Nitrofurantoin | Side Effects, Dosage, Uses & More
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Generic Name:

nitrofurantoin, Oral capsule

Generic Name:
Macrobid,Macrodantin

nitrofurantoin, Oral capsule

All Brands

  • Macrobid
  • Macrodantin
SECTION 1 of 5

Highlights for nitrofurantoin

Oral capsule
1

Nitrofurantoin is used to prevent and treat urinary tract infections that are caused by certain bacteria.

2

This drug is available as the brand-named drugs Furadantin, Macrobid, and Macrodantin. It’s also available as a generic drug.

3

This drug comes as a capsule or liquid that you take by mouth.

IMPORTANT INFORMATION

Lung inflammation

This drug may cause lung inflammation. This is a rare side effect and is more likely to happen if you take the drug for longer than 6 months. Symptoms of lung inflammation can include tiredness, fever, chills, cough, chest pain, and shortness of breath. If you have any of these symptoms, contact your doctor right away.

Liver problems

This drug may cause liver inflammation or liver injury. If you’re taking nitrofurantoin for long-term therapy, your doctor will monitor your liver with blood tests. Tell your doctor if you have symptoms of liver problems while taking this drug. These include itching, yellowing of your skin or the whites of your eyes, nausea, vomiting, dark urine, and loss of appetite.

Nerve damage

This drug may cause nerve damage. This damage can cause numbness and pain, especially in your hands and feet.

Red blood cell damage

This drug may cause hemolysis (a type of red blood cell damage). Symptoms of hemolysis include tiredness, weakness, and pale skin. Hemolysis goes away after you stop taking this drug.

Diarrhea

This drug may cause mild or severe diarrhea. Tell your doctor right away if you have diarrhea while taking this drug. If your diarrhea is mild, it may stop after you stop taking this drug. If your diarrhea is more severe, it may not stop after you stop taking this drug, and you could be at risk of severe dehydration. If you have severe diarrhea, your doctor may give you fluids and treat the bacteria causing your diarrhea with antibiotics.

What is nitrofurantoin?

Nitrofurantoin is a prescription drug. It comes as a capsule or suspension that you take by mouth.

Nitrofurantoin is available as the brand-name drugs Furadantin, Macrobid, and Macrodantin. It’s also available as a generic drug. Generic drugs usually cost less. In some cases, they may not be available in every strength or form as the brand-name versions.

Why it's used

Nitrofurantoin treats and prevents urinary tract infections that are caused by certain types of bacteria.

How it works

Nitrofurantoin belongs to a class of drugs called antimicrobials or antibiotics.

See Details

How it works

Nitrofurantoin belongs to a class of drugs called antimicrobials or antibiotics. A class of drugs is a group of medications that work in a similar way. These drugs are often used to treat similar conditions.

Nitrofurantoin helps kill the bacteria that cause urinary tract infections. It only works against certain types of bacteria.

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SECTION 2 of 5

nitrofurantoin Side Effects

Oral capsule

More common side effects

The more common side effects of nitrofurantoin can include:

  • nausea

  • vomiting

  • loss of appetite

  • stomach pain

  • diarrhea

  • dumbness in your hands and feet

  • pain in your hands and feet

  • weakness

  • dizziness

  • headache

  • drowsiness

If these effects are mild, they may go away within a few days or a couple of weeks. If they’re more severe or don’t go away, talk to your doctor or pharmacist.

Serious side effects

Call your doctor right away if you have serious side effects. Call 9-1-1 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 inflammation. Symptoms can include:

    • tiredness
    • shortness of breath
    • fever
    • chills
    • cough
    • chest pain
  • Liver problems. Symptoms can include:

    • itching
    • yellowing of your skin or the whites of your eyes
    • nausea or vomiting
    • dark urine
    • loss of appetite
  • Nerve damage. Symptoms can include:

    • numbness or tingling in your hands and feet
    • muscle weakness
  • Hemolysis (red blood cell damage). Symptoms can include:

    • tiredness
    • weakness
    • pale skin
Pharmacist's Advice
Healthline Pharmacist Editorial Team

Nitrofurantoin may cause drowsiness.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this information includes all possible side effects. This information is not a substitute for medical advice. Always discuss possible side effects with a healthcare provider who knows your medical history.
SECTION 3 of 5

nitrofurantoin May Interact with Other Medications

Oral capsule

Nitrofurantoin can interact with other medications, vitamins, or herbs you may be taking. An interaction is when a substance changes the way a drug works. This can be harmful or prevent the drug from working well.

To help avoid interactions, your doctor should manage all of your medications carefully. Be sure to tell your doctor about all medications, vitamins, or herbs you’re taking. To find out how this drug might interact with something else you’re taking, talk to your doctor or pharmacist.

