Two medicines, side by side
Metronidazole vs azithromycin
Metronidazole and azithromycin are both labeled for bacterial infections. Drugs@FDA records approvals of metronidazole since 1963 and of azithromycin since 1991. Pharmacies paid $0.102 per metronidazole 250 mg tablet and $0.266 per azithromycin 250 mg tablet (NADAC, October 7, 2026). Metronidazole's other strengths are brand-only: $2.60 per mL (Likmez 500 mg/5 mL suspension). Azithromycin's other strengths are brand-only: $98.51 per mL (Azasite 1% eye drops). In FDA's classes, metronidazole is a nitroimidazole antimicrobial and azithromycin a macrolide antimicrobial.
Check it at the source: the metronidazole FDA label on DailyMed (effective September 3, 2024); the azithromycin FDA label on DailyMed (effective December 4, 2025).
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
Highlights of the azithromycin record
Azithromycin (Zithromax) · label of December 4, 2025
Used for
From the label: indicationsAzithromycin tablets are macrolide antibacterial drug indicated for the treatment of patients with mild to moderate infections caused by susceptible strains of the designated microorganisms in the specific conditions listed below. […]
On the market
- Earliest approval on file
- November 1, 1991
- Generic labelers
- 55 labelers
- Pharmacy cost
- $0.266 per tablet
Supply and safety
- Shortage
- A presentation being discontinued
- Recalls
- 11
Source: FDA drug labels via openFDA (Metronidazole label of September 3, 2024, Azithromycin label of December 4, 2025); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do metronidazole and azithromycin differ on the record?
In FDA's classes, metronidazole is a nitroimidazole antimicrobial and azithromycin a macrolide antimicrobial.
Half-life, in each label's words: Metronidazole, “The elimination half-life, measured during the first 3 days of life, was inversely related to gestational age.”; Azithromycin, “Elimination Plasma concentrations of azithromycin following single 500 mg oral and IV doses declined in a polyphasic …”
Only the metronidazole label carries a boxed warning.
Generics: metronidazole since 1984; azithromycin since 2005 (Drugs@FDA).
| Metronidazole | Azithromycin | |
|---|---|---|
| Labeled for | Bacterial infections | Bacterial infections |
| Pharmacologic class | Nitroimidazole Antimicrobial | Macrolide Antimicrobial |
| How it works (label) | n/a | Azithromycin is a macrolide antibacterial drug. [see Microbiology ( 12.4 )] |
| Half-life (label) | The elimination half-life, measured during the first 3 days of life, was inversely related to gestational age. | Elimination Plasma concentrations of azithromycin following single 500 mg oral and IV doses declined in a polyphasic pattern resulting in a mean apparent plasma clearance of 630 mL/min and terminal elimination half-life … |
| Earliest approval on file (Drugs@FDA) | July 18, 1963 | November 1, 1991 |
| First generic approved | December 6, 1984 | November 14, 2005 |
| Generic labelers (NDC) | 55 labelers | 55 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.102 per tablet (Metronidazole 250 mg tablet) | $0.266 per tablet (Azithromycin 250 mg tablet) |
| 12-month price change | +10% | -26% |
| Boxed warning | Yes | No |
| Shortage now | In shortage | A presentation being discontinued |
| Recalls recorded | 7 | 11 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 63,553 | 59,712 |
| 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 metronidazole
- every medicine labeled for the same conditions