalline formulation were able to take the macrocrystals formulation without nausea.

The onset of pseudomembranous colitis symptoms has been reported during or after antimicrobial therapy.[Ref]

Common (1% to 10%): Nausea, emesis, flatulence

Uncommon (0.1% to 1%): Abdominal pain, diarrhea

Frequency not reported: Dyspepsia, constipation, sialadenitis, pancreatitis, pseudomembranous colitis, Clostridioides difficile-associated diarrhea, parotitis[Ref]


Common (1% to 10%): Anorexia

Frequency not reported: Acute porphyria, false positive urinary glucose[Ref]

Nervous system

Common (1% to 10%): Headache

Rare (0.01% to 0.1%): Peripheral neuropathy including optic neuritis (sensory and motor involvement), nystagmus, vertigo, dizziness, drowsiness

Frequency not reported: Benign intracranial hypertension (pseudotumor cerebri), bulging fontanels, polyneuropathy (including optic neuritis), sensory loss, paresthesia, motor loss, neuropathy (generally beginning as paresthesia of the lower extremities and the hands and progressing to muscle weakness and wasting), cerebellar dysfunction

Postmarketing reports: Optic neuritis[Ref]

Peripheral neuropathy (which was sometimes severe or irreversible) has occurred; fatalities have been reported. Risk of peripheral neuropathy has been increased with renal dysfunction (CrCl less than 60 mL/min or clinically significant elevated serum creatinine), anemia, vitamin B deficiency, diabetes mellitus, electrolyte imbalance, and debilitating disease.

Polyneuropathy, which started peripherally with initial sensory loss and paresthesia but progressed to motor loss (often with severe muscle atrophy), has occurred during therapy. A predisposing condition in most of these patients was renal failure, which was often accompanied by anemia, diabetes, electrolyte imbalance, vitamin B deficiency, and debilitating disease. After stopping this drug, further deterioration generally halted and total or partial regression occurred in almost 80% of affected patients. These reactions were sometime severe or irreversible but were rarely fatal.[Ref]


Common (1% to 10%): Eosinophilia, decreased hemoglobin

Rare (0.01% to 0.1%): Aplastic anemia

Frequency not reported: Hemolytic anemia, leukopenia, agranulocytosis, granulocytopenia, megaloblastic anemia, glucose-6-phosphate dehydrogenase deficiency anemia, thrombocytopenia, cyanosis secondary to methemoglobinemia[Ref]


Common (1% to 10%): Elevated AST, elevated ALT

Rare (0.01% to 0.1%): Liver failure (may be fatal), cholestatic jaundice, chronic active hepatitis (including fatalities)

Frequency not reported: Hepatic necrosis, autoimmune hepatitis, hepatic reactions (including hepatitis, cholestatic jaundice, chronic active hepatitis, hepatic necrosis), hepatotoxicity with concurrent pulmonary reactions, elevated bilirubin, hepatic toxicity (presented with jaundice, abdominal pain, malaise, nausea, anorexia)[Ref]


Common (1% to 10%): Increased serum phosphorus/phosphate

Frequency not reported: Fever, chills, malaise, asthenia, drug fever, superinfections due to resistant organisms (e.g., Pseudomonas species, Candida species), C difficile superinfections, increased alkaline phosphatase, increased lactate dehydrogenase[Ref]


Chronic pulmonary reactions occurred rarely, generally in patients who received continuous therapy for at least 6 months; such reactions were more common in elderly patients.

Acute pulmonary reactions generally occurred within the first week of therapy and were reversible when therapy was stopped; resolution was often dramatic. Acute pulmonary reactions were commonly manifested by fever, chills, cough, chest pain, dyspnea, pulmonary infiltration with consolidation/pleural effusion on chest x-ray, and eosinophilia.

In subacute pulmonary reactions, fever and eosinophilia occurred less often than in the acute form. After therapy was stopped, recovery sometimes required several months.[Ref]

Rare (0.01% to 0.1%): Chronic pulmonary reactions (symptoms included malaise, exertional dyspnea, cough, altered pulmonary function, radiologic/histologic findings of diffuse interstitial pneumonitis and/or fibrosis)

Frequency not reported: Acute pulmonary reactions (symptoms included fever, chills, cough, chest pain, dyspnea, pulmonary infiltration with consolidation/pleural effusion on chest x-ray, eosinophilia), subacute pulmonary reactions, chronic/subacute/acute pulmonary hypersensitivity reactions, cough, dyspnea, permanent impairment of pulmonary function, pulmonary fibrosis, bronchiolitis obliterans organizing pneumonia, asthma attacks (in patients with history of asthma), pulmonary infiltration with consolidation/pleural effusion on x-ray[Ref]


Rare (0.01% to 0.1%): Collapse, cyanosis, changes in ECG (e.g., nonspecific ST/T wave changes, bundle branch block)

Frequency not reported: Vasculitis, cardiopulmonary failure (leading to collapse and death), chest pain[Ref]

Changes in ECG (e.g., nonspecific ST/T wave changes, bundle branch block) have occurred, associated with pulmonary reactions; vasculitis was sometimes associated with pulmonary reactions.[Ref]


Rare (0.01% to 0.1%): Exfoliative dermatitis, erythema multiforme (including Stevens-Johnson syndrome)

Frequency not reported: Pruritus, urticaria, allergic skin reactions, alopecia/transient alopecia, angioedema/angioneurotic edema, cutaneous vasculitis, maculopapular eruptions, erythematous eruptions, eczematous eruptions, rash, drug rash with eosinophilia and systemic symptoms (DRESS) syndrome[Ref]


Rare (0.01% to 0.1%): Depression, euphoria, confusion, psychotic reactions[Ref]


Frequency not reported: Anaphylaxis

Postmarketing reports: Hypersensitivity reactions[Ref]

Hypersensitivity reactions were the most frequently reported side effect during postmarketing experience.[Ref]


Frequency not reported: Lupus-like syndrome/lupus erythematous-like syndrome, arthralgia, myalgia, muscle atrophy, increased creatine phosphokinase

Lupus-like syndrome has been associated with pulmonary reaction.


Frequency not reported: Interstitial nephritis[Ref]


Frequency not reported: Yellow or brown discoloration of urine, genitourinary tract superinfections (by fungi or resistant organisms [e.g., Pseudomonas, Candida]), dark colored urine[Ref]


Frequency not reported: Amblyopia, retinopathy (due to intraretinal crystals), diplopia[Ref]

Frequently asked questions


1. Product Information. Macrobid (nitrofurantoin). Procter and Gamble Pharmaceuticals. 2002;PROD.

2. Product Information. Macrodantin (nitrofurantoin). Procter and Gamble Pharmaceuticals. 2002;PROD.

3. Cerner Multum, Inc. UK Summary of Product Characteristics.

4. Cerner Multum, Inc. Australian Product Information.

5. Product Information. Nitrofurantoin (nitrofurantoin). AA Pharma Inc. 2016.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.