Medications that might interact with this drug

Drugs you should not use with nitrofurantoin

Do not take these drugs with nitrofurantoin. Doing so can cause dangerous effects in your body. Examples of these drugs include:

  • Antacids such as Gaviscon that contain magnesium trisilicate
    • These drugs can make nitrofurantoin less effective.
  • Probenecid and sulfinpyrazone
    • Taking these drugs while you’re taking nitrofurantoin may cause harmful levels of nitrofurantoin to build up in your blood. High levels of this drug in your body raise your risk of side effects. It also makes the drug less effective.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs interact differently in each person, we cannot guarantee that this information includes all possible interactions. This information is not a substitute for medical advice. Always speak with your healthcare provider about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.
Drug warnings
kidney disease warning
People with kidney disease

If you have a history of kidney disease, you may not be able to clear nitrofurantoin from your body well. This could lead to a buildup of nitrofurantoin. This raises your risk of side effects.

liver disease warning
People with liver disease

You should not use nitrofurantoin. It can make your liver damage worse.

pregnancy warning
Pregnant women

During weeks 0–37 of pregnancy, nitrofurantoin is a category B pregnancy drug. That means two things:

  1. Research in animals has not shown a risk to the fetus when the mother takes the drug.
  2. There aren’t enough studies done in humans to show if the drug poses a risk to the fetus.

Talk to your doctor if you’re pregnant or plan to become pregnant. Animal studies do not always predict the way humans would respond.

Nitrofurantoin can cause red blood cell problems in a newborn. For this reason, women who are pregnant should not take this drug:

  • when they are at term (38–42 weeks of pregnancy),
  • during labor and delivery
  • if they think they are in labor
breast feeding warning
Women who are breast-feeding

Nitrofurantoin may pass into breast milk and cause side effects in a child who is breastfed.

Talk to your doctor about breastfeeding your child. You may need to decide whether to stop breastfeeding or stop taking this medication.

senior warning
For seniors

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects. If you’re older than 65 years, nitrofurantoin may not be a good choice for you.

childrens warning
For children

Do not use any form of nitrofurantoin in infants younger than 1 month.

Furadantin and Macrodantin and their generic forms are safe for use in children older than 1 month.

Macrobid and its generic form have not been studied in children younger than 12 years of age. They should not be used in this age group.

call the doctor
When to call the doctor

Call your doctor if:

  • You become pregnant while taking this drug.
  • You still have symptoms of a urinary tract infection after you finish taking all of your nitrofurantoin. Symptoms of a urinary tract infection can include urgency to urinate, burning during urination, and frequent urination.
allergy warning
Allergies

Nitrofurantoin can cause a severe allergic reaction. Symptoms can include:

  • trouble breathing
  • swelling of your throat or tongue

If you have an allergic reaction, call your doctor or local poison control center right away. If your symptoms are severe, call 9-1-1 or go to the nearest emergency room.

Don’t take this drug again if you’ve ever had an allergic reaction to it. Taking it again could be fatal (cause death).

SECTION 4 of 5

How to Take nitrofurantoin (Dosage)

Oral capsule

All possible dosages and drug forms may not be included here. Your dosage, drug form, and how often you take the drug will depend on:

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

What are you taking this medication for?

Treatment of urinary tract infections

Brand: Nitrofurantoin

Form: oral suspension
Strengths: 25 mg/5 mL

Brand: Nitrofurantoin monohydrate/macrocrystals (generic for Macrobid)

Form: oral capsule
Strengths: 100 mg (75 mg nitrofurantoin monohydrate and 25 mg nitrofurantoin macrocrystals)

Brand: Nitrofurantoin (generic for Macrodantin)

Form: oral capsule
Strengths: 25 mg, 50 mg, 100 mg

Brand: Furadantin

Form:oral suspension
Strengths: 25 mg/5 mL

Brand: Macrobid

Form: oral capsule
Strengths: 100 mg (75 mg nitrofurantoin monohydrate and 25 mg nitrofurantoin macrocrystals)

Brand: Macrodantin

Form: oral capsule
Strengths: 25 mg, 50 mg, 100 mg
Adult dosage (ages 18–64 years)
  • Furadantin, Macrodantin, and the generic drug for each: 50–100 mg four times per day. Length of treatment varies.
  • Macrobid and generic Macrobid: 100 mg every 12 hours for 7 days.
Child dosage (ages 12–17 years)
  • Furadantin, Macrodantin, and the generic drug for each: 5–7 mg/kg of body weight per day in four divided doses. Length of treatment may vary.
  • Macrobid and generic Macrobid: 100 mg every 12 hours for 7 days.
Child dosage (ages 1 month–11 years )
  • Furadantin, Macrodantin, and the generic drug for each: 5–7 mg/kg of body weight per day in 4 divided doses. Length of treatment may vary.
  • Macrobid and generic Macrobid: These drugs have not been studied in children younger than 12 years. They should not be used in this age group.
Child dosage (ages 0–1 month)
  • Furadantin, Macrodantin, and the generic drug for each: These drugs should not be used in children younger than 1 month.
  • Macrobid and generic Macrobid: These drugs have not been studied in children younger than 12 years. They should not be used in this age group.
Senior dosage (ages 65 years and older)

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects.

Your doctor may start you on a lowered dosage or a different treatment schedule. This can help keep levels of this drug from building up too much in your body.

