Clarithromycin; Uses, Dosage, Side effects, Drug Interactions

Last updated: February 7, 2026Reviewed date: February 7, 2026Reading time: 6 min read
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Clarithromycin is a semisynthetic 14-membered ring macrolide antibiotic. Clarithromycin binds to the 50S ribosomal subunit and inhibits RNA-dependent protein synthesis in susceptible organisms. Clarithromycin has been shown to eradicate gastric MALT (mucosa-associated lymphoid tissue) lymphomas, presumably due to the eradication of tumorigenic Helicobacter pylori infection. This agent also acts as...

For severe symptoms, danger signs, pregnancy, child illness, or sudden worsening, seek urgent medical care.

বাংলা রোগী নোট এখনো যোগ করা হয়নি। পোস্ট এডিটরে “RX Bangla Patient Mode” বক্স থেকে সহজ বাংলা সারাংশ যোগ করুন।

এই তথ্য শিক্ষা ও সচেতনতার জন্য। এটি ডাক্তারি পরীক্ষা, রোগ নির্ণয় বা প্রেসক্রিপশনের বিকল্প নয়।

Article Summary

Clarithromycin is a semisynthetic 14-membered ring macrolide antibiotic. Clarithromycin binds to the 50S ribosomal subunit and inhibits RNA-dependent protein synthesis in susceptible organisms. Clarithromycin has been shown to eradicate gastric MALT (mucosa-associated lymphoid tissue) lymphomas, presumably due to the eradication of tumorigenic Helicobacter pylori infection. This agent also acts as a biological response modulator, possibly inhibiting angiogenesis and tumor growth through alterations in growth factor expression Clarithromycin, a semisynthetic macrolide...

Key Takeaways

  • This article explains Mechanism of action of Clarithromycin in simple medical language.
  • This article explains Indications of Clarithromycin in simple medical language.
  • This article explains Contra-Indications of Clarithromycin in simple medical language.
  • This article explains Dosage of Cethromycin in simple medical language.
Educational health guideWritten for patient understanding and clinical awareness.
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Emergency safety firstUrgent warning signs are highlighted below.

Seek urgent medical care if you notice

These warning signs are general safety guidance. Local emergency numbers and clinical judgment should always come first.

  • Severe symptoms, breathing difficulty, fainting, confusion, or rapidly worsening illness.
  • New weakness, severe pain, high fever, or symptoms after a serious injury.
  • Any symptom that feels urgent, unusual, or unsafe for the patient.
1

Emergency now

Use emergency care for severe, sudden, rapidly worsening, or life-threatening symptoms.

2

See a doctor

Book a professional medical evaluation if symptoms persist, worsen, recur often, affect daily activities, or occur in a high-risk patient.

3

Learn safely

Use this article to understand possible causes, tests, treatment options, prevention, and questions to ask your clinician.

Clarithromycin is a semisynthetic 14-membered ring macrolide bacterial infections. সহজ বাংলা: ব্যাকটেরিয়ার সংক্রমণের ওষুধ।" data-rx-term="antibiotic" data-rx-definition="An antibiotic is a medicine used to treat bacterial infections. সহজ বাংলা: ব্যাকটেরিয়ার সংক্রমণের ওষুধ।">antibiotic. Clarithromycin binds to the 50S ribosomal subunit and inhibits RNA-dependent protein synthesis in susceptible organisms. Clarithromycin has been shown to eradicate gastric MALT (mucosa-associated lymphoid tissue) lymphomas, presumably due to the eradication of tumorigenic Helicobacter pylori infection. This agent also acts as a biological response modulator, possibly inhibiting angiogenesis and tumor growth through alterations in growth factor expression

Clarithromycin, a semisynthetic macrolide bacterial infections. সহজ বাংলা: ব্যাকটেরিয়ার সংক্রমণের ওষুধ।" data-rx-term="antibiotic" data-rx-definition="An antibiotic is a medicine used to treat bacterial infections. সহজ বাংলা: ব্যাকটেরিয়ার সংক্রমণের ওষুধ।">antibiotic derived from erythromycin, inhibits bacterial protein synthesis by binding to the bacterial 50S ribosomal subunit. Binding inhibits peptidyl transferase activity and interferes with amino acid translocation during the translation and protein assembly process. Clarithromycin may be bacteriostatic or bactericidal depending on the organism and drug concentration.

