Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
Amoxicillin-Clavulanate vs AMCILL
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Amoxicillin inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), inhibiting transpeptidation and autolysin inhibitors. Clavulanate is a beta-lactamase inhibitor that binds to and inactivates beta-lactamases, protecting amoxicillin from hydrolysis.
Ampicillin is a beta-lactam antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), leading to cell lysis and death.
Acute bacterial sinusitis,Acute otitis media,Community-acquired pneumonia,Urinary tract infections,Skin and skin structure infections,Intra-abdominal infections,Lower respiratory tract infections,Diabetic foot infections,Prophylaxis of infection following surgery (off-label)
Infections of the respiratory tract,Infections of the genitourinary tract,Meningitis,Septicemia,Endocarditis,Gastrointestinal infections,Prophylaxis of bacterial endocarditis
500 mg/125 mg orally every 8 hours or 875 mg/125 mg orally every 12 hours; intravenous: 1 g/0.2 g every 8 hours.
250-500 mg orally every 8 hours or 500 mg every 12 hours; for severe infections, up to 1 g every 6 hours intravenously.
Amoxicillin: ~1-1.3 hours in adults with normal renal function; Clavulanate: ~1 hour. Both prolonged in renal impairment (amoxicillin up to 7-20 hours with Cr Cl <10 m L/min).
1-1.5 hours in normal renal function; prolonged to 7-10 hours in anuria.
Amoxicillin is partially metabolized via hydrolysis of the beta-lactam ring to inactive penicilloic acid, minor hepatic metabolism; excreted primarily unchanged renally. Clavulanate is extensively metabolized in the liver, primarily to metabolites excreted in urine and feces.
Partially metabolized by hydrolysis; primarily excreted unchanged in urine via renal tubular secretion and glomerular filtration.
Amoxicillin: ~60% renal as unchanged drug via glomerular filtration and tubular secretion; Clavulanate: ~30-50% renal as metabolites and unchanged, remainder fecal. Approximately 50-70% of total dose excreted renally within 6 hours.
Renal: 60-80% unchanged; biliary: less than 10%; fecal: small amount.
Amoxicillin: ~17% bound to serum protein (primarily albumin); Clavulanate: ~25% bound to albumin.
20% bound, primarily to albumin.
Amoxicillin: Vd ~0.3-0.4 L/kg; clavulanate: Vd ~0.3 L/kg. Distributes well into interstitial fluid, tissues, and bone; limited CNS penetration (10-20% of serum levels) unless inflamed meninges.
0.3 L/kg; indicates distribution into extracellular fluid.
Oral: 80-90% for both components; food does not significantly affect absorption (note: clavulanate is better absorbed with food, extended-release tab with food).
Oral: 50-70% (variable, reduced by food); IM: nearly 100%.
Cr Cl 30-50 m L/min: 500 mg/125 mg orally every 12 hours; Cr Cl 10-29 m L/min: 500 mg/125 mg orally every 24 hours; Cr Cl <10 m L/min: 500 mg/125 mg orally every 24 hours, supplement after dialysis.
For Cr Cl 30-50 m L/min: administer every 12 hours; for Cr Cl 10-29 m L/min: administer every 18-24 hours; for Cr Cl <10 m L/min: administer every 24 hours.
No specific adjustment recommended; use with caution in severe hepatic impairment (Child-Pugh C).
No specific adjustments recommended for Child-Pugh A or B; use caution in severe hepatic impairment (Child-Pugh C) with monitoring.
3 months to 40 kg: 25-45 mg/kg/day of amoxicillin component in 2-3 divided doses; >40 kg: adult dosing.
Children >1 month: 25-50 mg/kg/day orally divided every 8 hours; for severe infections, up to 100 mg/kg/day IV divided every 6 hours. Maximum dose: 2 g/day.
Adjust based on renal function; initiate with lower end of dosing due to age-related renal decline.
No specific dose adjustment required; monitor renal function and adjust based on creatinine clearance.
None
No FDA black box warning.
Serious hypersensitivity reactions (anaphylaxis) can occur,Clostridium difficile-associated diarrhea (CDAD) risk,Hepatic dysfunction, including hepatitis and cholestatic jaundice, especially in elderly and patients with prior therapy,Renal impairment requires dose adjustment,Potential for superinfection with prolonged therapy
Hypersensitivity reactions including anaphylaxis,Clostridioides difficile-associated diarrhea,Superinfection,Risk of seizures with high doses or renal impairment,Use caution in patients with mononucleosis (high risk of rash)
History of hypersensitivity reaction to any penicillin,History of cholestatic jaundice or hepatic dysfunction associated with amoxicillin-clavulanate,Infectious mononucleosis (risk of erythematous rash)
Hypersensitivity to ampicillin, penicillins, or any component of the formulation,Infections caused by beta-lactamase-producing organisms
May be taken with food to reduce GI irritation. No significant food interactions. Avoid high-fat meals if taking extended-release formulation (fat increases absorption variability).
Food does not significantly affect absorption; may be taken with or without meals. Avoid alcohol: may increase risk of disulfiram-like reaction (rare).
FDA Category B. No evidence of teratogenicity in animal studies; human data do not indicate increased risk of major birth defects. However, use only when clearly needed in pregnancy, especially during first trimester. Theoretical risk of neonatal kernicterus if used near term due to bilirubin displacement from albumin.
