Clarithromycin is part of first-line H. pylori eradication regimens in regions where clarithromycin resistance is below 15%. Maastricht VI/Florence 2022 recommends triple therapy PPI + amoxicillin 1000 mg twice daily + clarithromycin 500 mg twice daily for 14 days. When resistance exceeds 15%, the first-line regimen is switched to bismuth-containing quadruple therapy without clarithromycin. The Russian Ministry of Health clinical recommendation "Gastritis and duodenitis in adults" (ID 708, 2024) lists clarithromycin in first-line regimens where susceptibility is confirmed.

In Russia, H. pylori resistance to clarithromycin varies from 10% to 30% across regions. Susceptibility testing or use of local resistance maps before starting therapy is preferable.

Sources

Practical notes

Timing and administration

Standard tablets 250-500 mg are taken twice daily; the extended-release form (Biaxin XL 500 mg) is taken once daily with food. Taking with meals increases bioavailability of the extended-release form and reduces dyspepsia. The interval between standard-form doses is kept at 12 hours.

Dose titration

Course duration depends on indication: community-acquired pneumonia – 5-7 days for standard form, 7 days for extended-release; H. pylori eradication – 14 days; acute bacterial sinusitis – 10 days. At eGFR below 30 mL/min/1.73 m², the dose is halved or the dosing interval extended. In elderly patients, the starting dose is unchanged, but renal function and ECG are monitored.

Monitoring

Before starting therapy and after 3-4 days, an ECG is checked when concurrent QT-prolonging agents are used or in patients with heart disease. Serum potassium and magnesium are corrected before starting the course. For courses longer than 14 days, ALT, AST, and total bilirubin are checked. Auditory symptoms (tinnitus, hearing loss) are an indication for immediate discontinuation.

Special situations

Clarithromycin is a potent CYP3A4 and P-glycoprotein inhibitor. Concomitant medications are reviewed before prescribing: statins (simvastatin, lovastatin), direct oral anticoagulants, tacrolimus, cyclosporine, ticagrelor, colchicine, PDE-5 inhibitors, hepatically metabolized benzodiazepines, and warfarin. Many combinations require discontinuation or substitution of the co-medication during the course. In patients on hemodialysis, no supplementary dose is given after the session.

Common myths

Myth: "a macrolide is a mild antibiotic, take it for any cough". Fact: in acute viral bronchitis and uncomplicated URI, clarithromycin does not shorten the illness and increases the risk of pneumococcal resistance.

Myth: "after the course you need a probiotic to restore the flora". Fact: routine probiotic supplementation for antibiotic-associated diarrhea prevention does not have unanimous support in international guidelines; the decision is individual.

Myth: "safer than beta-lactams in pregnancy". Fact: the opposite – amoxicillin has a more complete safety record in the first trimester; clarithromycin is chosen when alternatives are not feasible.

Drug–drug interactions

5 pairs found. Sorted from critical to minor.

Critical

colchicine

Antigout agents

Mechanism

Сильная ингибиция CYP3A4 и P-gp кларитромицином приводит к токсическим концентрациям колхицина. Описаны летальные исходы.

Management

Сочетание противопоказано у пациентов с почечной или печеночной недостаточностью. У остальных – снизить дозу колхицина на 50–75%.

Sources

FDA: Colcrys (colchicine) prescribing information (2022)

Pair details →

Critical

simvastatin

HMG-CoA reductase inhibitors (statins)

Mechanism

Сильная ингибиция CYP3A4 кларитромицином увеличивает концентрацию симвастатина до 10 раз. Высокий риск рабдомиолиза и острой почечной недостаточности.

Management

Сочетание противопоказано. Прерывать прием симвастатина на курс кларитромицина либо заменить антибиотик на азитромицин (без CYP3A4-ингибиции).

Sources

FDA: Zocor (simvastatin) prescribing information (2020)

Pair details →

Major

amiodarone

Class III antiarrhythmics (Vaughan Williams)

Mechanism

Аддитивное удлинение QT-интервала + ингибиция CYP3A4 кларитромицином увеличивает экспозицию амиодарона.

