Nitrofurantoin
Pronunciation: nye-troe-fyoor-AN-toyn.
- Generic name
- Nitrofurantoin
- Brand names
- Macrodantin, Macrobid, Nifuran, Nitrofur SR, Urofurantoin, Teva-Nitrofurantoin
- Drug class
- Antibiotic (Nitrofuran derivative)
Availability and supply rules vary by country
Trade names by country: United States · Canada
Australia: · Full directory
What Nitrofurantoin is and how it works
Uses, formulations, monitoring, and supply rules can differ by patient, product, and country. Follow the exact local product information and professional advice.
Mechanism of action: how Nitrofurantoin works
Nitrofurantoin is reduced by bacterial flavoproteins to reactive intermediates that inactivate or alter bacterial ribosomal proteins and other macromolecules. This results in inhibition of vital biochemical processes such as protein synthesis, DNA, RNA, and cell wall synthesis, leading to bacterial cell death. It is bactericidal in urine at therapeutic concentrations but does not reach effective tissue levels outside the urinary tract, which is why it is not used for kidney-level infections. (1) (2)
What Nitrofurantoin is used for
Urinary tract infections (acute, uncomplicated)
Urinary tract infections (acute, uncomplicated) (2)
Urinary tract infections (prophylaxis)
Urinary tract infections (prophylaxis) (2)
Cystitis
Cystitis (2)
Before taking Nitrofurantoin
Do not take / not appropriate for
- Contraindicated in patients with severe renal impairment (CrCl <30 mL/min), history of nitrofurantoin-induced jaundice or hepatic dysfunction, hypersensitivity to nitrofurantoin, and in neonates under 1 month. (Contraindication) (2)
Tell your clinician about
(2)How to take Nitrofurantoin
- General Instructions: Take nitrofurantoin exactly as prescribed by your healthcare provider. Do not skip doses or stop early, even if you feel better.. Adult Dosing: For uncomplicated UTIs: 100 mg orally twice daily for 5–7 days (Macrobid) or 50–100 mg four times daily (Macrodantin).. Pediatric Dosing: Children over 1 month: 5–7 mg/kg/day in divided doses every 6 hours. Not recommended for infants under 1 month.. Administration: Take with food or milk to minimize stomach upset. Swallow capsules/tablets whole with a full glass of water.. When To Stop: Complete the full prescribed course unless your doctor tells you to stop. If you develop severe side effects or signs of an allergic reaction, seek medical advice promptly; let the clinician you see advise on whether to continue or stop the medication.. Storage: Store at room temperature (20–25°C/68–77°F), away from moisture and heat. Keep out of reach of children.
- This page does not provide a dose calculator. Dosing must follow the prescriber, pharmacist, or product label.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (2)
Missed dose
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 resume your regular schedule. Do not double up to make up for a missed dose.
Overdose
In case of overdose, seek emergency medical attention or contact a poison control center immediately. Symptoms may include nausea, vomiting, and neurological symptoms. Supportive care is the mainstay of treatment. (2)
Side effects
Side effects and their urgency vary; report severe, persistent, or concerning symptoms to a healthcare professional.
