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Macrolide antibiotic

Clarithromycin (ENT Indications)

Brand names: Klaricid

Used in: Pneumonia Cellulitis & Skin Infection

Clarithromycin is a macrolide antibiotic used for respiratory and ENT infections, as part of Helicobacter pylori eradication, and as a penicillin alternative in some 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

Clarithromycin binds the bacterial 50S ribosomal subunit, inhibiting protein synthesis (bacteriostatic at usual concentrations).

Prescribing in practice

  • It is a strong CYP3A4 inhibitor with many important interactions — notably statins (myopathy risk), some DOACs, and other QT-prolonging drugs.
  • It can prolong the QT interval; use caution with other QT-prolonging agents and in electrolyte disturbance.
  • Reduce the dose in significant renal impairment.

Monitoring

Short courses need no routine monitoring; review interacting drugs (e.g. temporarily withholding certain statins) and consider ECG/electrolytes where QT risk is high.

Counselling the patient

  • Complete the course; gastrointestinal upset and a metallic taste are common.
  • Tell your clinician about all other medicines, as clarithromycin interacts with many.

Evidence & guidelines

Macrolides are recommended where a penicillin is unsuitable and within H. pylori eradication regimens, subject to local guidance and interaction checks.

Reference: PHE ENT 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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