How Safe Is Nitrofurantoin in Pregnancy – Warnings, Dosages, FAQs

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Nitrofurantoin is a widely prescribed antibiotic that treats urinary tract infections. This medication can also prevent bacterial infections in the lower urinary tract. Nitrofurantoin is a relatively safe drug with very minimal side effects for patients, except on rare occasions. For instance, using Nitrofurantoin in pregnancy may come with certain conditions, even though the medication is generally safe with rare, severe side effects.

This article discusses using Nitrofurantoin in pregnancy, warnings, precautions, and answers to FAQs. Read this article to learn more about using Nitrofurantoin during pregnancy and breastfeeding.

What is nitofurantoin?

Nitrofurantoin is an antibiotic that treats infections caused by certain bacteria in the urinary tract, like acute cystitis and asymptomatic bacteriuria. This medication is available as a generic and brand-name version. Nitrofuratoin’s brand names are Macrobid and Macrodantin.

This drug is available in oral capsule or tablet form and is usually prescribed for UTIs because of its unique mechanism of action when used. Nitrofurantoin is rapidly filtered from the blood and passed down to the urine in the bladder.

The antibiotic properties of the medication then fight against specific bacteria causing infections by inhibiting their growth and killing them. This mechanism of action means that Nitrofurantoin will not work for other infections outside of the lower urinary tract. Nitrofurantoin is also available as an oral suspension.

Patients require a prescription to purchase Nitrofurantoin.

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How nitrofurantoin works

Nitrofurantoin is usually prescribed to treat UTIs and bacteria infections in the urinary system, including the kidneys, bladder, and gut. The FDA approved this medication for UTI treatment because it shows good action against infections caused by Enterococcus, Klebsiella, Escherichia coli, Enterobacter cystitis, and Staphylococcus aureus. This medication is highly effective against asymptomatic bacteriuria.

This medication also treats ear infections, pyelitis, strep throat, and mild lower UTIs. It is also used as prophylaxis for UTIs, especially after surgical treatments.

Even though this drug is effective against bacterial infections, it will not work for flu, colds, or other infections caused by viruses.

The drug produces bactericidal qualities when the hydantoin ring with a nitro-substituted furanyl side chain is metabolized in the bacteria to create reactive compounds. This antibiotic action of the drug occurs by changing the bacteria’s DNA and other vital genetic structures.

Nitrofurantoin is effective against gram-positive bacteria (staphylococci and streptococci) and gram-negative bacteria (E. coli, Klebsiella spp., and Citrobacter spp.).

Urinary Tract Infections in pregnancy

A urinary tract infection is in the body’s urinary system, including ureters, kidneys, bladder, and urethra. Bacteria cause Most urinary tract infections and can be treated with an entire course of antibiotics prescribed by a doctor.

Anyone can get a UTI, but they’re most common in women. Urinary tract infections can be extra concerning for pregnant women and can result in unwanted complications, including congenital disabilities in newborn babies.

If you’re pregnant and you suspect you have a UTI, you should inform your doctor so they can carry out the required tests and prescribe treatment. With the appropriate care, you and your baby should be okay. UTIs in pregnant women may cause preterm labor and low birth weight.

Read also: Can Metronidazole Treat Chlamydia?

Nitrofurantoin in pregnancy

Nitrofurantoin is a potent antibiotic and is usually prescribed to treat UTIs. The medication is safe for use during pregnancy. However, your healthcare expert will advise you to avoid the medication in the third trimester of pregnancy.

Nitrofurantoin may cause unwanted complications with the unborn baby’s red blood cells. This adverse effect is not common, but healthcare experts usually recommend different antibiotics for pregnant people in their third trimester.

In addition, Nitrofurantoin is safe for most breastfeeding mothers, following recommendations from their healthcare experts.

If your doctor declares your baby healthy, you can safely use Nitrofurantoin while breastfeeding. This is because the medication passes into breast milk in minute quantities and is unlikely to trigger any side effects in your infant.

Despite this, it is best to use Nitrofurantoin briefly during breastfeeding. If you must take it for a more extended period, you should inform your healthcare provider.

Your primary care expert will advise you to avoid Nitrofurantoin while breastfeeding for the following reasons.

Suppose your baby has glucose-6-phosphate dehydrogenase (G6PD) deficiency. This is an uncommon condition affecting the red blood cells.

If your baby has jaundice, you should not use Nitrofurantoin while breastfeeding. Symptoms of jaundice include dark urine, pale poo, and yellowing of the white of the eyes and skin.

Avoid Nitrofurantoin if your baby has a gastrointestinal upset or is not feeding well.

In addition, you should avoid this medication if your newborn has oral thrush- a fungal infection in the mouth.

Nitrofurantoin in pregnancy- safe use

Suppose you’re pregnant and you have a UTI; you must inform your healthcare expert and get treated immediately to avoid any unwanted complications. Untreated UTIs during pregnancy can lead to preterm labor or low birth weight, among other complications.

Medication use during pregnancy must be done with utmost care and consideration with the recommendation of a qualified healthcare professional.

