How the dose is calculated
Clarithromycin is dosed in mg/kg/day, divided every 12 hours. The same weight-based dose is used whether treating a respiratory/skin infection alone or as one component of a combination regimen (with a proton-pump inhibitor and a second antibiotic) for H. pylori eradication — it's the accompanying drugs and course length that differ, not the clarithromycin dose itself.
Typical dosing by indication
| Indication | Dose | Frequency | Max |
|---|---|---|---|
| Standard | 15 mg/kg/day | every 12h (2×/day) | 1000 mg/day |
Clinical use
- Clarithromycin is used for respiratory tract infections, skin infections, and — combined with a proton-pump inhibitor and a second antibiotic (amoxicillin or metronidazole) — as part of triple therapy for Helicobacter pylori eradication.
- More acid-stable and generally better tolerated than erythromycin, with fewer GI side effects.
- Strong CYP3A4 inhibitor — review for interactions with other medications metabolised by this pathway, including some statins and calcium-channel blockers.
- Can prolong the QT interval — use caution with other QT-prolonging drugs or known arrhythmia risk.
Frequently asked questions
What is clarithromycin used for?
Clarithromycin is a macrolide antibiotic used for respiratory tract and skin infections, and as part of combination (triple) therapy with a proton-pump inhibitor and a second antibiotic to eradicate Helicobacter pylori.
Is the clarithromycin dose different for H. pylori treatment?
The weight-based clarithromycin dose itself is generally the same — what differs for H. pylori eradication is that it's combined with a proton-pump inhibitor and a second antibiotic, and given for a specific course length (commonly 7–14 days).
Does clarithromycin interact with other medicines?
Yes — it's a strong inhibitor of the CYP3A4 liver enzyme, so it can raise levels of many other drugs metabolised by that pathway, including some statins and calcium-channel blockers. Always review the full medication list before prescribing.
Is clarithromycin better tolerated than erythromycin?
Generally yes — clarithromycin causes less GI upset than erythromycin because it doesn't stimulate motilin receptors as strongly, and its twice-daily dosing is more convenient than erythromycin's four-times-daily schedule.
References
- Malfertheiner P, et al. Management of Helicobacter pylori Infection — Maastricht VI/Florence Consensus Report. Gut. 2022.
- British National Formulary for Children (BNFc) — Clarithromycin.
- Bradley JS, et al. PIDS/IDSA Community-Acquired Pneumonia Guideline. Clin Infect Dis. 2011.