Amoxicillin

Aminopenicillin·Infectious Diseases - Penicillins

Community-acquired pneumonia, acute otitis media, sinusitis, dental infections

PBSBETA-LACTAMAmoxil, Cilamox250 mgS4+1

Max Dose

3 g/day

Half-life

1 h

Rash

COMMON

Anaphylaxis

CRITICAL

Rapid Summary

Overview

Foundational, broad-spectrum aminopenicillin. Highly effective for susceptible respiratory, ENT, and dental pathogens. Excellent oral bioavailability.

Maximum Dose

Max 3 g/day (standard) or 4 g/day (in high-dose specialist regimens).

Clinical Focus

Differentiate a true IgE-mediated allergy (hives/anaphylaxis) from a benign childhood viral rash before withholding.

Bottom Line

Amoxicillin is a first-line broad-spectrum penicillin for respiratory, urinary, and dental infections, but causes a characteristic maculopapular rash in EBV/glandular fever that is not true allergy.

Formulation & Access

Brand Names

Amoxil, Cilamox

Oral Routes

Capsules (250 mg, 500 mg). Oral liquid (125 mg/5mL, 250 mg/5mL).

Prescribing & PBS

Unrestricted General Benefit (S4).

Indications & Use

Primary

PBSTGA

Community-acquired pneumonia, acute otitis media, sinusitis, dental infections.

Clinical Place

First-line oral step-down for susceptible respiratory infections.

Quick reference

Class & Role

Aminopenicillin — Foundational, broad-spectrum aminopenicillin.

Route / Formulation

Capsules (250 mg, 500 mg). Oral liquid (125 mg/5mL, 250 mg/5mL). (Amoxil, Cilamox)

Usual Dose & Max

PO 500 mg to 1 g TDS. Max 3 g/day (standard) or 4 g/day (in high-dose specialist regimens).

Key Indication Doses

CAP / Otitis Media: PO 500 mg to 1 g TDS. H. Pylori Eradication: PO 1 g BD (as part of triple therapy). Endocarditis Prophylaxis: PO 2 g STAT 60 mins prior to dental procedure.

Best Uses

Amoxicillin is a first-line broad-spectrum penicillin for respiratory, urinary, and dental infections, but causes a characteristic maculopapular rash in EBV/glandular fever that is not true allergy.

Avoid / Cautions

History of Type 1 (IgE) penicillin hypersensitivity. Pregnancy Category A.

Key Risks

Immunological: IgE-mediated anaphylaxis, angioedema. MODERATE — Non-allergic maculopapular rash. Gastrointestinal: Diarrhea, nausea. MODERATE — C. difficile infection. Renal: Crystalluria at massive IV doses.

Key Interactions

Allopurinol (Concurrent use massively increases the risk of a severe skin rash). Methotrexate (Penicillins reduce renal clearance of MTX, risking fatal bone marrow toxicity).

Monitoring

Observe for 30 mins after first dose for signs of anaphylaxis. Check eGFR to guide dosing frequency.

Clinical Pearl

Giving amoxicillin to a patient with infectious mononucleosis (glandular fever) guarantees a severe, full-body maculopapular rash in 90% of cases. This is NOT a true allergy, but it will be labeled as one forever.

Access

Amoxil, Cilamox250 mg

Brand: Amoxil, Cilamox
Formulation: Capsules (250 mg, 500 mg)

Amoxicillin

Aminopenicillin·Infectious Diseases - Penicillins

Community-acquired pneumonia, acute otitis media, sinusitis, dental infections

PBSBETA-LACTAMAmoxil, Cilamox250 mgS4+1

Max Dose

3 g/day

Half-life

1 h

Rash

COMMON

Anaphylaxis

CRITICAL

Rapid Summary

Overview

Foundational, broad-spectrum aminopenicillin. Highly effective for susceptible respiratory, ENT, and dental pathogens. Excellent oral bioavailability.

Maximum Dose

Max 3 g/day (standard) or 4 g/day (in high-dose specialist regimens).

Clinical Focus

Differentiate a true IgE-mediated allergy (hives/anaphylaxis) from a benign childhood viral rash before withholding.

Bottom Line

Amoxicillin is a first-line broad-spectrum penicillin for respiratory, urinary, and dental infections, but causes a characteristic maculopapular rash in EBV/glandular fever that is not true allergy.

Formulation & Access

Brand Names

Amoxil, Cilamox

Oral Routes

Capsules (250 mg, 500 mg). Oral liquid (125 mg/5mL, 250 mg/5mL).

Prescribing & PBS

Unrestricted General Benefit (S4).

Indications & Use

Primary

PBSTGA

Community-acquired pneumonia, acute otitis media, sinusitis, dental infections.

Clinical Place

First-line oral step-down for susceptible respiratory infections.

Quick reference

Class & Role

Aminopenicillin — Foundational, broad-spectrum aminopenicillin.

Route / Formulation

Capsules (250 mg, 500 mg). Oral liquid (125 mg/5mL, 250 mg/5mL). (Amoxil, Cilamox)

Usual Dose & Max

PO 500 mg to 1 g TDS. Max 3 g/day (standard) or 4 g/day (in high-dose specialist regimens).

Key Indication Doses

CAP / Otitis Media: PO 500 mg to 1 g TDS. H. Pylori Eradication: PO 1 g BD (as part of triple therapy). Endocarditis Prophylaxis: PO 2 g STAT 60 mins prior to dental procedure.

Best Uses

Amoxicillin is a first-line broad-spectrum penicillin for respiratory, urinary, and dental infections, but causes a characteristic maculopapular rash in EBV/glandular fever that is not true allergy.

Avoid / Cautions

History of Type 1 (IgE) penicillin hypersensitivity. Pregnancy Category A.

Key Risks

Key Interactions

Allopurinol (Concurrent use massively increases the risk of a severe skin rash). Methotrexate (Penicillins reduce renal clearance of MTX, risking fatal bone marrow toxicity).

Monitoring

Observe for 30 mins after first dose for signs of anaphylaxis. Check eGFR to guide dosing frequency.

Clinical Pearl

Access

Amoxil, Cilamox250 mg

Brand: Amoxil, Cilamox
Formulation: Capsules (250 mg, 500 mg)