Management

Сочетание избегать. Если без него нельзя – ЭКГ исходно и через 48 часов, контроль электролитов (K, Mg).

Sources

AHA: Drugs that Prolong QT and TdP – AHA Scientific Statement (2020)

Pair details →

Major

Ciclosporin

Immunosuppressants. Calcineurin inhibitors

Mechanism

Кларитромицин ингибирует CYP3A4 и P-gp, концентрация циклоспорина может удвоиться. Риск нефротоксичности.

Management

Контроль уровня циклоспорина через 3–5 дней. Снизить дозу на 25–50% или заменить антибиотик на азитромицин.

Sources

FDA: Sandimmune (cyclosporine) prescribing information (2021)

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Major

haloperidol

First-generation antipsychotics. Butyrophenone derivatives

Mechanism

Аддитивное удлинение QT + ингибиция CYP3A4 повышает концентрацию галоперидола.

Management

ЭКГ-контроль исходно и через 48 часов. У пожилых и при сердечной патологии – избегать.

Sources

AHA: Drugs that Prolong QT and TdP – AHA Scientific Statement (2020)

Pair details →

Frequently asked

What is clarithromycin used for?

clarithromycin is evaluated for the following indications with varying evidence strength: Community-acquired pneumonia (evidence tier A), Helicobacter pylori eradication (evidence tier A), Infective endocarditis prophylaxis in low-risk patients (evidence tier D). See the full indication matrix with dosing and citations above on this page.

What are the side effects of clarithromycin?

Common side effects of clarithromycin (≥ 1 in 100): Nausea, abdominal discomfort, diarrhea, Taste disturbance, metallic taste, Headache, Transient elevation of liver transaminases. See the Safety section for uncommon and serious reactions.

Is clarithromycin safe during pregnancy?

FDA category C. FDA category C. In animal studies at doses 2-17 times the human dose, pregnancy loss and malformations were observed. Human data are limited, and clarithromycin is not used in the first trimester when alternatives (amoxicillin, azithromycin) exist. The decision is made jointly with the obstetrician-gynecologist for severe infection when the benefit outweighs the risk.

Is clarithromycin compatible with breastfeeding?

Clarithromycin passes into breast milk in small amounts. LactMed classifies it as conditionally compatible with breastfeeding. Monitor the infant for diarrhea, thrush, and rash. Alternatives are preferred when available.

Who should not take clarithromycin?

clarithromycin is contraindicated in: Hypersensitivity to macrolides in history; Concurrent use with QT-prolonging agents (amiodarone, quinidine, sotalol, class IA and III antipsychotics); Concurrent use with simvastatin, lovastatin, ticagrelor, ranolazine, colchicine in renal or hepatic impairment; Concurrent use with ergot alkaloids (ergotamine, dihydroergotamine); Severe hepatic impairment with cholestasis or jaundice during prior macrolide course. Full list in the Safety section.

a macrolide is a mild antibiotic, take it for any cough

in acute viral bronchitis and uncomplicated URI, clarithromycin does not shorten the illness and increases the risk of pneumococcal resistance.

after the course you need a probiotic to restore the flora

routine probiotic supplementation for antibiotic-associated diarrhea prevention does not have unanimous support in international guidelines; the decision is individual.

safer than beta-lactams in pregnancy

the opposite – amoxicillin has a more complete safety record in the first trimester; clarithromycin is chosen when alternatives are not feasible.

clarithromycin

Mechanism of action

Indications

Community-acquired pneumonia

Helicobacter pylori eradication

Infective endocarditis prophylaxis in low-risk patients

Acute viral bronchitis

Practical notes

Timing and administration

Dose titration

Monitoring

Special situations

Common myths

Drug–drug interactions

colchicine

simvastatin

amiodarone

Ciclosporin

haloperidol

Safety

Contraindications

Serious adverse effects

Common adverse effects

Uncommon adverse effects

PregnancyFDA C

Breastfeeding

Frequently asked