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“Clarithromycin exerts its antibacterial action by binding to the 50S ribosomal subunits of susceptible organisms and inhibiting protein synthesis.”
The elimination half-life of clarithromycin was about three to four hours with 250 mg administered every 12 hours but increased to five to seven hours with 500 mg administered every 12 hours. With a dosing of 250 mg every 12 hours, the principal metabolite, 14-OH clarithromycin, attains a peak steady-state concentration of about 0.6 microgram/mL and has an elimination half-life of five to six hours.↗TGA PIT1✓
A plain-language summary of the cited sources below. Informational only — not medical advice.
Clarithromycin: What Families Need to Know
What is clarithromycin?
Clarithromycin is an antibiotic that belongs to a group of medicines called macrolides. It's a prescription-only medicine (Schedule 4) used to treat certain bacterial infections in adults and children over 12 years old (and in younger children for specific infections).
What is it used for?
Clarithromycin can treat a range of infections caused by bacteria, including:
- Throat infections (strep throat and tonsillitis) - Chest infections like pneumonia and bronchitis flare-ups - Skin infections - Ear infections in children - Whooping cough (pertussis) - Certain infections in people with weakened immune systems, such as those with HIV/AIDS - Stomach ulcers caused by *Helicobacter pylori* (used in combination with other medicines)
How does it work?
Clarithromycin works by stopping bacteria from making the proteins they need to grow and multiply. This gives your body's immune system a chance to fight off the infection.
How is it taken?
- Clarithromycin is usually taken by mouth (as a tablet or liquid) - The dose and duration depend on the type and severity of the infection - Always complete the full course as prescribed, even if your child starts feeling better—stopping early can allow bacteria to survive and become harder to treat
Important safety information
Before starting clarithromycin, tell your doctor if your child:
- Is allergic to clarithromycin or other macrolide antibiotics (like erythromycin or azithromycin) - Has heart rhythm problems or a family history of irregular heartbeat (QT prolongation) - Has low potassium or magnesium levels in their blood - Has liver or kidney problems - Is taking any other medicines—this is very important because clarithromycin can interact with many drugs
Medicines that should NOT be taken with clarithromycin
Clarithromycin can cause dangerous heart rhythm problems if taken with certain other medicines. Your child should not take clarithromycin with:
Curated subset. The full adverse-effect list is in the TGA Product Information; click any citation above to open it.
“Studies demonstrate that clarithromycin undergoes cytochrome P450 dependent N-demethylation and 14-(R)-hydroxylation in the presence of human liver microsomes. Available data indicate that N- demethylation and 14-(R)-hydroxylation of clarithromycin are mediated principally by members of the CYP3A subfamily, most likely CYP3A4, and that CYP2C19, CYP2D6, CYP2E1, CYP1A2, CYP2C9 and CYP2A6 play relatively minor roles.”
- Certain antihistamines (astemizole, terfenadine) - Certain stomach medicines (cisapride, domperidone) - Pimozide (a medicine for mental health conditions) - Ergot medicines (for migraines) - Ivabradine (for heart conditions) - Oral midazolam (a sedative) - Lomitapide (for cholesterol) - Certain statins (lovastatin, simvastatin)—risk of serious muscle problems - Colchicine (for gout)
Always tell your pharmacist and doctor about ALL medicines your child is taking, including over-the-counter medicines, vitamins, and herbal supplements.
Common side effects
These are usually mild and may include:
- Nausea or vomiting - Diarrhoea or constipation - Stomach pain - Headache - Dizziness - Changes in liver blood tests (your doctor may monitor this)
Serious side effects—when to get help
Seek medical attention immediately if your child experiences:
- Signs of liver problems: yellowing of the skin or eyes (jaundice), dark urine, severe tiredness, loss of appetite - Severe or persistent diarrhoea (could be a sign of a serious bowel infection called pseudomembranous colitis) - Fast, irregular, or pounding heartbeat, fainting, or seizures - Severe allergic reaction: swelling of the face, lips, tongue, or throat; difficulty breathing; severe rash - Unusual muscle pain or weakness (especially if taking a statin)
Special considerations
- Pregnancy and breastfeeding: Tell your doctor if your