Prescription ·Strong evidence ·Reviewed May 2026
A broad-spectrum penicillin antibiotic used to treat a wide variety of bacterial infections including otitis media, sinusitis, pharyngitis, lower respiratory tract infections, urinary tract infections, and H. pylori eradication (in combination). It is one of the most commonly prescribed antibiotics worldwide due to its favorable safety profile and efficacy against many gram-positive and some gram-negative organisms.
The bottom line
Evidence rating strong. Most-documented uses: treats streptococcal pharyngitis (strep throat), treats acute otitis media, treats acute bacterial sinusitis. 10 sources indexed (1998–2024), with 3 interaction records on file.
Core mechanism
Inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), which are transpeptidases essential for cross-linking peptidoglycan in the bacterial cell wall. This prevents the final transpeptidation step, weakening the cell wall and leading to osmotic lysis and bacterial death. Amoxicillin is bactericidal and effective against actively dividing organisms.9
Well absorbed orally (~90% bioavailability) regardless of food. Can be taken with or without food; food does not significantly affect absorption.5
Nutrients this medication can lower over time, and what to replace.
Broad-spectrum antibiotic exposure can suppress gut bacteria that synthesize menaquinones, lowering vitamin K availability in susceptible patients.
Probiotic supplementation during amoxicillin therapy reduces antibiotic-associated diarrhea and helps preserve gut microbiome diversity. Although amoxicillin causes less AAD than clindamycin or fluoroquinolones, the protective effect is still meaningful.
Recommendation: Take probiotics throughout your amoxicillin course, separated by at least 2 hours from each antibiotic dose. Continue for at least 1 week after the antibiotic ends.
Saccharomyces boulardii reduces antibiotic-associated diarrhea during amoxicillin therapy and is unaffected by the antibiotic because it is a yeast. It is particularly useful for patients with a history of AAD.
Recommendation: Take Saccharomyces boulardii throughout your amoxicillin course. Timing flexibility is greater than with bacterial probiotics. Continue for at least 1 week after the antibiotic ends.
Lactobacillus rhamnosus GG reduces antibiotic-associated diarrhea in patients on amoxicillin, with the strongest pediatric evidence among probiotic strains. Separation from antibiotic dosing preserves bacterial viability.
Recommendation: Take Lactobacillus rhamnosus throughout your amoxicillin course, separated by at least 2 hours from each antibiotic dose. Continue for at least 1 week after the antibiotic ends.
Numbered references. Citations throughout the page link here.
Systematic review found amoxicillin (often combined with metronidazole) as adjunctive therapy significantly improved periodontal treatment outcomes including probing depth reduction and clinical attachment gain compared to scaling alone.
Systematic review across WHO regions found amoxicillin resistance in H. pylori was relatively low (overall ~12%) compared to clarithromycin and metronidazole, supporting its continued use in first-line eradication regimens.
Calvet X, García N, López T et al.. A meta-analysis of short versus long therapy with a proton pump inhibitor, clarithromycin and either metronidazole or amoxycillin for treating Helicobacter pylori infection. Alimentary pharmacology & therapeutics. 2000
Gisbert JP, González L, Calvet X et al.. Proton pump inhibitor, clarithromycin and either amoxycillin or nitroimidazole: a meta-analysis of eradication of Helicobacter pylori. Alimentary pharmacology & therapeutics. 2000
Huang J, Hunt RH. The importance of clarithromycin dose in the management of Helicobacter pylori infection: a meta-analysis of triple therapies with a proton pump inhibitor, clarithromycin and amoxycillin or metronidazole. Alimentary pharmacology & therapeutics. 1999
de Ferranti SD, Ioannidis JP, Lau J et al.. Are amoxycillin and folate inhibitors as effective as other antibiotics for acute sinusitis? A meta-analysis. BMJ (Clinical research ed.). 1998
Pradillo-Gallego D, Manzano-Moreno FJ, Ocaña-Peinado FM et al.. Effects of clindamycin and amoxycillin as prophylaxis against early implant failure: double-blinded randomized clinical trial. Clinical oral investigations. 2024
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