Prevention of urinary tract infections

Brand: Nitrofurantoin

Form: oral suspension
Strengths: 25 mg/5 mL

Brand: Nitrofurantoin monohydrate/macrocrystals (generic for Macrobid)

Form: oral capsule
Strengths: 100 mg (75 mg nitrofurantoin monohydrate and 25 mg nitrofurantoin macrocrystals)

Brand: Nitrofurantoin (generic for Macrodantin)

Form: oral capsule
Strengths: 25 mg, 50 mg, 100 mg

Brand: Furadantin

Form:oral suspension
Strengths: 25 mg/5 mL

Brand: Macrobid

Form: oral capsule
Strengths: 100 mg (75 mg nitrofurantoin monohydrate and 25 mg nitrofurantoin macrocrystals)

Brand: Macrodantin

Form: oral capsule
Strengths: 25 mg, 50 mg, 100 mg
Adult dosage (ages 18–64 years)
  • Furadantin, Macrodantin, and the generic drug for each:50–100 mg at bedtime.
  • Macrobid and generic Macrobid: These drugs are not used for the prevention of urinary tract infections.
Child dosage (ages 1 month–17 years)
  • Furadantin, Macrodantin, and the generic drug for each: 1 mg/kg of body weight once per day or divided into two doses per day.
  • Macrobid and generic Macrobid: These drugs are not used for the prevention of urinary tract infection.
Child dosage (ages 0–1 month)
  • Furadantin, Macrodantin, and the generic drug for each: These drugs should not be used in children younger than 1 month.
  • Macrobid and generic Macrobid: These drugs are not used for the prevention of urinary tract infections.
Senior dosage (ages 65 years and older)

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects.

Your doctor may start you on a lowered dosage or a different treatment schedule. This can help keep levels of this drug from building up too much in your body.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always to speak with your doctor or pharmacist about dosages that are right for you.
Pharmacist's Advice
Healthline Pharmacist Editorial Team

Nitrofurantoin comes with serious risks if you don’t take it as prescribed.

If you stop taking the drug suddenly or don’t take it at all

Your urinary tract infection may not go away and may get worse. If you stop taking this drug suddenly, the bacteria that caused your urinary tract infection could become resistant to this drug. That means it won’t work for you anymore.

If you miss doses or don’t take the drug on schedule

Your medication may not work as well or may stop working completely. The bacteria that caused your urinary tract infection could become resistant to this drug. That means it won’t work for you anymore. For this drug to work well, a certain amount needs to be in your body at all times.

If you take too much

You could have dangerous levels of the drug in your body. Symptoms of an overdose of this drug can include:

  • nausea
  • vomiting

If you think you’ve taken too much of this drug, call your doctor or local poison control center. If your symptoms are severe, call 9-1-1 or go to the nearest emergency room right away.

What to do if you miss a dose

Take your dose as soon as you remember. But if you remember just a few hours before your next scheduled dose, take only one dose. Never try to catch up by taking two doses at once. This could result in dangerous side effects.

How to tell if the drug is working

The symptoms of your urinary tract infection should get better.

Nitrofurantoin is used for short-term treatment of urinary tract infections.

The brand-name drugs Furadantin and Macrodantin and their generic drugs may also be used for long-term prevention of urinary tract infections.

Take nitrofurantoin with food

This may help reduce upset stomach and allow the drug to work better.

Store this drug carefully

  • Store nitrofurantoin at a temperature between 68°F and 77°F (20°C and 25°C). Macrobid and generic Macrobid can be stored between 59°F and 86°F (15°C and 30°C).
  • Keep nitrofurantoin away from light.
  • Don’t store this medication in moist or damp areas, such as bathrooms.

A prescription for this medication may not be refillable

Let your doctor know if you still you have symptoms of a urinary tract infection after taking all of your nitrofurantoin.

Travel

When traveling with your medication:

  • Always carry your medication with you. When flying, never put it into a checked bag. Keep it in your carry-on bag.
  • Don’t worry about airport x-ray machines. They can’t hurt your medication.
  • You may need to show airport staff the pharmacy label for your medication. Always carry the original prescription-labeled box with you.
  • Don’t put this medication in your car’s glove compartment or leave it in the car. Be sure to avoid doing this when the weather is very hot or very cold.

Clinical monitoring

Your may doctor may monitor you during your treatment. If you are taking nitrofurantoin for long-term prevention of urinary tract infections, your doctor may do blood tests from time to time. These tests check your liver and kidney function.

Are there any alternatives?

There are other drugs available to treat your condition. Some may be better suited for you than others. Talk to your doctor about other drug options that may work for you.

What does the pill look like?

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How Much Does nitrofurantoin Cost?

Oral capsule

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Lowest price for nitrofurantoin

Walmart $16.88
Membership warehouse $23.55
Kroger Pharmacy $23.65
These prices represent the lowest priced national pharmacies for nitrofurantoin on GoodRx. They may be lower than your insurance.

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These prices represent the lowest priced national pharmacies for nitrofurantoin on GoodRx. They may be lower than your insurance.

Show Sources

Content developed in collaboration with University of Illinois-Chicago, Drug Information Group

Medically reviewed by Creighton University, Center for Drug Information and Evidence-Based Practice on November 25, 2016

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.
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