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Nitrofurantoin Side Effects

For the Consumer

Applies to nitrofurantoin: oral capsule, oral suspension, oral tablet

As well as its needed effects, nitrofurantoin may cause unwanted side effects that require medical attention.

Severity: Major

If any of the following side effects occur while taking nitrofurantoin, check with your doctor immediately:

More common:
  • Changes in facial skin color
  • chest pain
  • chills
  • cough
  • fever
  • general feeling of discomfort or illness
  • hives
  • hoarseness
  • itching
  • joint or muscle pain
  • shortness of breath
  • skin rash
  • sudden trouble in swallowing or breathing
  • swelling of the face, mouth, hands, or feet
  • troubled breathing
Less common:
  • Black, tarry stools
  • blood in the urine or stools
  • burning, numbness, tingling, or painful sensations
  • dizziness
  • drowsiness
  • headache
  • pinpoint red spots on the skin
  • sore throat
  • unsteadiness or awkwardness
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • weakness in the arms, hands, legs, or feet
  • Abdominal or stomach pain
  • blindness
  • blistering, peeling, or loosening of the skin and mucous membranes
  • blue-yellow color blindness
  • bluish color of the fingernails, lips, skin, palms, or nail beds
  • blurred vision or loss of vision, with or without eye pain
  • bulging soft spot on the head of an infant
  • change in the ability to see colors, especially blue or yellow
  • confusion
  • cracks in the skin
  • darkening of the urine
  • decreased vision
  • diarrhea
  • diarrhea, watery and severe, which may also be bloody
  • eye pain
  • general tiredness and weakness
  • light-colored stools
  • loss of appetite
  • loss of heat from the body
  • mental depression
  • mood or mental changes
  • nausea or vomiting
  • pale skin
  • pale stools
  • red skin lesions, often with a purple center
  • red, irritated eyes
  • red, swollen skin
  • red, thickened, or scaly skin
  • skin rash
  • sores, ulcers, or white spots on the lips or in the mouth
  • swollen or painful glands
  • tenderness of salivary glands
  • unpleasant breath odor
  • upper right abdominal pain
  • visual changes
  • vomiting of blood
  • wheezing or tightness in the chest
  • yellow eyes or skin

Severity: Minor

Some nitrofurantoin side effects may not need any medical attention. As your body gets used to the medicine these side effects may disappear. Your health care professional may be able to help you prevent or reduce these side effects, but do check with them if any of the following side effects continue, or if you are concerned about them:

More common:
  • Diarrhea
  • gas
Incidence not known:
  • Dizziness or lightheadedness
  • feeling of constant movement of self or surroundings
  • lack or loss of strength
  • loss of hair, temporary
  • sensation of spinning
  • uncontrolled eye movements

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 (minimized by dose reduction) and occurred more frequently with Furadantin(R), the crystalline form of the drug. Administration of the drug with food reduced gastrointestinal intolerance.

Comparative studies of the gastrointestinal side effects of the crystalline form (Furadantin[R]) and the macrocrystalline form (Macrodantin[R]) reported up to 34% gastrointestinal intolerance with the crystalline form and up to 13% with the macrocrystalline form. In patients who were unable to tolerate Furadantin(R), 80% were able to tolerate Macrodantin(R).

The onset of pseudomembranous colitis symptoms has been reported during and after antimicrobial therapy.

Pancreatitis due to nitrofurantoin has been reported. In one case, the patient experienced cholestatic jaundice secondary to edema of the pancreas.

Common (1% to 10%): Nausea (8%), flatulence (1.5%)
Uncommon (0.1% to 1%): Diarrhea (less than 1%), dyspepsia (less than 1%), abdominal pain (less than 1%), constipation (less than 1%), emesis (less than 1%)
Rare (less than 0.1%): Parotitis, pseudomembranous colitis
Frequency not reported: Anorexia, sialadenitis, pancreatitis


Uncommon (0.1% to 1%): Acute pulmonary hypersensitivity reaction (less than 1%)
Rare (less than 0.1%): Cyanosis
Frequency not reported: Pulmonary hypersensitivity reactions (chronic and subacute), chronic pulmonary reactions (symptoms include malaise, exertional dyspnea, cough, altered pulmonary function, radiologic/histologic findings of diffuse interstitial pneumonitis and/or fibrosis), acute pulmonary reactions (symptoms include fever, chills, cough, chest pain, dyspnea, pulmonary infiltration with consolidation or pleural effusion on x-ray, eosinophilia), pulmonary toxicity (acute and chronic), alveolar infiltrates, alveolar hemorrhage (including fatal cases), interstitial fibrosis, pneumonitis, drug-induced bronchiolitis obliterans with organizing pneumonia

Respiratory system side effects have included both acute and chronic pulmonary toxicity. Acute toxicity has occurred from within a few hours to 3 weeks after therapy was started and consisted of dyspnea, cough, fever, and chills. Chronic toxicity has generally occurred after 6 months of therapy and has presented with an insidious onset of dyspnea, cough, malaise, and fatigue.

