All You Need to Know About Clarithromycin

By Terez Malka, MD
Medically reviewed checkmarkMedically reviewed
January 12, 2022

When you have a bacterial infection such as pneumonia, or a bacterial infection of the ears, sinuses, skin, or throat, your healthcare provider may prescribe a medication called clarithromycin.

Clarithromycin is a macrolide antibiotic that is used to kill certain bacteria that cause infections.

Macrolides are a popular antibiotic option for people who are allergic to penicillin.

In this article, I’ll tell you more about what clarithromycin is and conditions it’s used to treat.

I’ll talk about how to take it, and list some side effects patients experience when taking clarithromycin.

I’ll also give some warnings and precautions for taking this medication, including other drugs that it can interact with.

Finally, I’ll tell you when to see a doctor or other healthcare provider.

What is Clarithromycin?

Clarithromycin (Biaxin, Biaxin XL) is a macrolide antibiotic.

This class of drugs are often prescribed for the treatment of bacterial infections in people who are allergic to penicillin.

Clarithromycin works by stopping bacteria from making certain proteins, which makes the bacteria unable to multiply.

Only use clarithromycin when prescribed by a healthcare professional.

It will not work for colds, flu, or other viral infections. 

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Uses for Clarithromycin

Clarithromycin is prescribed to treat certain bacterial infections, including:

Clarithromycin can also be used to treat and prevent a type of lung infection that often affects people living with human immunodeficiency virus (HIV) called disseminated Mycobacterium avium complex (MAC).

It can also sometimes be used to prevent heart infection in patients having dental or other procedures.

When used in combination with lansoprazole and amoxicillin, clarithromycin can also be used to treat Helicobacter pylori (H. pylori), a bacterium that causes stomach ulcers.

How to Take Clarithromycin

Follow the directions on the prescription label carefully.

If any of the directions are unclear, ask your provider about how to proceed.

Clarithromycin comes in tablet, extended-release tablet, and liquid (suspension) forms.

The tablet and liquid medicine are generally taken with or without food three times a day for 7-14 days. If your provider recommends otherwise, follow their instructions.

Whenever possible, take the medicine at about the same time each day.

If you are prescribed the extended-release tablet, you’ll likely be advised to take the medicine with food once a day for 7-14 days. 

When taking clarithromycin:

  1. Follow the instructions on the prescription label carefully.
  2. Ask your provider or pharmacist about any instructions or precautions you don’t understand.
  3. Do not take more or less of the medication than prescribed by your provider.
  4. If using the liquid form, shake well before each use to mix the medication evenly.
  5. If using extended-release tablets, swallow each tablet whole. Do not split, chew, or crush the medicine.
  6. Don’t skip doses or stop taking the medication before the prescription is complete.
  7. Don’t stop taking the medication, even if you start to feel better.

Your symptoms should start to improve within the first few days of treatment.

If your symptoms do not improve after one week of starting your prescription, reach out to your provider for more information.

If you forget to take a dose, take the missed dose as soon as you remember it, unless you are close to the timing of the next dose.

In that case, skip the missed dose and continue the regular dosing schedule.

Never take an extra or double dose to make up for a missed one.

Taking more of the medication than prescribed is not recommended and should be avoided.

If you’ve accidentally taken too much of the medication, reach out to your provider as soon as possible. 

Side Effects of Clarithromycin

The most common adverse side effects reported in patients taking clarithromycin are:

If any of these symptoms become severe or don’t go away, reach out to your healthcare provider as soon as possible.

Risks and Warnings for Clarithromycin

Before taking clarithromycin, tell your provider about your complete medical and medication history, including any chronic health conditions you may have, such as heart disease, kidney disease, or other allergies.

A review conducted by the Food and Drug Administration (FDA) found that there may be long-term risks with clarithromycin (Biaxin) use in patients with heart disease.

The report found a potential for increased risk of heart problems or death in patients with heart disease.

