AntibioticsAntibioticA class of compounds that kill bacteria or stop their growth; divided by mechanism into subgroups (e.g. cell-wall, protein-synthesis or DNA inhibitors).
Amoxicillin vs Ciprofloxacin vs Doxycycline
The table compares the compounds’ key data from their entry pages. Open each compound’s full entry for details. Educational content, not medical advice.
 Amoxicillin | Ciprofloxacin | Doxycycline | |
|---|---|---|---|
| What it is | Broad-spectrum β-lactam penicillin-class antibiotic. WHO Essential Medicines, one of the most prescribed antibiotics worldwide. Standard first-line for otitis media, sinusitis, pneumonia, UTI, dental prophylaxis, and H. pylori eradication. | Fluoroquinolone antibiotic (Bayer Cipro). UTI, GI + complex Gram-negative infections. FDA boxed warning: tendon rupture + peripheral neuropathy. | Tetracycline antibiotic (Vibramycin). Lyme, malaria prevention, acne, chlamydia, atypical pneumonia. 100 mg standard. |
| ATC codeATC codeThe WHO Anatomical Therapeutic Chemical code that classifies drugs by organ system and mechanism. | J01CA04 | J01MA02 | J01AA02 |
| Prescription | Prescription only (Rx), antibiotic stewardship | Prescription only (Rx), stewardship protocol | Prescription only (Rx) |
| MechanismMechanism of actionThe molecular pathway by which a compound acts in the body (e.g. which receptor or enzyme it binds). | β-lactam, PBP transpeptidase inhibitor, bactericidal | DNA gyrase and topoisomerase IV inhibitor (fluoroquinolone) | 30S ribosome-binding protein synthesis inhibitor (tetracycline, bacteriostatic) |
| Half-lifeHalf-lifeThe time for the compound’s plasma concentration to fall by half; indicates how fast it clears and how often it is dosed. | 1-1.5 h (renal function-dependent) | ~4 h (twice-daily dosing) | 18-22 h (once or twice daily) |
| OnsetOnsetThe time from dosing until a measurable effect appears. | 1-2 h (plasma peak), 24-72 h (clinical response) | 24–48 h (clinical response) | 24-48 h (clinical response) |
| Full entry | Open → | Open → | Open → |
What it is
AmoxicillinBroad-spectrum β-lactam penicillin-class antibiotic. WHO Essential Medicines, one of the most prescribed antibiotics worldwide. Standard first-line for otitis media, sinusitis, pneumonia, UTI, dental prophylaxis, and H. pylori eradication.
CiprofloxacinFluoroquinolone antibiotic (Bayer Cipro). UTI, GI + complex Gram-negative infections. FDA boxed warning: tendon rupture + peripheral neuropathy.
DoxycyclineTetracycline antibiotic (Vibramycin). Lyme, malaria prevention, acne, chlamydia, atypical pneumonia. 100 mg standard.
ATC codeATC codeThe WHO Anatomical Therapeutic Chemical code that classifies drugs by organ system and mechanism.
AmoxicillinJ01CA04
CiprofloxacinJ01MA02
DoxycyclineJ01AA02
Prescription
AmoxicillinPrescription only (Rx), antibiotic stewardship
CiprofloxacinPrescription only (Rx), stewardship protocol
DoxycyclinePrescription only (Rx)
MechanismMechanism of actionThe molecular pathway by which a compound acts in the body (e.g. which receptor or enzyme it binds).
Amoxicillinβ-lactam, PBP transpeptidase inhibitor, bactericidal
CiprofloxacinDNA gyrase and topoisomerase IV inhibitor (fluoroquinolone)
Doxycycline30S ribosome-binding protein synthesis inhibitor (tetracycline, bacteriostatic)
Half-lifeHalf-lifeThe time for the compound’s plasma concentration to fall by half; indicates how fast it clears and how often it is dosed.
Amoxicillin1-1.5 h (renal function-dependent)
Ciprofloxacin~4 h (twice-daily dosing)
Doxycycline18-22 h (once or twice daily)
OnsetOnsetThe time from dosing until a measurable effect appears.
Amoxicillin1-2 h (plasma peak), 24-72 h (clinical response)
Ciprofloxacin24–48 h (clinical response)
Doxycycline24-48 h (clinical response)