Mechanism of action of Clarithromycin

Clarithromycin is first metabolized to 14-OH clarithromycin, which is active and works synergistically with its parent compound. Like other macrolides, it then penetrates bacteria cell wall and reversibly binds to domain V of the 23S ribosomal RNA of the 50S subunit of the bacterial ribosome, blocking translocation of aminoacyl transfer-RNA and polypeptide synthesis. Clarithromycin also inhibits the hepatic microsomal CYP3A4 isoenzyme and P-glycoprotein, an energy-dependent drug efflux pump

Indications of Clarithromycin

  • Dental Abscess
  • Sinusitis
  • Bronchitis
  • Bacterial Endocarditis Prevention
  • Follicular Lymphoma
  • Helicobacter Pylori Infection
  • Legionella Pneumonia
  • Mycobacterium avium-intracellulare,
  • Mycoplasma Pneumonia
  • Nongonococcal Urethritis
  • Otitis Media
  • Pertussis
  • Pharyngitis
  • Pneumonia
  • Skin and Structure Infection
  • Skin or Soft Tissue Infection
  • Strep Throat
  • Tonsillitis/Pharyngitis
  • Toxoplasmosis
  • Upper Respiratory Tract Infection
  • Acute Bacterial Exacerbation of Chronic Bronchitis
  • Acute maxillary sinusitis
  • Bacterial Infections
  • Bartonellosis
  • Community-Acquired Pneumonia
  • Duodenal ulcer caused by helicobacter pylori
  • Infective Endocarditis
  • Lyme Disease
  • Mycobacterial Infection
  • Otitis Media (OM)
  • Streptococcal Pharyngitis
  • Streptococcal tonsillitis
  • Uncomplicated skin and subcutaneous tissue bacterial infection
  • Investigated for use/treatment in bacterial infection, pediatric indications, and pneumonia.
  • You should not take clarithromycin if you are allergic to other macrolides or the ingredients in the tablets which include microcrystalline cellulose, croscarmelose sodium, magnesium stearate and povidon
  • Clarithromycin should not be used in people with a history of cholestatic jaundice and/or liver dysfunction associated with prior clarithromycin use.
  • or if you have hypokalaemia (low blood potassium)
  • Use of clarithromycin with the following medications: cisapride, pimozide, astemizole, terfenadine, ergotamine, ticagrelor, ranolazine or dihydroergotamine is not recommended.
  • It should not be used with colchicine in people with kidney or liver impairment.
  • Concomitant use with cholesterol medications such as lovastatin or simvastatin.
  • Hypersensitivity to clarithromycin or any component of the product, erythromycin, or any macrolide antibiotics.
  • QT prolongation or ventricular cardiac arrhythmias, including torsade de pointes.

Contra-Indications of Clarithromycin

  • Clostridium difficile infection
  • Low amount of magnesium in the blood
  • Low amount of potassium in the blood
  • Myasthenia Gravis
  • Coronary artery disease
  • Rapid Ventricular Heartbeat
  • Very Rapid Heartbeat – Torsades de Pointes
  • Slow Heartbeat
  • Prolonged QT interval on EKG
  • Abnormal EKG with QT changes from Birth
  • infection, or irritation, often causing pain, swelling, heat, or redness. সহজ বাংলা: শরীরের প্রদাহ; ব্যথা, ফোলা বা লালভাব হতে পারে।" data-rx-term="inflammation" data-rx-definition="Inflammation is the body’s response to injury, infection, or irritation, often causing pain, swelling, heat, or redness. সহজ বাংলা: শরীরের প্রদাহ; ব্যথা, ফোলা বা লালভাব হতে পারে।">Inflammation of the Liver with Stoppage of Bile Flow
  • Chronic kidney disease stage 3A (moderate)
  • Chronic kidney disease stage 3B (moderate)
  • Chronic kidney disease stage 5 (failure)
  • Allergies to Macrolide Antibiotics

Dosage of Cethromycin

Strengths: 250 mg; 500 mg; 125 mg/5 mL; 250 mg/5 mL

Tonsillitis/Pharyngitis

  • Immediate-release: 250 mg orally every 12 hours for 10 days

Sinusitis

  • Immediate-release: 500 mg orally every 12 hours for 14 days
  • Extended-release: 1000 mg orally every 24 hours for 14 days

Bronchitis

Immediate-release

  • Due to H influenzae: 500 mg orally every 12 hours for 7 to 14 days
  • Due to H parainfluenzae: 500 mg orally every 12 hours for 7 days
  • Due to M catarrhalis or S pneumoniae: 250 mg orally every 12 hours for 7 to 14 days

Extended-release

  • 1000 mg orally every 24 hours for 7 days

Pneumonia

Immediate-release

  • Due to H influenzae: 250 mg orally every 12 hours for 7 days
  • Due to S pneumoniae or Chlamydophila pneumoniae: 250 mg orally every 12 hours for 7 to 14 days

