1. Nitrofurantoin oral capsule is available as both generic and brand-name drugs. Brand names: Macrobid and Macrodantin.
  2. Nitrofurantoin is also available in an oral suspension.
  3. Nitrofurantoin oral capsule is used to prevent and treat urinary tract infections that are caused by certain bacteria.
  • Lung inflammation warning: 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 warning: 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 warning: This drug may cause nerve damage. This damage can cause numbness and pain, especially in your hands and feet.
  • Red blood cell damage warning: 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 warning: 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. Check with your doctor before treating diarrhea.

Nitrofurantoin is a prescription drug that comes as an oral capsule and an oral suspension.

Nitrofurantoin oral capsule is available as the brand-name drugs Macrobid and Macrodantin. It’s also available as a generic drug. Generic drugs usually cost less than the brand-name version. In some cases, they may not be available in all strengths or forms as the brand-name drug.

Why it’s used

Nitrofurantoin oral capsule 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. 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.

Nitrofurantoin oral capsule may cause drowsiness. It may also cause other side effects.

More common side effects

The more common side effects of nitrofurantoin can include:

  • nausea
  • vomiting
  • loss of appetite
  • stomach pain
  • diarrhea
  • numbness 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 with your doctor or pharmacist.

Serious side effects

Call your doctor right away if you have serious side effects. 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 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
  • Diarrhea. Symptoms can include:
    • very loose or watery stools
    • bloody stools
    • stomach pain

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 professional who knows your medical history.

Nitrofurantoin oral capsule 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 with your doctor or pharmacist.

Examples of drugs that can cause interactions with nitrofurantoin are listed below.

Drugs you should not use with nitrofurantoin

Do not take these drugs with nitrofurantoin. 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, while reduced levels in your urine can make 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 professional about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.

Nitrofurantoin oral capsule comes with several warnings.

Allergy warning

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 911 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).

Warnings for people with certain health conditions

For 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.

For people with liver disease: You should not use nitrofurantoin. It can make your liver damage worse.

Warnings for other groups

For 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 with 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

Call your doctor if you become pregnant while taking this drug.

For women who are breastfeeding: Nitrofurantoin may pass into breast milk and cause side effects in a child who is breastfed. Talk with your doctor about breastfeeding your child. You may need to decide whether to stop breastfeeding or stop taking this medication.

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.

For children: Do not use any form of nitrofurantoin in infants younger than 1 month. Macrodantin and its generic form 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.

This dosage information is for nitrofurantoin 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

Forms and strengths

Generic: Nitrofurantoin

  • Form: oral capsule (generic for Macrobid)
  • Strength: 100 mg (75 mg nitrofurantoin monohydrate and 25 mg nitrofurantoin macrocrystals)
  • Form: oral capsule (generic for Macrodantin)
  • Strengths: 25 mg, 50 mg, 100 mg

Brand: Macrobid

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

Brand: Macrodantin

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

Dosage for treatment of urinary tract infections

Adult dosage (ages 18–64 years)

  • Macrodantin and its generic form: 50–100 mg four times per day. Length of treatment varies.
  • Macrobid and its generic forms: 100 mg every 12 hours for 7 days.

Child dosage (ages 12–17 years)

  • Macrodantin and its generic form: 5–7 mg/kg of body weight per day in four divided doses. Length of treatment may vary.
  • Macrobid and its generic form: 100 mg every 12 hours for 7 days.

Child dosage (ages 1 month–11 years)

  • Macrodantin and its generic form: 5–7 mg/kg of body weight per day in four divided doses. Length of treatment may vary.
  • Macrobid and its generic form: 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)

  • Macrodantin and its generic form: These drugs should not be used in children younger than 1 month.
  • Macrobid and its generic form: 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.

Dosage for prevention of urinary tract infections

Adult dosage (ages 18–64 years)

  • Macrodantin and its generic form: 50–100 mg at bedtime.
  • Macrobid and its generic form: These drugs are not used for the prevention of urinary tract infections.

Child dosage (ages 1 month–17 years)

  • Macrodantin and its generic form: 1 mg/kg of body weight once per day or divided into two doses per day.
  • Macrobid and its generic form: These drugs are not used for the prevention of urinary tract infection.

Child dosage (ages 0–1 month)

  • Macrodantin and its generic form: These drugs should not be used in children younger than 1 month.
  • Macrobid and its generic form: 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 speak with your doctor or pharmacist about dosages that are right for you.

Nitrofurantoin oral capsule is used for short-term treatment of urinary tract infections. The brand-name drug Macrodantin and its generic form may also be used for long-term prevention of urinary tract infections.

This drug 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 seek guidance from the American Association of Poison Control Centers at 800-222-1222 or through their online tool. But if your symptoms are severe, call 911 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.

Keep these considerations in mind if your doctor prescribes nitrofurantoin oral capsule for you.

General

Take nitrofurantoin with food. This may help reduce upset stomach symptoms and allow the drug to work better.

Storage

  • 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.

Refills

A prescription for this medication is refillable. You should not need a new prescription for this medication to be refilled. Your doctor will write the number of refills authorized on your prescription.

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 container 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 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.

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

Disclaimer: Medical News Today 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 another 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.