These risks can occur years after taking the medication. 

If you have heart disease and have been prescribed clarithromycin, talk to your provider about  alternative antibiotics. 

Allergic reaction

Data shows that an allergic reaction to antibiotics occurs in approximately one in 15 people, causing symptoms ranging from skin rashes and itching to difficulty breathing.

Tell your prescriber if you’re allergic to clarithromycin, erythromycin, telithromycin, or any other medications or antibiotics before starting this medicine.


To avoid a possible clarithromycin overdose, take the medicine exactly as directed by your pharmacist or provider. 

Symptoms of a clarithromycin overdose may include:

  • Stomach pain
  • Nausea
  • Vomiting
  • Diarrhea

If you experience any signs of a clarithromycin overdose, call poison control at 1-800-222-1222 or reach out to your healthcare provider immediately.

If you suspect a loved one or friend is unresponsive due to a clarithromycin overdose, call 9-1-1.

Pregnancy or lactating

Clarithromycin is generally considered safe in pregnancy and while breastfeeding.

Before starting clarithromycin, tell your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. 

Drug Interactions with Clarithromycin

Examples of medicines that may interact with clarithromycin include:

  • Anticoagulants (blood thinners)
  • Benzodiazepines, including alprazolam (Xanax), midazolam, and triazolam (Halcion)
  • Calcium channel blockers
  • Certain medications for HIV, including atazanavir (Reytaz), didanosine (Videx), efavirenz (Sustiva), and saquinavir (Invirase)
  • Certain medications for irregular heartbeat such as amiodarone (Pacerone) and disopyramide (Norpace)
  • Some oral medications for diabetes
  • Statins (cholesterol lowering medications)
  • Some medications used to treat erectile dysfunction (ED), including sildenafil (Viagra) and tadalafil (Cialis)

Other medications can also interact with clarithromycin.

Tell your provider about all medications, vitamins, supplements, or herbal products you’re currently taking.

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When to See a Doctor

Serious side effects are rare, but possible, when taking clarithromycin.

If you experience any of the following side effects, reach out to your provider for medical advice as soon as possible:

  • Chest pain
  • Shortness of breath or difficulty breathing
  • Pain or weakness in your side body
  • Slurred speech
  • Rash
  • Hives
  • Fever
  • Muscle weakness (including difficulty talking, chewing, or performing daily activities)
  • Swelling of the face, throat, tongue, lips, hands, feet, ankles, lower legs, or eyes
  • Hoarseness
  • Peeling or blistering skin
  • Yellowing of the skin or eyes
  • Unusual bleeding or bruising
  • Loss of appetite
  • Dark-colored urine
  • Double vision
  • Fast, pounding, or irregular heartbeat
  • Flu-like symptoms
  • Any sign that your original infection has returned

How K Health Can Help

Did you know you can get affordable primary care with the K Health app? Download K Health to check your symptoms, explore conditions and treatments, and if needed text with a provider in minutes. K Health’s AI-powered app is based on 20 years of clinical data.

Frequently Asked Questions

How should antibiotics be stored for use?
Proper storage depends on the type of antibiotic you’re using. In general, it’s a good idea to keep antibiotic tablets away from light, excess heat, and moisture. When taking clarithromycin tablets, store the tablets at room temperature. When taking clarithromycin in liquid form (also called suspension), do not refrigerate the liquid. Store all antibiotics in a safe location, tightly closed, and away from children.
Are there any alternatives to clarithromycin?
There are several possible alternatives to clarithromycin, including amoxicillin and others. If you’re interested in an alternative, talk to your healthcare provider for more information.
Is clarithromycin a penicillin-based antibiotic?
No. Clarithromycin belongs to a class of antibiotics called macrolides, a common alternative for people who are allergic to penicillin.

K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Terez Malka, MD

Dr. Terez Malka is a board-certified pediatrician and emergency medicine physician.

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