Nausea
Incidence: Reported in the clinician-authored database; frequency not established
Vomiting
Incidence: Reported in the clinician-authored database; frequency not established
Diarrhea
Incidence: Reported in the clinician-authored database; frequency not established
Headache
Incidence: Reported in the clinician-authored database; frequency not established
Dizziness
Incidence: Reported in the clinician-authored database; frequency not established
Peripheral neuropathy
Incidence: Reported in the clinician-authored database; frequency not established
Pulmonary fibrosis
Incidence: Reported in the clinician-authored database; frequency not established
Hepatotoxicity
Incidence: Reported in the clinician-authored database; frequency not established
Serious warnings
Chronic pulmonary reactions (interstitial pneumonitis or pulmonary fibrosis) can develop insidiously, typically after 6 or more months of therapy, and may cause permanent lung impairment — serious
Symptoms: Chronic pulmonary reactions (interstitial pneumonitis or pulmonary fibrosis) can develop insidiously, typically after 6 or more months of therapy, and may cause permanent lung impairment. Hepatotoxicity is rare but serious, and fatalities have been reported; liver function should be monitored with prolonged use. Peripheral neuropathy may become severe or irreversible, especially with renal impairment, anemia, diabetes, or vitamin B deficiency. May cause hemolytic anemia in patients with G6PD deficiency (more common in Black patients and those of Mediterranean or Near Eastern descent). Use with caution in elderly patients due to increased risk of side effects.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Contraindicated in patients with a creatinine clearance below 60 mL/min or clinically significant elevated serum creatinine, or with anuria/oliguria (this is a stricter threshold than an earlier draft's CrCl <30 mL/min figure, which did not match the FDA label) — serious
Symptoms: Contraindicated in patients with a creatinine clearance below 60 mL/min or clinically significant elevated serum creatinine, or with anuria/oliguria (this is a stricter threshold than an earlier draft's CrCl <30 mL/min figure, which did not match the FDA label). Also contraindicated in pregnancy at term (38-42 weeks), during labor, or when delivery is imminent, due to the risk of hemolytic anemia in the newborn; in neonates under 1 month of age; in patients with a history of nitrofurantoin-induced cholestatic jaundice or hepatic dysfunction; and in known hypersensitivity to nitrofurantoin. Not indicated for kidney infections (pyelonephritis) or perinephric abscess. Use with caution in patients with G6PD deficiency, pulmonary disease, hepatic dysfunction, and elderly patients.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Recorded interactions | Nitrofurantoin may interact with antacids containing magnesium trisilicate (reducing absorption), probenecid and sulfinpyrazone (increasing risk of toxicity), and certain vaccines. Inform your healthcare provider about all medications and supplements you are taking. | (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy
No animal-study evidence of fetal harm was seen at doses up to 6 times the human dose, and the FDA label states nitrofurantoin should be used during pregnancy only if clearly needed. It is specifically CONTRAINDICATED at term (38-42 weeks gestation), during labor, or when delivery is imminent, because of the risk of hemolytic anemia in the newborn. Discuss timing and alternatives with your obstetric provider. (2)
Breastfeeding
Ask your healthcare provider before use while breastfeeding, particularly if the infant has or may have G6PD deficiency. (2)
Children
For children over 1 month of age: 5-7 mg/kg per 24 hours, given in FOUR divided doses (approximately every 6 hours) for acute infection; for long-term suppressive therapy, doses as low as 1 mg/kg per 24 hours in one or two divided doses may be adequate. NOTE: this corrects an earlier draft that stated a twice-daily (every-12-hours) schedule with a 200 mg/day cap, which did not match the FDA label's four-times-daily regimen. Not recommended in infants under 1 month of age. (2)
Renal_impairment
Contraindicated at creatinine clearance below 60 mL/min or with clinically significant elevated serum creatinine, and in anuria/oliguria, due to reduced efficacy and increased toxicity risk (an earlier draft stated a CrCl <30 mL/min threshold, which was corrected to match the FDA label). Also contraindicated in patients with a history of nitrofurantoin-induced cholestatic jaundice or hepatic dysfunction; use with caution in other hepatic impairment. (2)
Hepatic_impairment
Contraindicated at creatinine clearance below 60 mL/min or with clinically significant elevated serum creatinine, and in anuria/oliguria, due to reduced efficacy and increased toxicity risk (an earlier draft stated a CrCl <30 mL/min threshold, which was corrected to match the FDA label). Also contraindicated in patients with a history of nitrofurantoin-induced cholestatic jaundice or hepatic dysfunction; use with caution in other hepatic impairment. (2)
Monitoring
(2)Storage
Store at 20-25 degC (68-77 degF), in a tight, light-resistant container with a child-resistant closure, away from moisture and heat. Keep out of reach of children.
Professional information
Clinician-facing context only. This section does not replace current product labeling.
General (US FDA label) — adults
Indication: Urinary tract infections (acute, uncomplicated), confined to the bladder
Dose summary: 100 mg orally twice daily for 5-7 days (Macrobid) or 50-100 mg four times daily (Macrodantin); long-term suppression 50-100 mg at bedtime. Not indicated for pyelonephritis/perinephric abscess.