Most drugs used in pregnancy will cross the placenta and reach the fetus. In some cases, this may have beneficial effects on the baby. However, some medications can inhibit a baby’s development, causing unwanted birth complications.

How a medication affects fetuses mostly depends on the stage of the pregnancy when the medicine is used.

When using a medication in pregnancy, it is crucial to consider the potential effect of the drug on the unborn baby’s health against the benefits of the drug.

Because every pregnancy is unique, the decision to start, change, continue, or stop a prescription medication must be made in consultation with a qualified healthcare professional. This is to avoid possible complications like hemolytic anemia or congenital disabilities for the unborn child.

Dosage recommendations for Nitrofurantoin

Following your doctor’s instructions when using Nitrofurantoin during pregnancy is vital. For pregnant women who have recurrent episodes of acute cystitis, asymptomatic bacteriuria, or symptomatic urinary tract infections, daily antibiotic prophylaxis for the rest of the pregnancy may be a suitable treatment.

A dose of 100mg of Nitrofurantoin every night prevents recurrent UTIs in pregnant women.

In addition, pregnant women with pyelonephritis may also be required to use 100 mg every night. Make sure that you’re getting your prescription from a qualified medical professional.

For UTI treatment in pregnant women, your doctor may prescribe 100 mg of nitrofurantoin monohydrate to be used orally twice daily for 5-7 days.

The dosages for other antibiotic alternatives to Nitrofurantoin during pregnancy include:

  • Cephalexin- 250 mg twice or four times daily
  • Sulfisoxazole- 1 g four times daily
  • Amoxicillin-clavulanic acid – 250 mg four times daily
  • Erythromycin- 250-500 mg four times daily
  • Trimethoprim-sulfamethoxazole – 160/180 mg twice daily

Side effects of Nitrofurantoin

Side effects of Nitrofurantoin

Nitrofurantoin is a potent antibiotic with mostly tolerable side effects. Like other antibiotics, this medication can cause some side effects to occur. Although very rare, Nitrofurantoin can cause severe side effects that can be harmful to a patient.

Some of the common side effects include;

  • Loss of appetite
  • Diarrhea
  • Numbness
  • Drowsiness
  • Nausea and vomiting
  • Weakness
  • Fatigue
  • Hand and foot pain

Usually, these side effects will dissipate after a couple of days. However, you must contact your healthcare provider if they persist longer.

Some of the severe side effects include;

Inflammation of the liver

  • Symptoms include nausea, vomiting, yellowing of the skin, loss of appetite, dark urine, itching

Inflammation of the lungs

  • Symptoms include shortness of breath, chills, cough, chest pain, tiredness

Inflammation of the liver

  • Symptoms include nausea, vomiting, yellowing skin, loss of appetite, dark urine, and itching.

Red blood damage (hemolysis)

  • Symptoms include weakness, fatigue, pale skin

Nerve damage

  • Symptoms include weakened muscles, tingling, or numbness in your hands and feet.


  • Symptoms include stomach upset, bloody stools, loose or watery stools

When to see a doctor

You must use Nitrofurantoin as recommended by a qualified medical professional. You can only purchase this medication over the counter with a prescription.

You must use Nitrofurantoin as advised by your doctor to avoid unwanted complications to your well-being and your unborn baby’s health.

If you fail to complete the course as prescribed, the drug may stop working for you because your body will become resistant to it. This means that Nitrofurantoin will not be effective for you anymore.

You must inform your doctor if you notice any unusual feelings or sensations while using Nitrofurantoin in pregnancy. Your doctor will examine you and decide whether to change or stop your antibiotic course for you and your baby’s safety.

Read also: Is Metronidazole Safe in Pregnancy and Breastfeeding?

Frequently Asked Questions

Nitrofurantoin is safe during pregnancy, but a qualified medical expert must prescribe it. Your doctor will advise you to avoid Nitrofurantoin in the third trimester if you’re pregnant. This is because there’s a slight chance of the medication interacting negatively with your baby’s red blood cells.

Nitrofurantoin is a relatively safe antibiotic during pregnancy. However, there’s a risk of complications if used in the third trimester of pregnancy. Alternatively, amoxicillin and cephalexin are the first-choice antibiotics for UTIs during pregnancy.

Nitrofurantoin has been associated with a risk of cardiac congenital disabilities when taken during early pregnancy in the first trimester of pregnancy. Due to this, the medication is best used in the second trimester to avoid adverse reactions.

Extended Nitrofurantoin use may also cause unwanted reactions, so it’s best to follow your doctor’s recommendations on dosage durations. The required dosage is usually for 5-7 days of antibiotic therapy.

Using Nitrofurantoin for UTIs may require 3-7 days of antibiotic therapy to eliminate the infection.

You may be required to take the medication for several months to stop recurrent infections.

The content on Doctor Alexa’s blog is reviewed by Advanced practice registered nurses or pharmacist and is intended for educational purposes only. This information should not be relied upon as professional medical counsel. Be sure to always consult with your physician about the dangers and benefits of any medication, treatment or procedure.

You shouldn’t wait to see the doctor for simple health needs.