Extended-release

  • 1000 mg orally every 24 hours for 7 days

Mycoplasma Pneumonia

Immediate-release

  • 250 mg orally every 12 hours for 7 to 14 days

Extended-release

  • 1000 mg orally every 24 hours for 7 days

Skin and Structure Infection

Immediate-release

  • 250 mg orally every 12 hours for 7 to 14 days

Helicobacter pylori Infection

Triple therapy
  • In combination with lansoprazole and amoxicillin: Clarithromycin 500 mg orally every 12 hours for 10 to 14 days
  • In combination with omeprazole and amoxicillin: Clarithromycin 500 mg orally every 12 hours for 10 days

Dual therapy

  • In combination with omeprazole: Clarithromycin 500 mg orally every 8 hours for 14 days
  • In combination with ranitidine bismuth citrate: Clarithromycin 500 mg orally every 8 to 12 hours for 14 days

Bacterial Endocarditis Prophylaxis

American Heart Association (AHA) recommendations

  • Immediate-release: 500 mg orally as a single dose 30 to 60 minutes before procedure

Legionella Pneumonia

Some experts recommend

  • Immediate-release: 500 mg orally every 12 hours

Pertussis

US CDC recommendations

  • Immediate-release: 500 mg orally every 12 hours for 7 days

Tonsillitis/Pharyngitis

Immediate-release

  • 6 months or older: 7.5 mg/kg orally every 12 hours for 10 days
  • Maximum dose: 500 mg/dose

Pediatric Dose for Sinusitis

Immediate-release

  • 6 months or older: 7.5 mg/kg orally every 12 hours for 10 days
  • Maximum dose: 500 mg/dose

Pediatric Dose for Pneumonia

Immediate-release

  • 6 months or older: 7.5 mg/kg orally every 12 hours for 10 days
  • Maximum dose: 500 mg/dose

Pediatric Dose for Otitis Media

Immediate-release

  • 6 months or older: 7.5 mg/kg orally every 12 hours for 10 days
  • Maximum dose: 500 mg/do

Side Effects of Clarithromycin

The most common

Common

Less common

Rare

Drug Interactions of Clarithromycin

Clarithromycin may interact with following drugs, supplements,& may change the efficasy of drugs

Clarithromycin increases blood levels of sildenafil (Viagra, Revatio), tadalafil(Cialis, Adcirca), vardenafil (Levitra), theophylline (Theolair), and carbamazepine (Tegretol), which can increase the side effects of these drugs.Ritonavir (Norvir) and atazanavir (Reyataz) increase blood levels of clarithromycin.Efavirenz (Sustiva), nevirapine (Viramune), and rifampin (Rifadin) decrease blood levels of clarithromycin.

Itraconazole (Sporanox) and saquinavir (Invirase) may increase blood levels of clarithromycin, while clarithromycin increases blood levels of both drugs. Abnormal heartbeats may occur when clarithromycin is combined with some drugs, such as amiodarone (Cordarone), quinidine (Quinidex), amitriptyline(Elavil), fluconazole (Diflucan), citalopram (Celexa), trazodone (Oleptro), or disopyramide (Norpace).

Pregnancy & Lactation of Clarithromycin

Pregnancy

Clarithromycin should not be used during pregnancy, especially the first 3 months of pregnancy, unless there is no appropriate alternative therapy. If you become pregnant while taking this medication, contact your doctor.

Breast-feeding

This medication passes into breast milk. If you are a breastfeeding mother and are taking clarithromycin, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

References

Clarithromycin; Uses, Dosage, Side effects, Drug Interactions

Doctor visit helper

Prepare before seeing a doctor

A simple rural-patient checklist to help you explain symptoms clearly, ask better questions, and avoid unsafe self-treatment.

Safety note: This is not a prescription or diagnosis. For severe symptoms, pregnancy danger signs, children with serious illness, chest pain, breathing difficulty, stroke-like weakness, or major injury, seek urgent care.

Which doctor may help?

Start with a registered doctor or the nearest qualified health center.

What to tell the doctor

  • Write when the problem started and how it changed.
  • Bring old prescriptions, investigation reports, and current medicines.
  • Write allergies, pregnancy status, diabetes, kidney/liver disease, and major past illnesses.
  • Bring one family member if the patient is weak, elderly, confused, or a child.

Questions to ask

  • What is the most likely cause of my symptoms?
  • Which danger signs mean I should go to hospital quickly?
  • Which tests are necessary now, and which can wait?
  • How should I take medicines safely and what side effects should I watch for?
  • When should I come for follow-up?