FDA Pregnancy Category B. No evidence of teratogenicity in animal studies. First trimester: Not associated with major birth defects. Second and third trimesters: Use only if clearly needed; potential for altered gut flora and diarrhea in neonate.
Compatible with breastfeeding. Excreted into breast milk in low amounts (M/P ratio not established; amoxicillin milk concentration ~ 0.5-1% of maternal serum). No adverse effects reported in nursing infants. Consider monitoring for diarrhea or rash.
Ampicillin is excreted in breast milk in low concentrations (M/P ratio approximately 0.2). Compatible with breastfeeding; monitor infant for diarrhea or rash.
No routine dose adjustment in pregnancy despite increased renal clearance and expanded plasma volume. Standard adult dosing is appropriate unless GFR <30 m L/min. Monitor for therapeutic efficacy in pregnancy-related infections (e.g., UTIs, chorioamnionitis).
Increased renal clearance during pregnancy may require higher doses to maintain therapeutic levels. Standard dosing is usually adequate for most indications; consider monitoring serum levels in severe infections.
Administer with food to reduce GI upset. Monitor for rash, especially in patients with mononucleosis (EBV). Dose adjustment required for Cr Cl <30 m L/min. High dose (2000 mg amoxicillin) provides adequate coverage for penicillin-resistant S. pneumoniae. Avoid in penicillin allergy; cross-reactivity with cephalosporins is low but possible.
AMCILL (ampicillin) is a broad-spectrum penicillinase-sensitive penicillin. Use caution in patients with renal impairment; dose adjustment required for Cr Cl <30 m L/min. Monitor for hypersensitivity reactions, especially in patients with cephalosporin allergy. IV administration may cause phlebitis; rotate infusion sites. Not effective against penicillinase-producing organisms including Staphylococcus aureus.
Take with food or milk to minimize stomach upset.,Complete the full course even if you feel better.,Shake oral suspension well before each use.,Use backup contraception if on oral contraceptives.,Contact doctor if rash, watery diarrhea, or signs of liver problems (yellowing skin, dark urine).,Do not take if allergic to penicillin or cephalosporins.
Take exactly as prescribed; complete full course even if you feel better.,Notify your doctor if you develop rash, hives, or difficulty breathing.,May cause diarrhea; contact your doctor if severe or bloody.,Take with a full glass of water; avoid acidic beverages like orange juice.,Inform your doctor if you are pregnant, breastfeeding, or taking oral contraceptives (ampicillin may reduce efficacy).
"Amoxicillin may reduce the metabolism of Indinavir via inhibition of CYP3A4, leading to increased plasma concentrations of Indinavir. This can elevate the risk of Indinavir-related toxicities such as nephrolithiasis, hepatotoxicity, and gastrointestinal intolerance. Patients may experience exacerbated adverse effects without a corresponding increase in antiviral efficacy."
"Amoxicillin may inhibit the CYP3A4-mediated metabolism of nicardipine, a calcium channel blocker, leading to increased plasma concentrations of nicardipine. This can potentiate vasodilation and negative chronotropic effects, resulting in an increased risk of hypotension, bradycardia, and peripheral edema. Patients, especially those with pre-existing cardiovascular conditions, should be monitored for enhanced antihypertensive effects and adverse reactions when these drugs are coadministered."
"Amoxicillin may inhibit the metabolism of bortezomib through competitive inhibition of cytochrome P450 enzymes, particularly CYP3A4 and CYP2C19, potentially leading to increased bortezomib exposure. This interaction could result in enhanced toxicity of bortezomib, including peripheral neuropathy, myelosuppression, and gastrointestinal adverse effects. Clinicians should monitor for signs of bortezomib toxicity when amoxicillin is coadministered, especially in patients with pre-existing hepatic impairment or other risk factors."
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about Amoxicillin-Clavulanate vs AMCILL, answered by our medical review team.
Amoxicillin-Clavulanate is a Penicillin Antibiotic + Beta-Lactamase Inhibitor that works by Amoxicillin inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), inhibiting transpeptidation and autolysin inhibitors. Clavulanate is a beta-lactamase inhibitor that binds to and inactivates beta-lactamases, protecting amoxicillin from hydrolysis.. AMCILL is a Penicillin Antibiotic that works by Ampicillin is a beta-lactam antibiotic that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), leading to cell lysis and death.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between Amoxicillin-Clavulanate and AMCILL depend on the specific clinical indication. These are agents from distinct pharmacological classes and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of Amoxicillin-Clavulanate is: 500 mg/125 mg orally every 8 hours or 875 mg/125 mg orally every 12 hours; intravenous: 1 g/0.2 g every 8 hours.. The standard adult dose of AMCILL is: 250-500 mg orally every 8 hours or 500 mg every 12 hours; for severe infections, up to 1 g every 6 hours intravenously.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between Amoxicillin-Clavulanate and AMCILL in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. Amoxicillin-Clavulanate is classified as Category C. FDA Category B. No evidence of teratogenicity in animal studies; human data do not indicate increased risk of major birth defects. However, use only when clearly needed in pregnanc. AMCILL is classified as Category C. FDA Pregnancy Category B. No evidence of teratogenicity in animal studies. First trimester: Not associated with major birth defects. Second and third trimesters: Use only if clearl. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.