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Overview: Nitrofurantoin is an antibiotic used to treat bladder infections. It works by blocking certain types of bacteria from growing. Common side effects include nausea and vomiting, loss of appetite, uncontrollable eye movements, feeling off-balance, and headache. Contact your health care provider or seek care right away if you have breathing problems or wheezing, fever and chills with cough or chest pain, your skin or the whites of your eyes turning yellowish, numbness or weakness in your arms or legs, or watery diarrhea that does not go away. Nitrofurantoin comes as a capsule or liquid that is swallowed.

Uses

What is nitrofurantoin used for?

Nitrofurantoin is commonly used to treat bladder infections. 

Nitrofurantoin may not be the right medicine for all bladder infections, depending on which germs are causing the infection. Bacteria in some locations may have become resistant to nitrofurantoin, which will make it not work as well.

Nitrofurantoin may also be used for other conditions as determined by your health care provider.

How does nitrofurantoin work (mechanism of action)?

Nitrofurantoin kills certain types of bacteria by blocking their ability to create proteins and other substances that they need to grow and reproduce.

How is nitrofurantoin supplied (dosage forms)?

Brands and other names

  • Furadantin
  • Macrobid
  • Macrodantin

Dosage forms and strengths

  • 25 mg, 50 mg, 100 mg oral capsules
  • 25 mg/5 mL oral suspension
  • 50 mg/mL oral suspension

How should I store nitrofurantoin?

Nitrofurantoin should be stored at room temperature, between 68 F and 77 F (20 C and 25 C). It can be exposed to temperatures between 59 F and 86 F (15 C and 30 C) for shorter periods of time, such as when transporting it. Store in a cool, dry place. Protect from light.

Side Effects

What are the most common side effects of nitrofurantoin?

The most common side effects of nitrofurantoin are listed below. Tell your health care provider if you have any of these side effects that bother you.

  • Nausea and vomiting
  • Loss of appetite
  • Uncontrollable eye movements
  • Feeling off-balance 
  • Headache
  • Severe allergic reactions (see below)
  • Lung problems (see below)
  • Liver damage (see below)
  • Nerve problems (see below)
  • Anemia 

There may be other side effects of nitrofurantoin that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of nitrofurantoin?

While less common, the most serious side effects of nitrofurantoin are described below, along with what to do if they happen.

Severe Allergic Reactions. Nitrofurantoin may cause allergic reactions, which can be serious. Stop using nitrofurantoin and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching or skin rash
  • Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Lung Problems. Nitrofurantoin may cause problems with your lungs. Stop taking nitrofurantoin and call your health care provider right away if you have any of the following symptoms of a lung problem.

  • Fever and chills
  • Cough
  • Chest pain
  • Shortness of breath
  • Feeling unwell

Liver Damage. Liver damage, also called hepatotoxicity, can happen when taking nitrofurantoin. Call your health care provider right away if you have any of the following symptoms of liver damage.

  • Nausea or vomiting
  • Stomach or belly pain
  • Fever
  • Weakness or unusual tiredness
  • Itching
  • Loss of appetite
  • Light-colored poop
  • Dark-colored urine
  • Your skin or the whites of your eyes turning yellowish in color (also called jaundice)

Nerve Problems. Nerves are the fibers that carry sensations from your body to the brain. Damage to these nerves, called peripheral neuropathy, can happen in people who are taking nitrofurantoin. Stop taking nitrofurantoin and call your health care provider if you have pain, burning, tingling, numbness, or weakness in your arms, hands, legs, or feet.

Antibiotic-Associated Diarrhea. An overgrowth of germs called Clostridioides difficile, or “C. diff,” can happen in your gut with many types of antibiotics, including nitrofurantoin. This can cause a condition known as antibiotic-associated diarrhea and can happen even up to 2 months after stopping the antibiotic. Call your health care provider right away if you have any of the following symptoms of this condition.

  • Watery diarrhea
  • Diarrhea that does not go away
  • Blood in your stool (poop)
  • Severe stomach cramps
  • Fever that starts after you start or finish the medicine

Warnings & Precautions

Who should not use nitrofurantoin?

