Clarithromycin use — when to take it and how to stay safe

Clarithromycin is a macrolide antibiotic doctors prescribe for ear, sinus, throat, skin, chest infections and certain stomach infections like H. pylori. It works by stopping bacteria from growing rather than instantly killing them, so you usually feel better after a few days but must finish the full course. Below are clear, practical points you can use right now.

Quick dosing & common uses

Typical adult doses are 250–500 mg taken twice daily. Some infections need 7 days, others 10–14 days. For H. pylori treatment, clarithromycin 500 mg twice daily is often combined with a proton-pump inhibitor and amoxicillin or metronidazole for a 7–14 day course. There’s also an extended-release 500 mg tablet taken once daily for some conditions — follow your doctor’s instructions exactly.

If you have kidney problems or are elderly, your prescriber may lower the dose or space it out. Don’t guess on dose changes — check the leaflet or ask your pharmacist if you have reduced kidney function.

Side effects, interactions, and safety tips

Common side effects are nausea, diarrhea, stomach pain, and a metallic or altered taste. Most are mild and go away after stopping the drug. Serious but rarer problems include liver inflammation, severe allergic reactions, and irregular heart rhythm (QT prolongation).

Watch for warning signs: severe diarrhea (especially with blood), yellowing skin or eyes, dark urine, fainting, or fast/irregular heartbeat. If these happen, stop the drug and seek urgent care.

Clarithromycin interacts with many medicines. Common risky combos include:

• Statins like simvastatin or lovastatin — increased risk of muscle damage.
• Warfarin — clarithromycin can raise INR and bleeding risk.
• Colchicine — risk of serious toxicity if combined.
• Some antiarrhythmics, antipsychotics, and other drugs that lengthen the QT interval — may cause dangerous heart rhythm problems.

Always tell your doctor or pharmacist about every medicine you take, including over‑the‑counter drugs and herbal supplements.

Pregnancy and breastfeeding: talk to your doctor. Some studies suggest caution in pregnancy, and clarithromycin passes into breast milk. Your prescriber will weigh risks and benefits and suggest alternatives if needed.

Practical tips: finish the full course even if you feel better; don’t use antibiotics for colds or flu (they’re viral); store tablets at room temperature away from moisture; keep a list of reactions and bring it to appointments.

Buying online: only use a licensed pharmacy that requires a prescription, shows clear contact details, and protects your payment. If a site sells prescription antibiotics without asking for a prescription or offers prices that seem unreal, walk away.

Need a repeat or have ongoing symptoms despite treatment? Ask for a culture or specialist review — persistent infections sometimes need different antibiotics or longer courses. If you treat clarithromycin with care, it’s an effective option for many bacterial infections.