Two medicines, side by side
Metronidazole vs amoxicillin
Metronidazole and amoxicillin are both labeled for bacterial infections. Drugs@FDA records approvals of metronidazole since 1963 and of amoxicillin since 1974. Pharmacies paid $0.102 per metronidazole 250 mg tablet and $0.0788 per amoxicillin 500 mg capsule (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, metronidazole is a nitroimidazole antimicrobial and amoxicillin a penicillin-class antibacterial.
Check it at the source: the metronidazole FDA label on DailyMed (effective September 3, 2024); the amoxicillin FDA label on DailyMed (effective February 22, 2024).
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 amoxicillin record
Amoxicillin (Amoxil) · label of February 22, 2024
Used for
From the label: indicationsAdults and Pediatric Patients • Upper Respiratory Tract Infections of the Ear, Nose, and Throat Amoxicillin is indicated in the treatment of infections due to susceptible (ONLY β-lactamase–negative) isolates of Streptococcus species. (α- and β-hemolytic isolates only), Streptococcus pneumoniae, Staphylococcus spp. , or Haemophilus influenzae. […]
On the market
- Earliest approval on file
- January 18, 1974
- Generic labelers
- 38 labelers
- Pharmacy cost
- $0.0788 per capsule
Supply and safety
- Shortage
- No current entry
- Recalls
- 12
Source: FDA drug labels via openFDA (Metronidazole label of September 3, 2024, Amoxicillin label of February 22, 2024); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do metronidazole and amoxicillin differ on the record?
In FDA's classes, metronidazole is a nitroimidazole antimicrobial and amoxicillin a penicillin-class antibacterial.
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.”; Amoxicillin, “Metabolism and Excretion The half-life of amoxicillin is 61.3 minutes.”
Only the metronidazole label carries a boxed warning.
Generics: metronidazole since 1984; amoxicillin since 1974 (Drugs@FDA).
| Metronidazole | Amoxicillin | |
|---|---|---|
| Labeled for | Bacterial infections | Bacterial infections, Acid reflux and ulcers |
| Pharmacologic class | Nitroimidazole Antimicrobial | Penicillin-class Antibacterial |
| How it works (label) | n/a | Amoxicillin is an 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. | Metabolism and Excretion The half-life of amoxicillin is 61.3 minutes. |
| Earliest approval on file (Drugs@FDA) | July 18, 1963 | January 18, 1974 |
| First generic approved | December 6, 1984 | December 9, 1974 |
| Generic labelers (NDC) | 55 labelers | 38 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.102 per tablet (Metronidazole 250 mg tablet) | $0.0788 per capsule (Amoxicillin 500 mg capsule) |
| 12-month price change | +10% | -12% |
| Boxed warning | Yes | No |
| Shortage now | In shortage | No current entry |
| Recalls recorded | 7 | 12 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 63,553 | 75,926 |
| 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