Two medicines, side by side
Metronidazole vs tetracycline
Metronidazole and tetracycline are both labeled for bacterial infections. Drugs@FDA records approvals of metronidazole since 1963 and of tetracycline since 1953. Pharmacies paid $0.102 per metronidazole 250 mg tablet and $0.247 per tetracycline 250 mg capsule (NADAC, October 7, 2026). Metronidazole's other strengths are brand-only: $2.60 per mL (Likmez 500 mg/5 mL suspension). In FDA's classes, metronidazole is a nitroimidazole antimicrobial and tetracycline a tetracycline-class antimicrobial.
Check it at the source: the metronidazole FDA label on DailyMed (effective September 3, 2024); the tetracycline FDA label on DailyMed (effective March 18, 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 tetracycline record
Tetracycline (Achromycin) · label of March 18, 2025
Used for
From the label: indicationsTo reduce the development of drug-resistant bacteria and maintain the effectiveness of tetracycline hydrochloride and other antibacterial drugs, tetracycline hydrochloride should be used only to treat infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. […]
On the market
- Earliest approval on file
- November 19, 1953
- Generic labelers
- 10 labelers
- Pharmacy cost
- $0.247 per capsule
Supply and safety
- Shortage
- No current entry
- Recalls
- 2
Source: FDA drug labels via openFDA (Metronidazole label of September 3, 2024, Tetracycline label of March 18, 2025); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do metronidazole and tetracycline differ on the record?
In FDA's classes, metronidazole is a nitroimidazole antimicrobial and tetracycline a tetracycline-class antimicrobial.
Only the metronidazole label carries a boxed warning.
Generics: metronidazole since 1984; tetracycline since 1954 (Drugs@FDA).
| Metronidazole | Tetracycline | |
|---|---|---|
| Labeled for | Bacterial infections | Bacterial infections |
| Pharmacologic class | Nitroimidazole Antimicrobial | Tetracycline-class Antimicrobial |
| How it works (label) | n/a | n/a |
| Half-life (label) | The elimination half-life, measured during the first 3 days of life, was inversely related to gestational age. | n/a |
| Earliest approval on file (Drugs@FDA) | July 18, 1963 | November 19, 1953 |
| First generic approved | December 6, 1984 | September 17, 1954 |
| Generic labelers (NDC) | 55 labelers | 10 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.102 per tablet (Metronidazole 250 mg tablet) | $0.247 per capsule (Tetracycline 250 mg capsule) |
| 12-month price change | +10% | -65% |
| Boxed warning | Yes | No |
| Shortage now | In shortage | No current entry |
| Recalls recorded | 7 | 2 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 63,553 | 767 |
| 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