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Macrobid

Generic name: nitrofurantoin

Last updated August 26, 2026 0 views Reviewed by Philip Thornton, DipPharm
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What is Macrobid?

Macrobid is an antibiotic that fights bacteria in the body.

Macrobid is used to treat urinary tract infections.

Macrobid may also be used for purposes not listed in this medication guide.

How should I take Macrobid?

Take Macrobid exactly as prescribed by your doctor. Follow all directions on your prescription label. Do not take this medicine in larger or smaller amounts or for longer than recommended.

Take Macrobid 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. Macrobid will not treat a viral infection such as the common cold or flu.

Macrobid is usually given for 5 days in females and 7 days in males for uncomplicated UTI.

If you use this medicine long-term, for prevention of UTI, you may need frequent medical tests at your doctor's office.

Macrobid can cause unusual results with certain lab tests for glucose (sugar) in the urine. Tell any doctor who treats you that you are using Macrobid.

Store at room temperature away from moisture, heat, and light.

Warnings

You should not take Macrobid if you have severe kidney disease, complicated urinary tract infection, or a history of jaundice or liver problems caused by nitrofurantoin.

Do not take Macrobid if you are in the last 2 to 4 weeks of pregnancy.

Before taking this medicine

You should not take Macrobid if you are allergic to nitrofurantoin, 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 Macrobid if you are in the last 2 to 4 weeks of pregnancy.

To make sure Macrobid 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.

Macrobid is not expected to be harmful to an unborn baby during early pregnancy, but should not be taken if you are in the last 2 to 4 weeks of pregnancy. Tell your doctor if you are pregnant or plan to become pregnant during treatment before taking Macrobid.

Nitrofurantoin can pass into breast milk and may harm a nursing baby. Tell your doctor if you are breast-feeding; you may need to decide whether to stop nursing or stop taking this medicine.

Macrobid should not be given to a child younger than 1 month old.

Macrobid side effects

Get emergency medical help if you have any of these signs of an allergic reaction to Macrobid: hives; difficulty 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 Macrobid 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 obtainedDual 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 dosesDual 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 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.

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.

What other drugs will affect Macrobid?

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.

Tell your doctor if you are taking probenecid or sulfinpyrazone. These medicines can increase the levels of nitrofurantoin in your blood, which may increase the risk of side effects and make the medicine less effective in treating your urinary tract infection.

Common questions about Macrobid

What is "dual release" nitrofurantoin?
Nitrofurantoin is an antibiotic used to treat and prevent urinary tract infections (UTIs). It is available in two main capsule formulations: Macrodantin (macrocrystalline nitrofurantoin) – often called regular-release. Macrobid (nitrofurantoin monohydrate/macrocrystals) – often called dual-release Continue reading
How long does nitrofurantoin take to work for a UTI?
Nitrofurantoin usually starts working in the bladder within hours, but most people notice symptom improvement within 24–48 hours. Full relief typically occurs over 3–5 days when the drug is taken as prescribed for an uncomplicated urinary tract infection (UTI). Continue reading
Can you drink alcohol while taking nitrofurantoin?
Most evidence suggests there is no direct, proven chemical interaction between nitrofurantoin and alcohol, meaning an occasional drink is unlikely to inactivate the antibiotic or cause a specific “reaction” in most healthy adults. However, alcohol can worsen side effects, stress the liver, and impair recovery from a urinary tract infection (UTI). Continue reading

Related medicines

Before you take this medicine: the information on this page is general and may not cover your personal circumstances. Read the label supplied with your medicine and ask a pharmacist or doctor if you are unsure, especially if you are pregnant, breastfeeding, taking other medicines or managing a long-term condition.
General medicine information Consumer-friendly language Source: Drugs.com

Content is provided for education and is not medical advice. See our medical disclaimer. Source page medically reviewed by Philip Thornton, DipPharm on August 26, 2026.