Biaxin XL

Biaxin XL is an antibiotic and treats infection. Finish taking all of your medication as directed. Even if you feel better, do not stop taking medication unless your doctor tells you to stop.

Biaxin XL Overview

Reviewed: December 15, 2014

Biaxin XL is an antibiotic medication commonly prescribed to treat strep throat, sinus infections, bronchitis, pneumonia, skin infections, ear infections, as well as other bacterial infections. Biaxin XL belongs to a group of drugs called macrolide antibiotics which work by inhibiting protein synthesis, stopping bacterial growth and reproduction.

This medication comes in an extended-release tablet. Biaxin XL is usually taken once daily, with food.

Common side effects of Biaxin XL include nausea and diarrhea.

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  • Other
  • Bacterial Infections
  • Bronchitis
  • Chlamydia Infections
  • Duodenal Ulcer
  • Endocarditis, Bacterial
  • Haemophilus Infections
  • Helicobacter Infections
  • Mycobacterium Infections, Nontuberculous
  • Otitis Media
  • Pneumonia, Mycoplasma
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  • Skin Diseases, Infectious
  • Staphylococcal Infections
  • Streptococcal Infections
  • Tonsillitis

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Uses of Biaxin XL

Clarithromycin is a prescription antibiotic medication used to treat the following:


  • strep throat
  • tonsillitis
  • sinus infections
  • bronchitis
  • pneumonia
  • skin infections
  • Mycobacterial infections due to Mycobacterium avium, or Mycobacterium intracellulare
  • Helicobacter pylori (H. pylori) infection in people with duodenal ulcers (intestinal ulcers), when used in combination with other medications 


  • strep throat
  • tonsillitis
  • sinus infections
  • pneumonia
  • ear infections
  • Mycobacterial infections due to Mycobacterium avium, or Mycobacterium intracellulare
Clarithromycin extended-release tablets are approved to treat the following infections in adults:
  • Sinus infections
  • Bronchitis
  • Pneumonia

This medication may be prescribed for other uses. Ask your doctor or pharmacist for more information.


Biaxin XL Drug Class

Biaxin XL is part of the drug class:

Side Effects of Biaxin XL

Some clarithromycin side effects can be serious. See "Drug Precautions" section.

Most side effects are mild. During clinical trials, the most frequently reported side effects of clarithromycin in adults included:

  • diarrhea
  • nausea
  • abnormal taste
  • indigestion
  • stomach pain or discomfort
  • headache (2%)

In children, the most frequently reported side effects were:

  • diarrhea
  • vomiting 
  • stomach pain 
  • rash
  • headache 

This is not a complete list of clarithromycin side effects. Ask your doctor or pharmacist for more information.

Biaxin XL Precautions

Serious side effects can occur with clarithromycin use. While these side effects do not commonly occur, they are potentially dangerous and should be reported immediately to your healthcare provider.

Clarithromycin may cause a serious condition known as QT prolongation, causing a change in the heart rhythm. The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may affect the heart rhythm. Before receiving clarithromycin, tell your doctor or pharmacist if you have heart problems such as QT prolongation, heart failure, or slow heartbeat.

Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use diuretics ("water pills"). Severe sweating, diarrhea, or vomiting can also increase your risk of QT prolongation. 

Clarithromycin should be avoided for people receiving certain heart medications. Talk to your doctor if you receive medications for irregular heart rate, or if you have any other heart condition.

Clarithromycin, like other antibiotics, can cause Clostridium difficile associated diarrhea. When certain bacteria grow too rapidly in the colon, this serious condition can occur. Tell your doctor if you experience bloody, watery diarrhea.

This medication can cause allergic reactions, which may be severe. Signs of allergic reaction include:

  • rash
  • hives
  • itching
  • swelling
  • difficulty breathing

Biaxin XL Usage

Take clarithromycin exactly as directed. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand.

Clarithromycin comes as a tablet, an extended-release (long-acting) tablet, and a suspension (liquid) to take by mouth.

  • The regular tablet and liquid are usually taken with or without food twice daily (every 12 hours), with a full glass of water.
  • The extended-release tablet is usually taken with food once daily, swallowed whole. Do not chew, crush or split them.
  • Take clarithromycin at around the same time(s) every day.
  • Clarithromycin is usually taken for 7 to 14 days. Your doctor may tell you to take clarithromycin for a longer time depending on your condition.  
  • Do not take more or less of it or take it more often than prescribed by your doctor.
  • Shake the suspension well before each use to mix the medication evenly.

After the first few days of treatment, you should begin to feel better. Take clarithromycin until you finish the prescription, even if you feel better. If you stop taking clarithromycin too soon, or skip doses, your infection may not be completely treated and the bacteria may become resistant to antibiotics.