Clarithromycin – Macrolide antibiotic for respiratory and atypical infections.
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What is Clarithromycin?
Clarithromycin is a macrolide antibiotic effective against a wide range of bacterial infections, particularly respiratory tract infections. It’s often used as an alternative for people allergic to penicillin and is particularly effective against atypical bacteria.
Book an online consultation if you’re experiencing symptoms of a bacterial infection such as persistent cough, chest pain, or throat pain. Our GPs can assess your condition and determine if Clarithromycin is the right treatment for you.
What is Clarithromycin used for?
- Chest infections (pneumonia, bronchitis)
- Throat infections
- Sinusitis
- Skin and soft tissue infections
- Helicobacter pylori eradication (stomach ulcers)
- Atypical pneumonia
- Mycobacterial infections
How does Clarithromycin work?
A macrolide antibiotic that inhibits bacterial protein synthesis, preventing bacteria from growing and multiplying. Effective against both typical and atypical bacteria.
Dosage and Administration
Adults
250-500 mg twice daily, usually for 7-14 days depending on infection.
Children
7.5 mg per kg twice daily—GP will calculate appropriate dose based on weight.
Important Notes
- Can be taken with or without food.
- Take at evenly spaced intervals (every 12 hours).
- Modified-release tablets should be swallowed whole, not crushed.
- Complete the full course even if you feel better.
Side Effects
Common Side Effects
- Nausea and vomiting
- Diarrhoea
- Abdominal pain
- Altered taste (metallic taste)
- Headache
- Indigestion
Serious Side Effects
Seek immediate medical attention if you experience:
- Heart rhythm abnormalities (QT prolongation)
- Severe liver reactions
- Clostridioides difficile-associated diarrhoea
- Hearing loss (usually reversible)
- Severe allergic reactions
Important Warnings
- Tell your GP if you have heart problems or irregular heart rhythm.
- May worsen myasthenia gravis symptoms.
- Can interact with many medications—inform your GP of all medicines you take.
- Not recommended with certain heart medications or if you have low potassium/magnesium.
Drug Interactions
Tell your GP if you're taking any of the following medications:
- Warfarin—significantly increases bleeding risk.
- Statins (cholesterol medications)—increased risk of muscle problems.
- Digoxin—may increase digoxin levels.
- Theophylline—may increase theophylline toxicity.
- Ergot alkaloids—dangerous interaction, avoid completely.
- Many other medications—always check with your GP or pharmacist.
Frequently Asked Questions
Why does everything taste metallic?
Clarithromycin commonly causes a metallic or bitter taste. This is temporary and will disappear when you finish the course.
Can I take Clarithromycin if I'm allergic to penicillin?
Yes, Clarithromycin is a macrolide antibiotic, not a penicillin, so it's often prescribed for people with penicillin allergies.
Why are there so many drug interactions?
Clarithromycin affects liver enzymes that break down many other medications, potentially increasing their levels and effects.
Is it safe to take with my heart medication?
This depends on the specific heart medication. Always inform your GP about all medications you're taking before starting Clarithromycin.
Medically Reviewed by: Mohammed Hassan - Independent Prescriber
Last Updated: 2025-01-14