Clarithromycin — what it treats and how to use it safely

Clarithromycin is a common macrolide antibiotic used for chest infections, sinusitis, some skin infections, and to help treat H. pylori in ulcers. It kills or stops bacteria from growing, but it won't help viral colds or the flu. Use it only when a doctor prescribes it and follow their instructions closely.

How clarithromycin is used and dosed

Typical adult doses are 250–500 mg taken twice a day. For certain infections your doctor may prescribe a higher or longer course. There’s also an extended-release 500 mg form that’s taken once daily for some conditions. For H. pylori, clarithromycin is often combined with other drugs (like a proton pump inhibitor and another antibiotic). Children get doses adjusted by weight — never guess a child’s dose.

Always check with your prescriber before changing dose or stopping early. Stopping antibiotics too soon can let bacteria survive and become resistant, making future infections harder to treat.

Side effects, interactions, and smart tips

Common side effects are stomach upset, nausea, vomiting, diarrhea, and an unusual metallic or bitter taste. Headache and mild liver enzyme increases can happen. Rare but serious problems include severe allergic reactions, liver inflammation (watch for yellow skin or dark urine), and heart rhythm changes in people with certain heart conditions.

Clarithromycin interacts with several medicines. It can raise levels of some statins (like simvastatin), certain blood thinners (warfarin), some anti-arrhythmics, and drugs broken down by the CYP3A4 enzyme. Combining clarithromycin with colchicine or some anti-fungal drugs can be dangerous if you have kidney or liver issues. Always tell your doctor or pharmacist every medicine and supplement you take, including over-the-counter drugs.

Simple tips to make treatment safer: take your dose with food if your stomach bothers you; finish the entire course even if you feel better; avoid mixing it with grapefruit juice (it can affect drug levels); and follow lab checks if your doctor orders liver or heart monitoring.

Watch for warning signs that need immediate care: a rash with swelling or trouble breathing, signs of severe liver trouble (jaundice), severe diarrhea or blood in stool, fainting, or a fast/irregular heartbeat. Call your provider or go to ER if any of these occur.

Storage and extra advice: store clarithromycin at room temperature away from moisture and heat. If you miss a dose, take it when you remember unless it’s almost time for the next one — don’t double up. Don’t share your pills.

Antibiotic resistance is real. Don’t ask for clarithromycin for a viral illness and avoid using leftover antibiotics. If infections come back after treatment, tell your doctor — they may need to test for resistant bacteria or choose a different medicine.

Questions about your specific situation? Your prescriber or pharmacist can explain how clarithromycin fits your health needs and any special precautions you should take.