Adult dosage (ages 18–64 years)
Nitrofurantoin
Medically reviewed by Sanjai Sinha, MD. Last updated on Mar 22, 2022.
What is nitrofurantoin?
Nitrofurantoin is an antibiotic that fights bacteria in the body.
Nitrofurantoin is used to treat urinary tract infections.
Nitrofurantoin may also be used for purposes not listed in this medication guide.
Warnings
You should not take nitrofurantoin if you have severe kidney disease, urination problems, or a history of jaundice or liver problems caused by nitrofurantoin.
Do not take this medicine if you are in the last 2 to 4 weeks of pregnancy.
Before taking this medicine
You should not take nitrofurantoin if you are allergic to it, or if you have:
- severe kidney disease;
- a history of jaundice or liver problems caused by taking nitrofurantoin;
- if you are urinating less than usual or not at all; or
- if you are in the last 2 to 4 weeks of pregnancy.
Do not take nitrofurantoin if you are in the last 2 to 4 weeks of pregnancy.
To make sure nitrofurantoin is safe for you, tell your doctor if you have:
- kidney disease;
- anemia;
- diabetes;
- an electrolyte imbalance or vitamin B deficiency;
- glucose-6-phosphate dehydrogenase (G6PD) deficiency; or
- any type of debilitating disease.
FDA pregnancy category B. This medicine is not expected to be harmful to an unborn baby during early pregnancy. Tell your doctor if you are pregnant or plan to become pregnant during treatment.
Nitrofurantoin can pass into breast milk and may harm a nursing baby. You should not breast-feed while you are taking this medicine.
Nitrofurantoin should not be given to a child younger than 1 month old.
Related/similar drugs
How should I take nitrofurantoin?
Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.
Take nitrofurantoin with food.
Shake the oral suspension (liquid) well just before you measure a dose. Measure liquid medicine with the dosing syringe provided, or with a special dose-measuring spoon or medicine cup. If you do not have a dose-measuring device, ask your pharmacist for one.
You may mix your liquid dose with water, milk, or fruit juice to make it easier to swallow. Drink the entire mixture right away.
Use this medicine for the full prescribed length of time. Your symptoms may improve before the infection is completely cleared. Skipping doses may also increase your risk of further infection that is resistant to antibiotics. Nitrofurantoin will not treat a viral infection such as the common cold or flu.
Nitrofurantoin is usually given for up to 3 to 7 days.
If you use this medicine long-term, you may need frequent medical tests at your doctor’s office.
Nitrofurantoin can cause unusual results with certain lab tests for glucose (sugar) in the urine. Tell any doctor who treats you that you are using nitrofurantoin.
Store at room temperature away from moisture, heat, and light.
What happens if I miss a dose?
Take the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not take extra medicine to make up the missed dose.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
What to avoid
Antibiotic medicines can cause diarrhea, which may be a sign of a new infection. If you have diarrhea that is watery or has blood in it, call your doctor. Do not use any medicine to stop the diarrhea unless your doctor has told you to.
Avoid using antacids without your doctor’s advice. Use only the type of antacid your doctor recommends. Some antacids can make it harder for your body to absorb nitrofurantoin.
Nitrofurantoin side effects
Get emergency medical help if you have any of these signs of an allergic reaction to nitrofurantoin: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have:
- diarrhea that is watery or bloody;
- sudden chest pain or discomfort, wheezing, dry cough or hack;
- new or worsening cough, trouble breathing;
- fever, chills, body aches, tiredness, unexplained weight loss;
- numbness, tingling, or pain in your hands or feet;
- liver problems–nausea, upper stomach pain, itching, tired feeling, loss of appetite, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes); or
- lupus-like syndrome–joint pain or swelling with fever, swollen glands, muscle aches, chest pain, vomiting, unusual thoughts or behavior, and patchy skin color.
Serious side effects may be more likely in older adults and those who are ill or debilitated.
Common nitrofurantoin side effects may include:
- headache, dizziness;
- gas, upset stomach;
- mild diarrhea; or
- vaginal itching or discharge.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
Dosing information
Usual Adult Dose for Cystitis:
Regular release: 50 to 100 mg orally 4 times a day for 1 week or for at least 3 days after urine sterility is obtained
Dual release: 100 mg orally twice a day for 7 days
Usual Adult Dose for Cystitis Prophylaxis:
Regular release: 50 to 100 mg orally once a day at bedtime
Usual Pediatric Dose for Cystitis:
Regular release:
1 month or older: 5 to 7 mg/kg/day (up to 400 mg/day) orally in 4 divided doses
Dual release:
Greater than 12 years: 100 mg orally twice a day for 7 days
Usual Pediatric Dose for Cystitis Prophylaxis:
Regular release:
1 month or older: 1 to 2 mg/kg/day (up to 100 mg/day) orally in 1 to 2 divided doses
What other drugs will affect nitrofurantoin?
Other drugs may interact with nitrofurantoin, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.
Where can I get more information?
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use nitrofurantoin only for the indication prescribed.
Frequently asked questions
- What antibiotics are used to treat UTI?
- What is “dual release” nitrofurantoin?
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- Urinary Tract Infection
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Nitrofurantoin, oral capsule
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
- itching
- yellowing of your skin or the whites of your eyes
- nausea or vomiting
- dark urine
- loss of appetite
- numbness or tingling in your hands and feet
- muscle weakness
- tiredness
- weakness
- pale skin
- 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:
- Research in animals has not shown a risk to the fetus when the mother takes the drug.
- 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
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:
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.
Last medically reviewed on August 12, 2021
- Urinary Tract Infection
- Infectious Diseases / Bacteria / Viruses
- Urology / Nephrology
- Drugs
How we reviewed this article:
Medical News Today has strict sourcing guidelines and draws only from peer-reviewed studies, academic research institutions, and medical journals and associations. We avoid using tertiary references. We link primary sources — including studies, scientific references, and statistics — within each article and also list them in the resources section at the bottom of our articles. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.
- Furadantin — nitrofurantoin suspension. (2021).
https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=00af0dea-ac7b-43f2-9f51-2a9f9e7f7d21&type=display - Macrobid — nitrofurantoin monohydrate/macrocrystalline capsule. (2019).
http://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=8f270a9f-12a1-44d4-bc7e-873613555801 - Macrodantin — nitrofurantoin macrocrystals capsule. (2017).
http://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=89d8696b-f9ce-9691-6222-8416ca143bba
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