Two medicines, side by side
Nitrofurantoin vs metronidazole
Nitrofurantoin and metronidazole are both labeled for bacterial infections. Drugs@FDA records approvals of nitrofurantoin since 1953 and of metronidazole since 1963. Pharmacies paid $0.165 per nitrofurantoin mcr 50 mg capsule and $0.102 per metronidazole 250 mg tablet (NADAC, October 7, 2026); the strengths differ, so the two prices are not like for like. Metronidazole's other strengths are brand-only: $2.60 per mL (Likmez 500 mg/5 mL suspension). In FDA's classes, nitrofurantoin is a nitrofuran antibacterial and metronidazole a nitroimidazole antimicrobial.
Check it at the source: the nitrofurantoin FDA label on DailyMed (effective June 24, 2026); the metronidazole FDA label on DailyMed (effective September 3, 2024).
Highlights of the nitrofurantoin record
Nitrofurantoin (Macrobid) · label of June 24, 2026
Used for
From the label: indicationsNitrofurantoin capsules (monohydrate/macrocrystals) are indicated only for the treatment of acute uncomplicated urinary tract infections (acute cystitis) caused by susceptible strains of Escherichia coli or Staphylococcus saprophyticus. Nitrofurantoin is not indicated for the treatment of pyelonephritis or perinephric abscesses. […]
On the market
- Earliest approval on file
- February 6, 1953
- Generic labelers
- 47 labelers
- Pharmacy cost
- $0.165 per capsule
Supply and safety
- Shortage
- A presentation being discontinued
- Recalls
- 13
Highlights of the metronidazole record
Metronidazole (Flagyl) · label of September 3, 2024
Metronidazole has been shown to be carcinogenic in mice and rats (see PRECAUTIONS ). Unnecessary use of the drug should be avoided. Its use should be reserved for the conditions described in the INDICATIONS AND USAGE section below.
Used for
From the label: indicationsSymptomatic Trichomoniasis. Metronidazole tablets are indicated for the treatment of T. vaginalis infection in females and males when the presence of the trichomonad has been confirmed by appropriate laboratory procedures (wet smears and/or cultures). Asymptomatic Trichomoniasis. […]
On the market
- Earliest approval on file
- July 18, 1963
- Generic labelers
- 55 labelers
- Pharmacy cost
- $0.102 per tablet
Supply and safety
- Shortage
- In shortage
- Recalls
- 7
Source: FDA drug labels via openFDA (Nitrofurantoin label of June 24, 2026, Metronidazole label of September 3, 2024); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do nitrofurantoin and metronidazole differ on the record?
In FDA's classes, nitrofurantoin is a nitrofuran antibacterial and metronidazole a nitroimidazole antimicrobial.
Only the metronidazole label carries a boxed warning.
Generics: nitrofurantoin since 1970; metronidazole since 1984 (Drugs@FDA).
| Nitrofurantoin | Metronidazole | |
|---|---|---|
| Labeled for | Urinary tract infections, Bacterial infections | Bacterial infections |
| Pharmacologic class | Nitrofuran Antibacterial | Nitroimidazole Antimicrobial |
| How it works (label) | Mechanism of Action The mechanism of the antimicrobial action of nitrofurantoin is unusual among antibacterials. | n/a |
| Half-life (label) | n/a | The elimination half-life, measured during the first 3 days of life, was inversely related to gestational age. |
| Earliest approval on file (Drugs@FDA) | February 6, 1953 | July 18, 1963 |
| First generic approved | September 30, 1970 | December 6, 1984 |
| Generic labelers (NDC) | 47 labelers | 55 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.165 per capsule (Nitrofurantoin mcr 50 mg capsule) | $0.102 per tablet (Metronidazole 250 mg tablet) |
| 12-month price change | -12% | +10% |
| Boxed warning | No | Yes |
| Shortage now | A presentation being discontinued | In shortage |
| Recalls recorded | 13 | 7 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 22,755 | 63,553 |
| DEA schedule | none | none |
Source: Drugs@FDA, FDA NDC Directory, CMS NADAC of October 7, 2026, FDA shortages and recalls, FAERS via openFDA (FDA files October 8, 2026)
What next?
- Alternatives to nitrofurantoin
- every medicine labeled for the same conditions