At a glance

  • Available strengths: 50 mg, 100 mg
  • Active ingredient: Nitrofurantoin
  • Drug class: Urinary antibacterial (antibiotic)
  • Common brands in the USA: Macrobid (nitrofurantoin monohydrate/macrocrystals), Macrodantin (nitrofurantoin macrocrystals)
  • Primary use: Treatment and prevention of uncomplicated urinary tract infections caused by susceptible bacteria

Looking for something specific? Jump to alternatives, prices, or USA legal notes.

What nitrofurantoin treats

Nitrofurantoin is an antibiotic that concentrates in the urine and targets susceptible bacteria in the lower urinary tract. It is commonly prescribed for acute uncomplicated cystitis and, in selected cases, for prevention of recurrent urinary tract infections.

It does not treat viral infections and is not appropriate for suspected kidney infection or prostatitis.

How to take it

Always use nitrofurantoin exactly as your prescriber directs. General guidance:

  • Take with food to improve absorption and reduce stomach upset.
  • Drink adequate fluids unless your clinician advises otherwise.
  • Avoid antacids containing magnesium trisilicate while on nitrofurantoin.
  • Complete the full course even if you feel better early.

Common adult regimens (may vary by prescriber):

  • Macrobid 100 mg: one capsule twice daily for 5 days for uncomplicated UTI.
  • Macrodantin 50–100 mg: four times daily for 5–7 days for uncomplicated UTI.
  • Prophylaxis of recurrent UTI (select patients): 50–100 mg once daily at bedtime. Duration and need should be periodically reassessed.

Missed dose: If you forget a dose, take it when you remember. If it is nearly time for your next dose, skip the missed dose. Do not double up.

Questions about use? See safety or speak with your health care provider.

Storage

  • Keep at 59 to 86 F (15 to 30 C), away from heat, moisture, and direct light.
  • Do not store in the bathroom.
  • Keep out of reach of children and pets.

Safety and warnings

Do not use nitrofurantoin if

  • You have decreased kidney function, markedly reduced urination, or cannot urinate.
  • You are allergic to nitrofurantoin or any component of the product.
  • You are at term pregnancy (38 to 42 weeks), are about to go into labor, or are in labor.
  • You have a history of liver injury or jaundice related to nitrofurantoin.
  • The intended patient is younger than 1 month old.

If any of the above apply, contact your clinician immediately.

Tell your clinician before use if you have

  • G6PD deficiency, anemia, vitamin B deficiency, or electrolyte problems.
  • Kidney disease, liver disease, or nerve disorders such as peripheral neuropathy.
  • Diabetes.
  • Past lung issues including interstitial pneumonitis or pulmonary fibrosis.
  • Very poor overall health status.
  • Any drug, food, or other allergies.
  • Pregnancy, plans to become pregnant, or are breast-feeding.
  • Use of prescription or nonprescription drugs, herbal products, or supplements.

Drug and product interactions

  • Probenecid or sulfinpyrazone can raise nitrofurantoin levels and side effect risk or reduce urinary concentrations, lowering effectiveness.
  • Antacids with magnesium trisilicate may reduce absorption and effectiveness.

Not all interactions are listed. Review all medications with your pharmacist or prescriber before starting, stopping, or changing any dose.

Important safety points

  • Nitrofurantoin may cause dizziness or drowsiness. Until you know how you respond, avoid driving or using machinery. Alcohol can worsen these effects.
  • Rare but serious lung reactions can occur, especially with long-term use. Seek care urgently for fever, chills, chest pain, trouble breathing, or a persistent cough.
  • Rare but serious liver problems can occur. Contact a clinician for yellowing of skin or eyes, pale stools, severe nausea, loss of appetite, or stomach pain.
  • Peripheral neuropathy has occurred, with higher risk in patients with kidney disease, diabetes, anemia, or low vitamin B. Report numbness, tingling, or burning in hands or feet.
  • Antibiotic-associated diarrhea, including C. difficile, may occur during or after therapy. For severe diarrhea, bloody stools, or cramping, seek medical help; do not self-treat.
  • Long or repeated use can lead to secondary infections; inform your prescriber if new symptoms appear.
  • Urine may become dark yellow or brown; this is usually harmless.
  • For some diabetes urine glucose tests, results may be inaccurate while on nitrofurantoin.
  • Older adults may be more susceptible to lung or liver side effects.
  • Breast-feeding: avoid in infants under 1 month; for older infants, discuss risks and benefits with a clinician.

