Nitrofurantoin
MACROBID
What it isUrinary antiseptic whose reactive intermediates damage bacterial DNA; uncomplicated lower urinary infection.
Why this oneIt concentrates in urine with little systemic or microbiome exposure, so resistance remains relatively uncommon.
What limits itDo not use for pyelonephritis or bacteremia; poor renal function prevents urinary delivery. Long courses risk lung, liver and nerve toxicity.
FDA-approved for
- UTIs (~1953)
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Urinary tract infection | Adults & peds >12 yr | 100 mg BID | 100 mg BID | 100 mg BID x7 days |
Renal Contraindicated if CrCl <60 mL/min or significant renal impairment (anuria/oliguria)
Hepatic Contraindicated with prior nitrofurantoin-associated cholestatic jaundice/hepatic dysfunction; otherwise Undefined
Instructions
- Take with food
Contraindications
- Anuria, oliguria, or significant renal impairment (CrCl <60 mL/min)
- Pregnancy at term (38-42 wk), labor/delivery, or imminent labor (neonatal hemolytic anemia risk)
- Neonates under 1 month of age
- Prior cholestatic jaundice/hepatic dysfunction associated with nitrofurantoin
Cautions
- Acute, subacute, or chronic pulmonary hypersensitivity reactions (may be irreversible)
- Peripheral neuropathy — may be severe/irreversible; higher risk with renal impairment, anemia, diabetes, B deficiency
- Hepatotoxicity (hepatitis, cholestatic jaundice, hepatic necrosis)
- Hemolytic anemia (G6PD deficiency)
- Pseudomembranous colitis
Adverse reactions
- Nausea
- Headache
- Flatulence
- Pulmonary hypersensitivity reactions
- Peripheral neuropathy
- Hepatic reactions
Pregnancy Contraindicated at term (38-42 wk), during labor/delivery, or when labor imminent (neonatal hemolytic anemia risk)
Lactation Undefined
NO BOXED WARNINGS
Principal riskPulmonary toxicity with long-term use; ineffective in pyelonephritis
Cost, est. cash$10–$500/month
Generic entry2011
Classes and tags
Clinical profile
Legacy pregnancy categoryB
Defining liabilityAllergy, gastrointestinal effects and agent-specific renal, hepatic, hematologic or interaction risks.
Mechanism of action: Nitrofurantoin ballicule
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