Furadantin (Nitrofurantoin) - Oral

What Is Nitrofurantoin?

Nitrofurantoin is an oral antibiotic used to treat urinary tract infections (UTIs), which is a type of bladder infection. It works by killing the bacteria that cause the infection.

Nitrofurantoin is available as oral capsules and an oral solution if you have trouble swallowing pills. Nitrofurantoin is a prescription medication, so you’ll need to visit your healthcare provider to see if this treatment is right for you.

Nitrofurantoin is available under the brand names Furadantin, Macrobid, and Macrodantin,

Drug Facts

Generic Name: Nitrofurantoin

Brand Name(s): Furadantin, Macrobid, Macrodantin

Drug Availability: Prescription

Administration Route: Oral

Therapeutic Classification: 

Available Generically: 

Controlled Substance: 

Active Ingredient: Nitrofurantoin

Dosage Form(s): Capsule, suspension (liquid)

What Is Nitrofurantoin Used For?

The Food and Drug Administration (FDA) approved nitrofurantoin to treat bladder infections—a common type of UTI. Bladder infections can cause pain while urinating and make it feel like you need to urinate often and urgently.

Healthcare providers also prescribe nitrofurantoin to prevent UTIs in people with a history of frequent bladder infections.

Furadantin, Macrodantin (Nitrofurantoin) Drug Information: A body showing a bladder

Verywell / Dennis Madamba

How to Take Nitrofurantoin

Nitrofurantoin is usually taken two to four times per day to treat a UTI. If your healthcare provider has prescribed nitrofurantoin to prevent UTIs, they may recommend taking it once daily or only after having sex.

It’s best to take your dose with food, which helps your body absorb the drug and may help prevent certain side effects like nausea. If your healthcare provider has prescribed the oral solution form, be sure to shake the bottle well before measuring your dose.

Be sure to take nitrofurantoin for the number of days prescribed, even if you begin to feel better before then.

Storage

Store nitrofurantoin at room temperature (between 68 and 77 degrees F). Keep the oral solution in its original bottle and protect it from light. Throw away any unused oral solution after 30 days. Keep nitrofurantoin and all your medicines in a safe location, out of reach of children and pets.

How Long Does Nitrofurantoin Take to Work?

Nitrofurantoin usually takes five to seven days to treat a UTI. You may begin to feel better before then, but you should continue taking nitrofurantoin for the number of days prescribed.

What Are the Side Effects of Nitrofurantoin?

This is not a complete list of side effects and others may occur. A healthcare provider can advise you on side effects. If you experience other effects, contact your healthcare provider. You may report side effects to the FDA at fda.gov/medwatch or 1-800-FDA-1088.

Common Side Effects

Some people may experience side effects while taking nitrofurantoin. Some common reactions to watch out for include:

  • Brown-colored urine 
  • Headache
  • Loss of appetite  
  • Nausea or vomiting

Severe Side Effects

Rarely, nitrofurantoin may cause serious side effects. Let your healthcare provider know right away if you develop any serious symptoms. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following.

Lung Problems

Serious and even deadly lung problems have rarely occurred with nitrofurantoin, usually when taken for six months or longer. Let your healthcare provider know right away if you experience:

  • Fever
  • Chills
  • Chest pain
  • Cough
  • Trouble breathing

Liver Problems

Nitrofurantoin may affect the liver, and serious and sometimes deadly reactions have happened. Contact your healthcare provider if you develop the following symptoms:

  • Dark urine
  • Tiredness
  • Loss of appetite
  • Upset stomach or stomach pain
  • Light-colored stools
  • Vomiting
  • Yellow skin or eyes

Nerve Problems

Nitrofurantoin can rarely cause a condition called peripheral neuropathy, which damages your nerves. Some people have developed severe symptoms which led to death. Let your healthcare provider know right away if you have numbness, burning, or a tingling feeling. 

C. Diff Infection

Nitrofurantoin may cause a severe form of diarrhea called Clostridioides difficile-associated diarrhea, or C. diff for short. This can sometimes lead to deadly complications. C. diff may occur during treatment or a few months after stopping nitrofurantoin. Let your healthcare provider know if you develop stomach pain, cramps, or very loose, watery, or bloody stools.

