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Antibiotic — Community-Acquired Pneumonia

Amoxicillin

Brand names: Amoxil

Amoxicillin is a broad-spectrum aminopenicillin widely used for respiratory tract infections such as community-acquired pneumonia and infective COPD exacerbations. This entry covers its respiratory indications.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

It inhibits bacterial cell-wall synthesis by binding penicillin-binding proteins, causing lysis of susceptible bacteria. Its spectrum includes common respiratory pathogens such as Streptococcus pneumoniae.

Prescribing in practice

  • It is contraindicated in patients with penicillin allergy and can cause anaphylaxis, so a clear allergy history must be taken before prescribing — the primary safety point.
  • It is ineffective against beta-lactamase-producing organisms and atypical pathogens, so choice should follow local antimicrobial guidance and severity assessment such as CRB-65.
  • Dose frequency should be reduced in significant renal impairment per current prescribing references, and a maculopapular rash is characteristic if given in glandular fever.

Monitoring

Review clinical response within the expected timeframe and watch for hypersensitivity, diarrhoea or signs of antibiotic-associated colitis.

Counselling the patient

  • Complete the full prescribed course even once you feel better.
  • Stop and seek urgent help if you develop a rash, swelling or breathing difficulty.
  • Report severe or persistent diarrhoea.

Evidence & guidelines

NICE and BTS guidance recommend amoxicillin as a first-line option for many community-acquired respiratory infections, reflecting its activity against typical pathogens.

Reference: NICE NG138 (CAP 2019); BTS CAP Guidelines 2009 (updated); PHE antimicrobial guidelines; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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