Medically Reviewed on 8/20/2022

Generic Name: nitrofurantoin

Brand Names: Macrodantin, Furadantin, Macrobid

Drug Class: Antibiotics, Other

What is nitrofurantoin, and what is it used for?

Nitrofurantoin is an antibiotic that is used for treating urinary tract infections caused by several types of bacteria. It is effective against E. Coli, Enterobacter cystitis, Enterococcus, Klebsiella, and Staphylococcus aureus. Nitrofurantoin interferes with the production of bacterial proteins, DNA, and cell walls. Bacteria cannot survive without a cell wall or multiply without DNA.

Three forms of nitrofurnatoin are available:

  • Furadantin, a microcrystalline form,
  • Macrodantin, a macrocrystalline, and
  • Macrobid, a sustained release form of macrocrystalline used twice daily.

The macrocrystalline form is more slowly absorbed than the microcrystalline form and is useful for patients who cannot tolerate the microcrystalline form.

What are the side effects of nitrofurantoin?

  • Common side effects of nitrofurantoin include:
  • The macrocrystalline form (Macrodantin) appears to cause less stomach upset. Stomach upset also can be minimized by using a lower dose or by taking nitrofurantoin with food or milk.
  • Possible serious side effects include:
  • Nitrofurantoin can cause serious lung injury. The reaction can occur within hours of the start of treatment if the patient has previously received nitrofurantoin, or within a few days of starting nitrofurantoin for the first time. Symptoms include:
  • In other persons, lung injury may occur after approximately a month of treatment. Symptoms include:
    • Difficulty breathing
    • Rapid breathing
    • Cough
  • Fortunately, the symptoms usually resolve within a week if the medication is stopped. In other individuals, lung injury may not develop until after several months or years of therapy. Unless it is recognized and treated, this delayed lung injury can result in permanent lung damage that remains even after the drug is stopped.
  • Nitrofurantoin can also cause damage to the sensory nerves of the arms and legs (peripheral neuropathy), which can cause tingling in the extremities. The condition can become severe and is more likely to occur in people with diabetes, vitamin B deficiency, or general debilitation.
  • Reduced red blood cell count (anemia) by breaking red blood cells (hemolytic anemia) can occur from nitrofurantoin. This reaction occurs most frequently in persons with a deficiency of an enzyme called glucose--6-phosphate dehydrogenase that is very important to the survival of red blood cells.
  • Nitrofurantoin also can cause liver damage leading to jaundice or a form of hepatitis that can be fatal. Elevated liver enzymes indicate liver damage and are a reason to stop the drug.
  • Treatment with nitrofurantoin can cause urine to change color to a dark yellow or brown.


How much urine does the average adult pass each day? See Answer

What is the dosage for nitrofurantoin?

  • The recommended adult dose for treating urinary tract infections is 50-100 mg 4 times daily (Macrodantin, Furadantin) or 100 mg every 12 hours (Macrobid) for 7 days or for 3 days after obtaining sterile urine.
  • Nitrofurantoin can be taken with or without meals. Taking it with meals increases its absorption into the body.
  • The suspension can be mixed with water, milk, juice, or infant formula.
  • It also is used once a day (or in some children, twice daily) to prevent urinary tract infections.
  • It should not be used in persons with poor kidney function.

Which drugs interact with nitrofurantoin?

  • High doses of probenecid (Benemid) or sulfinpyrazone (Anturane) can partially block the kidneys' elimination of nitrofurantoin. This can increase the blood concentrations of nitrofurantoin and the risk of toxicity from nitrofurantoin.
  • Concomitant administration of a magnesium trisilicate antacid may decrease the absorption of nitrofurantoin, reducing the effectiveness of nitrofurantoin.
  • Nitrofurantoin may reduce the activity of live tuberculosis vaccine (BCG vaccine) and live typhoid vaccine. In laboratory tests, nitrofurantoin reduced the effect of quinolone antibiotics, for example, norfloxacin (Noroxin). Therefore, nitrofurantoin should not be combined with quinolone antibiotics.

Is nitrofurantoin safe to use during pregnancy or while breastfeeding?

  • Although there are no adequate studies of nitrofurantoin in pregnant women, many women have safely used it during pregnancy. However, nitrofurantoin should not be used near the time of delivery (38-42 weeks gestation) since it interferes with the immature enzyme systems in the red blood cells of newborns, damaging the cells and resulting in anemia.
  • Nitrofurantoin is distributed into breast milk and should be used with caution in women who are breastfeeding.

What else should I know about nitrofurantoin?

Do I need a prescription for nitrofurantoin (Macrobid, Macrodantin, Furadantin)?


What preparations of nitrofurantoin (Macrobid, Macrodantin, Furadantin) are available?
  • Capsules: 25, 50, 75, and 100 mg.
  • Oral suspension: 25 mg/5 ml.
How should I keep nitrofurantoin (Macrobid, Macrodantin, Furadantin) stored?
  • All formulations should be kept at room temperature, 15 C TO 30 C (59 F to 86 F).
When was nitrofurantoin (Macrobid, Macrodantin, Furadantin) approved by the FDA?
  • The FDA approved nitrofurantoin in 1953.


Nitrofurantoin is a drug available in three forms prescribed for the treatment or prevention of urinary tract infections (UTIs). Common side effects include loss of appetite, diarrhea, abdominal pain, vomiting, and rash. Review warnings and precautions, drug interactions, and pregnancy and breastfeeding safety information prior to taking any medication.

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Medically Reviewed on 8/20/2022
Medically reviewed by John P. Cunha, DO, FACOEP; Board Certified Emergency Medicine


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