Be sure to check with your healthcare provider before treating diarrhea with over-the-counter (OTC) medications—this can lead to serious problems if your diarrhea is caused by C. diff

Allergic Reaction

Watch out for signs of an allergic reaction, including:

  • Rash
  • Hives
  • Itching
  • Wheezing
  • Trouble breathing
  • Swelling of the mouth, face, lips, tongue, or throat.

Reactions can sometimes be severe, so seek medical attention right away if you develop symptoms.

Long-Term Side Effects

Nitrofurantoin can sometimes cause long-term problems, even after you’ve stopped treatment. Lung and nerve damage can be permanent. Let your healthcare provider know if you experience any of the above symptoms related to these conditions right away.

Report Side Effects

Nitrofurantoin may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your healthcare provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Nitrofurantoin Should I Take?

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The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For oral dosage forms (capsules, suspension, and tablets):
    • For prevention of urinary tract infections:
      • Adults and teenagers—50 to 100 milligrams (mg) at bedtime.
      • Children and infants 1 month of age and older—Dose is based on body weight and must be determined by your doctor.
      • Infants younger than 1 month of age—Use is not recommended.
    • For treatment of urinary tract infections:
      • Adults and teenagers—50 to 100 milligrams (mg) every six hours.
      • Children and infants 1 month of age and older—Dose is based on body weight and must be determined by your doctor.
      • Infants younger than 1 month of age—Use is not recommended.
  • For oral dosage form (extended-release capsules):
    • For treatment of urinary tract infections:
      • Adults, teenagers, and children 12 years of age and older—100 milligrams (mg) every twelve hours for seven days.
      • Children younger than 12 years of age—Use and dose must be determined by your doctor.

Modifications

For children, dosing may be dependent on weight. Your child's healthcare provider will let you know how much they should be taking.

There are no adequate studies of nitrofurantoin use during pregnancy, so it is recommended to only use nitrofurantoin if necessary. While seeking treatment, tell your healthcare provider if you are pregnant, which may influence which medication they prescribe.

Missed Dose

If you forget a dose of nitrofurantoin, take it as soon as you remember. If it’s almost time for your next dose, skip the missed dose. Do not double up or take extra to make up for the missed dose.

Overdose: What Happens If I Take Too Much Nitrofurantoin?

If you’ve taken too much nitrofurantoin, the most likely effect will be nausea and vomiting. Call your healthcare provider or the Poison Control center if you think you’ve overdosed on nitrofurantoin. If your symptoms feel life-threatening, call 911.

What Happens If I Overdose on Nitrofurantoin?

If you think you or someone else may have overdosed on nitrofurantoin, call a healthcare provider or the Poison Control Center (800-222-1222).

If someone collapses or isn't breathing after taking nitrofurantoin, call 911 immediately.

Precautions

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If you or your child will be taking this medicine for a long time, it is very important that your doctor check you at regular visits for any problems or unwanted effects that may be caused by this medicine.

If you or your child's symptoms do not improve within a few days, or if they become worse, check with your doctor.

Diabetic patients that use urine sugar tests should be careful when using this medicine. Nitrofurantoin may cause false test results with some urine sugar tests. Check with your doctor before changing your diet or the dose of your diabetes medicine.

Liver problems may occur while you are using this medicine. Stop using this medicine and check with your doctor right away if you are having more than one of these symptoms: stomach pain or tenderness; clay-colored stools; dark urine; decreased appetite; fever; headache; itching; loss of appetite; nausea and vomiting; skin rash; swelling of the feet or lower legs; unusual tiredness or weakness; or yellow eyes or skin.

Tell your doctor right away if you start having numbness, tingling, or burning pain in your hands, arms, legs, or feet. These may be symptoms of a condition called peripheral neuropathy.

Nitrofurantoin may cause diarrhea, and in some cases it can be severe. Do not take any medicine to treat diarrhea without first checking with your doctor. Diarrhea medicines may make the diarrhea worse or make it last longer. If you have any questions about this, or if mild diarrhea continues or gets worse, check with your doctor.

This medicine may cause the urine to become a rust-yellow to brown color. This side effect does not require medical attention.

What Are Reasons I Shouldn’t Take Nitrofurantoin?