Allergies to Ingredients. People who are allergic to any of the following should not take nitrofurantoin.

  • Nitrofurantoin
  • Furadantin
  • Macrobid
  • Macrodantin
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific nitrofurantoin products they stock.

Liver Problems with Previous Nitrofurantoin Use. Nitrofurantoin should not be used if your liver was not working as well as it should have been while previously taking it. Tell your health care provider if you have previously had liver problems while taking nitrofurantoin.

Kidney Problems. Nitrofurantoin should not be used if your kidneys are not working as well as they should be. If there is a concern about the health of your kidneys, your health care provider may do tests to know if they are working well enough to take this medicine.

Pregnancy. Do not take nitrofurantoin if you are 38 weeks or more into your pregnancy, in labor, or soon to be in labor. See the Pregnancy section for more details.

Newborn. Nitrofurantoin should not be used in babies under 1 month of age. Contact your health care provider before giving this medicine to a baby less than 1 month of age. 

What should I know about nitrofurantoin before using it?

Do not take nitrofurantoin unless it has been prescribed to you by a health care provider. Take it as prescribed. Taking nitrofurantoin in a way other than it was prescribed may increase the chance that the bacteria will become resistant to nitrofurantoin. This may cause nitrofurantoin to not work as well in the future. Only take nitrofurantoin for an infection if your health care provider has prescribed it for this reason. If symptoms of a bladder infection return after taking nitrofurantoin, contact your health care provider.

Do not share nitrofurantoin with other people, even if they have the same condition as you. It may harm them.

Keep nitrofurantoin out of the reach of children.

Your pee may appear brown because of the medicine. 

Nitrofurantoin can affect your alertness or coordination. Do not drive or do other activities that require alertness or coordination until you know how nitrofurantoin affects you.

Take nitrofurantoin with food to help the medicine get absorbed into your body.

Macrodantin capsules can be opened and mixed with food or water.

Macrobid capsules should not be opened as this may interfere with the way the medicine is released into the body.

For nitrofurantoin oral liquid, shake the bottle well before each use and use an accurate measuring device to measure your dose. A household spoon is not an accurate measuring device and may cause you to take the wrong dose. Ask your pharmacist what measuring device to use.

People who are 65 and older can be at greater risk for some side effects from nitrofurantoin. Talk to your health care provider about your risks if you are in this age group.

What should I tell my health care provider before using nitrofurantoin?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if nitrofurantoin is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

Other Medicines and Supplements. Nitrofurantoin may interact with other medicines and supplements. Before taking nitrofurantoin, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Pregnancy. Do not take nitrofurantoin at 38 weeks or later in pregnancy. Taking nitrofurantoin during this time may be harmful. Tell your health care provider if you are or plan to become pregnant. Your health care provider will let you know if you should take nitrofurantoin while you are pregnant or trying to get pregnant.

Breastfeeding. Do not take nitrofurantoin while breastfeeding a baby that is less than 1 month old or who has glucose-6-phosphate dehydrogenase (G6PD) deficiency without talking to your health care provider. Taking nitrofurantoin and breastfeeding may cause harm to the baby. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should take nitrofurantoin while breastfeeding.

Interactions

Does nitrofurantoin interact with foods or drinks?

There are no known interactions between nitrofurantoin and foods or drinks.

There are no known interactions between nitrofurantoin and alcohol.

Does nitrofurantoin interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before taking nitrofurantoin.

  • Antacids which contain magnesium trisilicate, including Gaviscon
  • Probenecid, which is a medicine commonly used for gout

This may not be a complete list of medicines that can interact with nitrofurantoin. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much nitrofurantoin?

If you or someone else has used too much nitrofurantoin, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of nitrofurantoin?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.

It is important to complete your prescribed course of nitrofurantoin, even if your symptoms get better or go away. This will reduce the risk that future infections are resistant to nitrofurantoin or other similar medicines.