Routine monitoring (kidney, liver, and sometimes lung function) may be recommended during longer courses. Keep all scheduled appointments.

Possible side effects

Many people have no or only mild effects.

Common, usually mild

  • Nausea or decreased appetite
  • Gas
  • Headache
  • Mild diarrhea

Seek medical attention immediately for

  • Severe allergic reactions: rash, hives, itching, hoarseness, swelling of face, lips, tongue, or throat, trouble breathing, chest tightness.
  • Severe or persistent diarrhea; bloody or watery stools; intense stomach pain or cramps.
  • Shortness of breath, fever, chills, chest pain, or a persistent or unusual cough.
  • Yellowing of the skin or eyes, pale stools, severe nausea or loss of appetite.
  • Blurred vision or vision changes; butterfly-shaped rash on cheeks and nose.
  • Mood or mental changes; confusion; persistent headache; unusual tiredness or weakness.
  • Bluish skin or nails; unusual bruising or bleeding.
  • Tingling, numbness, or burning in hands or feet; joint or muscle pain; red, swollen, blistered, or peeling skin.

This is not a complete list. If you notice anything concerning, contact your clinician or pharmacist.

Alternatives and similar medicines

Nitrofurantoin is a first-line option for uncomplicated UTIs in many adults. Depending on your health history, local resistance patterns, kidney function, and allergy profile, clinicians may consider these alternatives:

  • Trimethoprim-sulfamethoxazole (TMP-SMX) 160/800 mg twice daily for 3 days if local E. coli resistance is low and no sulfa allergy. Often inexpensive; not ideal if taken in the prior 3 months or resistance is high.
  • Fosfomycin tromethamine 3 g single oral dose for uncomplicated cystitis. Useful for certain resistant organisms; may cost more but is convenient as one dose.
  • Pivmecillinam FDA-approved in 2024 for uncomplicated UTI in adult women. A beta-lactam option with activity against common uropathogens.
  • Beta-lactams such as amoxicillin-clavulanate or cephalexin for 5–7 days when other first-line options are not suitable.
  • Fluoroquinolones (for example, ciprofloxacin) are generally reserved due to safety concerns and resistance; typically used when alternatives are not appropriate.
  • Methenamine hippurate a non-antibiotic urinary antiseptic used for prevention of recurrent UTIs in select patients.

Choice of therapy should be individualized by a licensed clinician. For prices, see Typical USA prices.

Typical USA prices (cash, without insurance)

Prices vary by pharmacy, location, and available discounts or coupons. The ranges below are approximate for common quantities:

  • Nitrofurantoin 100 mg (generic Macrobid), 10–14 capsules: about $10–$35 USD
  • Macrobid 100 mg (brand), 10–14 capsules: about $90–$220 USD
  • Nitrofurantoin 50 mg (generic Macrodantin), 28–40 capsules: about $12–$45 USD
  • Prophylaxis cost (generic nitrofurantoin 30 tablets/capsules): roughly $8–$30 USD per month
  • TMP-SMX 160/800 mg, 6 tablets (3-day course): about $4–$20 USD
  • Fosfomycin 3 g single dose: about $80–$140 USD
  • Amoxicillin-clavulanate 875/125 mg, 10 tablets: about $10–$40 USD
  • Cephalexin 500 mg, 28 capsules: about $8–$25 USD
  • Ciprofloxacin 250–500 mg, 6–10 tablets: about $6–$25 USD

Using discount programs, coupons, or employer/insurance plans may significantly reduce out-of-pocket costs.