Two medicines, side by side
Clarithromycin vs metronidazole
Clarithromycin and metronidazole are both labeled for bacterial infections. Drugs@FDA records approvals of clarithromycin since 1991 and of metronidazole since 1963. Pharmacies paid $0.466 per clarithromycin 500 mg tablet 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, clarithromycin is a macrolide antimicrobial and metronidazole a nitroimidazole antimicrobial.
Check it at the source: the clarithromycin FDA label on DailyMed (effective April 9, 2026); the metronidazole FDA label on DailyMed (effective September 3, 2024).
Highlights of the clarithromycin record
Clarithromycin (Biaxin) · label of April 9, 2026
Used for
From the label: indicationsClarithromycin is a macrolide antimicrobial indicated for mild to moderate infections caused by designated, susceptible bacteria in the following: Acute Bacterial Exacerbation of Chronic Bronchitis in Adults (1.1) Acute Maxillary Sinusitis (1.2) Community-Acquired Pneumonia (1.3) Pharyngitis/Tonsillitis (1.4) Uncomplicated Skin and Skin Structure Infections (1.5) Acute Otitis Media in Pediatric Patients (1.6) […]
On the market
- Earliest approval on file
- October 31, 1991
- Generic labelers
- 26 labelers
- Pharmacy cost
- $0.466 per tablet
Supply and safety
- Shortage
- No current entry
- Recalls
- 3
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 (Clarithromycin label of April 9, 2026, Metronidazole label of September 3, 2024); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do clarithromycin and metronidazole differ on the record?
In FDA's classes, clarithromycin is a macrolide antimicrobial and metronidazole a nitroimidazole antimicrobial.
Half-life, in each label's words: Clarithromycin, “The elimination half-life of clarithromycin was about 3 hours to 4 hours with 250 mg administered every 12 hours but …”; Metronidazole, “The elimination half-life, measured during the first 3 days of life, was inversely related to gestational age.”
Only the metronidazole label carries a boxed warning.
Generics: clarithromycin since 2004; metronidazole since 1984 (Drugs@FDA).
| Clarithromycin | Metronidazole | |
|---|---|---|
| Labeled for | Bacterial infections, Acid reflux and ulcers | Bacterial infections |
| Pharmacologic class | Macrolide Antimicrobial | Nitroimidazole Antimicrobial |
| How it works (label) | Clarithromycin is a macrolide antimicrobial drug [see Microbiology (12.4) ]. | n/a |
| Half-life (label) | The elimination half-life of clarithromycin was about 3 hours to 4 hours with 250 mg administered every 12 hours but increased to 5 hours to 7 hours with 500 mg administered every 8 hours to 12 hours. | The elimination half-life, measured during the first 3 days of life, was inversely related to gestational age. |
| Earliest approval on file (Drugs@FDA) | October 31, 1991 | July 18, 1963 |
| First generic approved | May 25, 2004 | December 6, 1984 |
| Generic labelers (NDC) | 26 labelers | 55 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.466 per tablet (Clarithromycin 500 mg tablet) | $0.102 per tablet (Metronidazole 250 mg tablet) |
| 12-month price change | +6% | +10% |
| Boxed warning | No | Yes |
| Shortage now | No current entry | In shortage |
| Recalls recorded | 3 | 7 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 34,134 | 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 clarithromycin
- every medicine labeled for the same conditions