Respiratory side effects associated with nitrofurantoin therapy have occurred as both acute and chronic events. Acute pulmonary reactions have manifested as a type of hypersensitivity, and have occurred rapidly in patients who were previously sensitized. Of one group of 447 pulmonary reactions reported, 89% were of the acute type. Patients commonly had eosinophilia. Lung changes generally included alveolar infiltrates. Alveolar hemorrhage and death have been reported. Symptoms generally resolved within 24 to 48 hours after nitrofurantoin was discontinued.

Chronic pulmonary reactions occurred after 6 months of therapy and were generally more severe. Biopsy often revealed interstitial fibrosis. Eosinophilia was less common. Positive antinuclear antibodies were reported in up to 66% of patients, and patients commonly exhibited abnormal liver function tests. Resolution of symptoms usually occurred over a few months, although deaths have been reported. It has been suggested that the mechanism of this reaction is a combination of drug toxicity and an immune reaction.


Frequency not reported: Changes in EKG (e.g., nonspecific ST/T wave changes, bundle branch block) associated with pulmonary reactions


Rare (less than 0.1%): Hepatic reactions (including hepatitis, cholestatic jaundice, chronic active hepatitis, hepatic necrosis), hepatotoxicity with concurrent pulmonary reactions
Frequency not reported: Elevated AST (SGOT), elevated ALT (SGPT), elevated bilirubin, hepatic toxicity (presented with jaundice, abdominal pain, malaise, nausea, and anorexia)

Fatalities have been reported with hepatic reactions.

Hepatic toxicity has occurred more often following lengthy therapy (6 months or more) and has presented with jaundice, abdominal pain, malaise, nausea, and anorexia.

Most acute hepatic reactions were self-limiting and resolved within a few days. Patients who experienced chronic reactions often had positive antinuclear antibodies (77%) and may have developed chronic active hepatitis or hepatic necrosis. Liver function tests generally returned to normal after a few months, although deaths due to hepatic failure have been reported.

Hepatotoxicity with concurrent pulmonary effects following the use of nitrofurantoin has been reported and may be mediated by the immune system. A case of hepatotoxicity accompanied by elevations in serum immune globulins (IgG) has been reported. The authors theorized that cytotoxic T cells (CD8) were involved in the liver damage. They postulated that the antigen-antibody complex was removed when the drug was discontinued as evidenced by the patient's rapidly corrected liver enzyme levels.

Nervous system

Common (1% to 10%): Headache (6%)
Uncommon (0.1% to 1%): Dizziness (less than 1%), drowsiness (less than 1%)
Rare (less than 0.1%):Vertigo, benign intracranial hypertension (pseudotumor cerebri), bulging fontanels
Frequency not reported: Peripheral neuropathy, vertigo, neuropathy (generally beginning as paresthesia of the lower extremities and the hands and progressing to muscle weakness and wasting), cerebellar dysfunction

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

Peripheral neuropathy has developed after a few days to several months of therapy. There was no consistent relationship between the dose, length of therapy, and neuropathy development. In a review of 100 cases of peripheral neuropathy, 34 experienced total regression, 45 had partial regression, 13 had no change, and 8 died.


Rare (less than 0.1%): Cyanosis secondary to methemoglobinemia, aplastic anemia
Frequency not reported: Hemolytic anemia, leukopenia, agranulocytosis, granulocytopenia, megaloblastic anemia, eosinophilia, decreased hemoglobin, glucose-6-phosphate dehydrogenase deficiency anemia, thrombocytopenia


Uncommon (0.1% to 1%): Pruritus (less than 1%), urticaria (less than 1%)
Frequency not reported: Lupus-like syndrome associated with pulmonary reactions, angioedema, eruptions (maculopapular, erythematous, and eczematous), anaphylaxis, arthralgia, myalgia, drug fever, chills, vasculitis (sometimes associated with pulmonary reactions)
Postmarketing reports: Hypersensitivity reactions

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


Uncommon (0.1% to 1%): Alopecia (less than 1%)
Rare (less than 0.1%): Exfoliative dermatitis, erythema multiforme (including Stevens-Johnson syndrome)
Frequency not reported: Transient alopecia


Uncommon (0.1% to 1%): Amblyopia (less than 1%)
Rare (less than 0.1%): Retinopathy due to intraretinal crystals (at least 1 case)
Frequency not reported: Diplopia, nystagmus
Postmarketing reports: Optic neuritis (rare)

Retinopathy due to intraretinal crystals has been reported in a patient with a 9-year history of nitrofurantoin use.


Uncommon (0.1% to 1%): Fever (less than 1%), chills (less than 1%), malaise (less than 1%)
Rare (less than 0.1%): Systemic lupus erythematous-like reactions
Frequency not reported: Asthenia, superinfections due to resistant organisms


Rare (less than 0.1%): Acute interstitial nephritis


Rare (less than 0.1%): Confusion, depression, psychotic reactions


Frequency not reported: Increased serum phosphorus, increased alkaline phosphatase, increased lactate dehydrogenase, increased creatine phosphokinase


Frequency not reported: Dark discoloration of urine

It is possible that some side effects of nitrofurantoin may not have been reported. These can be reported to the FDA here. Always consult a healthcare professional for medical advice.

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.