Clarithromycin: Uses, Dosage, Side Effects, and Interactions

If you’ve been prescribed clarithromycin, you probably want to know what it does, how to take it safely, and what to watch out for. In plain English, clarithromycin is a macrolide antibiotic that fights bacterial infections by stopping bacteria from making proteins they need to grow. Doctors commonly use it for lung infections, skin infections, and certain stomach bugs. Below you’ll find the most useful facts you need to start the medication with confidence.

How Clarithromycin Works

Clarithromycin binds to a part of the bacterial ribosome, the cell’s protein‑making machine. By blocking that spot, the drug prevents the bacteria from producing essential proteins, which slows their growth and lets your immune system clear the infection. Because it targets a specific bacterial process, it usually spares human cells, making it a relatively safe choice for many adults.

The drug is absorbed well from the gut, so you can take it as a tablet, an oral suspension, or even an IV in a hospital setting. Food doesn’t drastically lower its effectiveness, but a high‑fat meal can slow absorption a bit, which is why many doctors suggest taking it with a light snack or on an empty stomach for the fastest action.

Clarithromycin also has anti‑inflammatory properties, which is why it sometimes helps with conditions like chronic sinusitis or certain skin disorders where inflammation plays a role. However, its primary job is to kill bacteria, so you should only use it when your doctor says you have a bacterial infection—not a virus.

Practical Tips for Safe Use

Dosage matters. Typical adult doses range from 250 mg to 500 mg every 12 hours, depending on the infection type and severity. Always follow the exact schedule your prescriber gives you. Skipping doses can let bacteria survive and become resistant, which makes future infections harder to treat.

Complete the full course. Even if you feel better after a few days, keep taking the medication until the bottle is empty. Stopping early can let lingering bacteria bounce back, and you might need a stronger antibiotic later.

Watch for side effects. The most common complaints are mild stomach upset, nausea, or a change in taste. A small number of people get diarrhea that can be watery or even bloody—if that happens, call your doctor right away. Another rare but serious side effect is a change in heart rhythm called QT prolongation; you’ll know if you’ve been warned because the doctor will check your heart rhythm if you have a history of heart problems.

Check for drug interactions. Clarithromycin can boost the levels of many other medicines, such as certain cholesterol drugs (statins), blood thinners (warfarin), and some anti‑seizure meds. If you’re on any of these, your doctor may adjust the doses or monitor you more closely. Over‑the‑counter supplements, especially St. John’s wort, can also affect how clarithromycin works.

Alcohol and smoking. A little alcohol isn’t a deal‑breaker, but heavy drinking can irritate your stomach and make side effects worse. Smoking doesn’t directly affect the drug, but it can worsen the infections clarithromycin is meant to treat, like pneumonia, so quitting is a smart move.

Pregnancy and breastfeeding. The drug is generally considered safe in pregnancy, but you should still discuss it with your healthcare provider. It does pass into breast milk in small amounts; most doctors say it’s okay to continue breastfeeding while you’re on clarithromycin, but keep an eye on the baby for any unusual signs.

Finally, store clarithromycin at room temperature, away from moisture and heat. If you have any leftover pills after finishing the course, don’t keep them for future use—talk to your pharmacist about proper disposal.

By sticking to the prescribed schedule, monitoring side effects, and staying aware of interactions, you can make clarithromycin work effectively and safely. If any question pops up while you’re on the medication, your doctor or pharmacist is the best go‑to for reliable answers.