Tests to discuss

  • Vital signs: temperature, pulse, blood pressure, oxygen saturation
  • Basic physical examination by a clinician
  • CBC, urine test, blood sugar, or imaging only when clinically needed

Avoid these mistakes

  • Do not use antibiotics, steroid tablets/injections, or strong painkillers without proper medical advice.
  • Do not hide pregnancy, kidney disease, ulcer, allergy, or blood thinner use.
  • Do not delay emergency care when danger signs are present.

Medicine safety and first-aid guide

This section is for patient education only. It does not replace a doctor, pharmacist, or emergency care.

Safe first steps

  • Drink safe fluids and monitor temperature.
  • In dengue-prone areas, discuss CBC and platelet count when fever persists or warning signs appear.
  • Use tepid sponging for high fever discomfort; avoid ice-cold bathing.

OTC medicine safety

  • For fever, common fever medicine may be discussed with a clinician or pharmacist.
  • Avoid aspirin/ibuprofen-like medicines in suspected dengue unless a doctor says it is safe.

Avoid these mistakes

  • Do not start antibiotics without a proper medical decision.
  • Do not use steroid tablets or injections casually for quick relief.
  • Do not delay emergency care because of home remedies.

Get urgent help if

  • Fever with breathing difficulty, confusion, repeated vomiting, bleeding, severe weakness, stiff neck, or dehydration needs urgent care.
Medicine names, dose, and timing must be decided by a qualified clinician or pharmacist after checking age, pregnancy, allergy, other diseases, and current medicines.

For rural patients and family caregivers

Patient health record and symptom diary

Write your symptoms, medicines already taken, test results, and questions before visiting a doctor. This note stays on your device unless you print or copy it.

Doctor to discuss: Medicine doctor / pediatrician for children / qualified clinician
Tests to discuss with doctor
  • Temperature chart and hydration assessment
  • CBC with platelet count if fever persists or dengue/other infection is possible
  • Urine test, malaria/dengue tests, chest evaluation, or blood culture only when clinically indicated
Questions to ask
  • What is the most likely cause of my symptoms?
  • Which warning signs mean I should go to emergency care?
  • Which tests are really needed now?
  • Which medicines are safe for my age, pregnancy status, allergy, kidney/liver/stomach condition, and current medicines?
  • Do I need antibiotics, or is this more likely viral?

Emergency warning signs such as chest pain, severe breathing difficulty, sudden weakness, confusion, severe dehydration, major injury, or loss of bladder/bowel control need urgent medical care. Do not wait for online information.

Safe pathway to proper treatment

Care roadmap for: Clarithromycin; Uses, Dosage, Side effects, Drug Interactions

Use this simple roadmap to understand the next safe steps. It is educational and does not replace examination by a doctor.

Go to emergency care if you notice:
  • Severe or rapidly worsening symptoms
  • Breathing difficulty, chest pain, fainting, confusion, severe weakness, major injury, or severe dehydration
Doctor / service to discuss: Qualified healthcare provider; specialist depends on symptoms and examination.
  1. Step 1

    Check danger signs first

    If danger signs are present, seek emergency care and do not wait for online information.

  2. Step 2

    Record the symptom story

    Write when symptoms started, severity, medicines already taken, allergies, pregnancy status, and test results.

  3. Step 3

    Visit a qualified clinician

    A doctor, nurse, or qualified healthcare provider can examine you and decide which tests or treatment are needed.

  4. Step 4

    Do only useful tests

    Do tests after clinical assessment. Avoid unnecessary tests, random antibiotics, or repeated medicines without diagnosis.

  5. Step 5

    Follow up and return early if worse

    If symptoms worsen, new warning signs appear, or treatment is not helping, return for review quickly.

Rural patient practical tips
  • Take a written symptom diary and all previous prescriptions/test reports.
  • Do not hide medicines already taken, even herbal or over-the-counter medicines.
  • Ask which warning signs mean urgent referral to hospital.

This roadmap is for education. A real diagnosis and treatment plan requires history, examination, and clinical judgment.

RX Patient Help

Ask a health question safely

Write your symptom story. A health professional or site editor can review it before any answer is prepared. This box is not for emergency care.

Emergency first: Severe chest pain, breathing trouble, unconsciousness, stroke signs, severe injury, heavy bleeding, or rapidly worsening symptoms need urgent local medical care now.

Frequently Asked Questions

Is this article a replacement for a doctor?

No. It is educational content only. Patients should consult a qualified clinician for diagnosis and treatment.

When should I seek urgent care?

Seek urgent care for severe symptoms, rapidly worsening condition, breathing difficulty, severe pain, neurological changes, or any emergency warning sign.

References

Add references, clinical guidelines, textbooks, journal articles, or trusted medical sources here. You can edit this area from the RX Article Professional Blocks panel.

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