Renal context: Contraindicated at CrCl <60 mL/min or clinically significant elevated serum creatinine, and in anuria/oliguria. (2)
General (US FDA label) — children over 1 month
Indication: Urinary tract infections, acute treatment and long-term suppression
Dose summary: Acute: 5-7 mg/kg/24h in four divided doses (about every 6 hours). Suppression: as low as 1 mg/kg/24h in one or two divided doses.
Renal context: Contraindicated at CrCl <60 mL/min or clinically significant elevated serum creatinine, and in anuria/oliguria. (2)
Frequently asked questions
What is nitrofurantoin used for?
Nitrofurantoin is primarily used to treat and prevent urinary tract infections (UTIs) caused by susceptible bacteria. It is not effective for infections outside the urinary tract.
How quickly does nitrofurantoin work?
Most people begin to feel better within 1–2 days of starting nitrofurantoin, but it is important to complete the full course as prescribed.
Can I take nitrofurantoin if I have kidney problems?
Nitrofurantoin is contraindicated at a creatinine clearance below 60 mL/min or with significantly elevated serum creatinine, due to reduced effectiveness and increased risk of side effects. Your healthcare provider will check your kidney function before prescribing it.
Is nitrofurantoin safe during pregnancy?
Nitrofurantoin may be used earlier in pregnancy only if clearly needed, but it is contraindicated at term (38-42 weeks), during labor, or when delivery is imminent, because of the risk of hemolytic anemia in the newborn. Your obstetric provider will advise on timing.
What should I do if I develop a rash or breathing problems while taking nitrofurantoin?
Seek immediate medical attention, as these may be signs of a serious allergic reaction; let the clinician you see advise on whether to continue or stop the medication.
Can I drink alcohol while taking nitrofurantoin?
Alcohol does not directly interact with nitrofurantoin, but it may worsen side effects such as stomach upset. Consult your healthcare provider for personalized advice.
What foods or medicines should I avoid while taking nitrofurantoin?
Avoid antacids containing magnesium trisilicate and inform your doctor about all other medications you are taking to prevent interactions.
What happens if I take too much Nitrofurantoin?
Taking too much Nitrofurantoin can lead to symptoms such as severe nausea, vomiting, and diarrhea. In rare cases, it may cause neurological issues or liver damage. If you suspect an overdose, seek immediate emergency medical attention. Do not attempt to induce vomiting unless advised by a healthcare professional.
What is the mechanism of action of Nitrofurantoin?
Nitrofurantoin is reduced by bacterial flavoproteins to reactive intermediates that inactivate or alter bacterial ribosomal proteins and other macromolecules. This results in inhibition of vital biochemical processes such as protein synthesis, DNA, RNA, and cell wall synthesis, leading to bacterial cell death. It is bactericidal in urine at therapeutic concentrations but does not reach effective tissue levels outside the urinary tract, which is why it is not used for kidney-level infections. (1) (2)
What is the generic name of Nitrofurantoin?
The generic name is Nitrofurantoin. It is sold under brand names including Macrodantin, Macrobid, Nifuran, Nitrofur SR, Urofurantoin, Teva-Nitrofurantoin.
What class of drug is Nitrofurantoin?
Nitrofurantoin is classed as: Antibiotic (Nitrofuran derivative).
References
- Nitrofurantoin clinician-authored medicine recordMedGuideGlobal · United States · accessed 2026-08-06 · source 1
- MACRODANTIN (nitrofurantoin macrocrystals) capsules — prescribing informationU.S. Food and Drug Administration · United States · accessed 2026-08-06 · source 2
- NITROFURANTOIN CAPSULE [PREFERRED PHARMACEUTICALS INC.] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 3
- Nitrofurantoin — FDA approval record (Drugs@FDA ANDA216385)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 4
- Nitrofurantoin — RxNorm normalized drug concept (RXCUI 221129)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 5
Brand names by country
Single-ingredient Nitrofurantoin names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
United States
- nitrofurantoin macrocrystals50 mg, 100 mg, 25 mg · northstar rxllc
- Nitrofurantion100 mg, 25 mg, 50 mg · sun pharmaceutical industries, inc.
- Nitrofurantion Macrocrystals50 mg, 100 mg · proficient rx lp
Canada
- MACROBID