Certain conditions increase your risk of developing complications from nitrofurantoin. Nitrofurantoin should not be used if you:

  • Are more than 38 weeks pregnant 
  • Have an allergy to nitrofurantoin 
  • Have experienced liver problems from nitrofurantoin in the past 
  • Have significant kidney problems or trouble passing urine
  • Are breastfeeding

Nitrofurantoin should not be used in infants less than 1-month-old as it can cause serious blood problems.

What Other Medications Interact With Nitrofurantoin?

Other medications you take may interact with nitrofurantoin. Let your healthcare provider know about all the medicines you take, including non-prescription products.

Avoid taking nitrofurantoin with:

  • Antacids that contain magnesium trisilicate: Magnesium trisilicate can decrease the effectiveness of nitrofurantoin. 
  • Probenecid (a gout medication): Probenecid can increase levels of nitrofurantoin in the blood and lead to side effects. Probenecid can also lower levels of nitrofurantoin in the bladder and prevent it from working. 
  • Sodium picosulfate (found in Clenpiq—a product used for bowel cleansing before a colonoscopy): Nitrofurantoin can decrease the effectiveness of Clenpiq. 

This is not a complete list of all the medications that may interact with nitrofurantoin. Always ask your healthcare provider or pharmacist before starting anything new.

What Medications Are Similar?

Nitrofurantoin is a common choice for treating UTIs since it’s highly effective. However, your healthcare provider may choose a different antibiotic based on your allergies, recent antibiotics you’ve taken, cost, and availability. Other options include:

  • Bactrim (trimethoprim-sulfamethoxazole)
  • Monurol (fosfomycin)

This is a list of drugs also prescribed to treat UTIs. It is NOT a list of drugs recommended to take with nitrofurantoin. You should not take these drugs together. Ask your healthcare provider or pharmacist if you have any questions about your medications.

Frequently Asked Questions

  • What is nitrofurantoin used for?

    Nitrofurantoin is used to treat bladder infections—a common type of urinary tract infection or UTI. Nitrofurantoin can also be used to prevent UTIs if you experience frequent infections.

  • How does nitrofurantoin work?

    Nitrofurantoin is an antibiotic. It works by killing the bacteria causing the bladder infection.

  • How long does it take for nitrofurantoin to work?

    Nitrofurantoin usually takes five to seven days to treat a bladder infection. It is important to finish your prescription for the number of days your healthcare provider has prescribed, even if you begin to feel better before then.

  • What are the side effects of nitrofurantoin?

    The most common side effects of nitrofurantoin include nausea, vomiting, loss of appetite, headache, and brown-colored urine.

How Can I Stay Healthy While Taking Nitrofurantoin?

UTIs can be a real pain—especially if you suffer from frequent infections. Fortunately, antibiotics like nitrofurantoin can treat the infection and get you feeling back to normal. Nitrofurantoin is a highly effective medication; most people can take it without any issues. 

Along with your prescribed treatment, there are additional ways to boost your recovery while coping with a UTI:

  • Stay hydrated: Drinking at least eight glasses of water a day is recommended.
  • Try to urinate more frequently: Emptying your bladder as much as possible can help your body eliminate the infection.
  • Use a heating pad or take a warm bath: UTIs can cause uncomfortable symptoms, such as pain and pressure in your bladder.

Rarely, nitrofurantoin can cause serious side effects, especially the longer you take it. Pay attention to your body and let your healthcare provider know immediately if you notice anything that doesn’t seem right. Identifying symptoms of an adverse reaction and stopping the medication can help keep you healthy.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended to replace medical advice, diagnosis, or treatment from a healthcare provider. Consult your healthcare provider before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. DailyMed. Label: Furadantin- nitrofurantoin suspension.

  2. DailyMed. Nitrofurantoin - nitrofurantoin capsule.

  3. Kolman KB. Cystitis and pyelonephritis: diagnosis, treatment, and prevention. Prim Care. 2019;46(2):191-202. doi:10.1016/j.pop.2019.01.001

By Christina Varvatsis, PharmD
Christina Varvatsis is a hospital pharmacist and freelance medical writer. She is passionate about helping individuals make informed healthcare choices by understanding the benefits and risks of their treatment options.