Comparison of Azithromycin and Clarithromycin

If you’ve ever had the unpleasant experience of dealing with an upper respiratory infection, ear infection, or chronic bronchitis, it’s possible that you received treatment with a type of medication called a broad spectrum antibiotic. 

Broad spectrum antibiotics are used to treat common bacterial infections of many different kinds, and they work by killing harmful pathogens in the body or preventing bacteria from reproducing. 

Two of the most common antibiotics are clarithromycin and azithromycin. Other common antibiotics in this class include erythromycin and telithromycin.

If you are curious about the difference between the two drugs, we have put together a comprehensive comparison of azithromycin and clarithromycin.

Overview

Clarithromycin, sold under the brand name Biaxin, and Azithromycin, sold under the brand name Zithromax, are both FDA-approved macrolide antibiotics that are prescribed for the treatment of a wide variety of bacterial infections. 

Macrolide antibiotics work by preventing bacteria from producing certain proteins that are required for reproduction and survival. 

Conditions Treated

Clarithromycin and azithromycin are both used for the full eradication of certain bacterial infections in pediatric and adult applications. 

Azithromycin is most commonly used for the treatment of the following:

• Infections of the middle ear (otitis media)
• Sinusitis
• Skin infections
• Pneumonia
• Laryngitis
• Mycobacterial infections
• Tonsillitis
• Sexually transmitted diseases such as gonorrhea and chlamydia
• Infections caused by Mycobacterium pneumoniae
• Infections caused by Haemophilus influenzae
• Infections caused by Streptococcus pneumoniae
• Infections caused by some strains of Staphylococcus aureus

Clarithromycin is also used to treat a variety of bacterial infections and infectious diseases, including:

• Acute sinusitis
• Bronchitis
• Community-acquired pneumonia
• Uncomplicated skin and skin structure infections
• Mycobacterial infections
• Acute otis media
• Heliobacter pylori infection and duodenal ulcer disease
• Pharyngitis
• Tonsillitis

Clarithromycin and azithromycin can both be used to treat a number of different types of bacterial infections, but one may be more effective than the other for treating certain types of bacterial infections.

Available Forms

Both azithromycin and clarithromycin are available in a number of different forms. 

Which form of the medication you are prescribed will vary depending on the infection that is being treated.

Clarithromycin is available as an oral tablet that comes in an immediate-release and extended-release form, and it is also available as an oral suspension.  

Azithromycin is most commonly prescribed as an oral tablet, powder for oral suspension, injection, and eye drop.

Most people receive azithromycin in the form of a Z-pak, which includes a specific number of tablets that are ingested over a dosing schedule of five days. 

Standard Dosage and Length of Treatment

Bacterial infections must be treated over the course of several days, but patients typically start to feel better before their prescription is finished. 

When patients stop taking their antibiotic before finishing the full course of the prescription, they allow the remaining bacteria in their bodies to adapt to the antibiotic, which can lead to antibiotic resistance. 

Because clarithromycin and azithromycin are typically prescribed for a treatment length of several days, it is critical that patients take their prescribed dose every day until their prescription is gone in order to prevent antibiotic resistance.

Azithromycin is most commonly prescribed in the form of a Z-pak. When using a Z-pak, patients take two tablets on the first day of treatment and one tablet each day for the next four days.

If a patient is prescribed azithromycin outside of a Z-pak, the length of treatment varies depending on the condition being treated.

The typical adult dose of azithromycin is between 500 and 2000 mg, which is taken in single doses over the course of multiple days.

Clarithromycin is prescribed in strengths of 250 mg to 500 mg in its immediate-release form and 500 mg in its extended release form.

Clarithromycin is typically taken one to two times per day for infections in adult patients; the typical course of treatment lasts anywhere from 7 to 10 days, or longer.

Side Effects

As medications in the same drug class, azithromycin and clarithromycin are known to cause similar side effects.

However, there are some significant differences in the side effects and adverse events caused by each medication as well. Common side effects associated with azithromycin include:

• Abdominal pain
• Vomiting
• Nausea
• Diarrhea or loose stools

Atypical side effects of azithromycin include:

• Vaginitis
• Ringing in the ears
• Tongue discoloration
• Indigestion or gastrointestinal problems
• Rash
• Muscle weakness

Rare but serious side effects of azithromycin include:

• Cholestatic jaundice
• Serious allergic reactions
• Angioedema
• Abnormal heartbeat
• Abnormal liver tests
• Steven-Johnson Syndrome

Common side effects of clarithromycin include:  

• Stomach pain
• Diarrhea
• Vomiting
• Abnormal taste in the mouth
• Nausea

Less common side effects of clarithromycin include:

• Hearing loss
• Muscle weakness
• Slurred speech
• Severe abdominal pain
• Persistent nausea

Rare but serious side effects associated with clarithromycin include:

• Fast or irregular heartbeats
• Liver problems
• Allergic or hypersensitivity reactions

This may not be a complete list of side effects. If side effects persist or worsen, consult your healthcare provider. 

Clarithromycin and azithromycin, like other antibiotics, are associated with the risk of a dangerous condition called Clostridium difficile-associated diarrhea. 

Clostridium difficile is a type of bacteria that can cause inflammation in the colon (pseudomembranous colitis) that can cause symptoms ranging from mild diarrhea to severe inflammation. Left untreated, the condition can be severe. 

Therefore, patients who begin to exhibit signs of pseudomembranous colitis, including diarrhea, abdominal pain, fever, and shock, after beginning treatment with either medication should contact a healthcare professional immediately. 

Drug Interactions

Clarithromycin may interact with a number of drugs, including the following:

• Colchicine
• Some statins (drugs used to treat cholesterol) including simvastatin and lovastatin
• Sildenafil, tadalafil, and vardenafil
• Ergotamine and dihydroergotamine
• Pimozide
• Drugs used for the treatment of HIV
• Antifungal drugs such as ketoconazole

Azithromycin commonly reacts with many of the same medications as clarithromycin:

• Aluminum or magnesium-based antacids, including Maalox and Mylanta, which affect the body’s ability to absorb azithromycin. 
• Amiodarone
• Pimozide
• Hydroxychloroquine
• Quinidine
• Dofetilide

Consult a healthcare provider for other possible drug interactions.

Warnings

Azithromycin should not be used to treat pneumonia in patients who have any of the following medical conditions:

• Nosocomial (hospital-acquired) infections
• Known or suspected bacteremia (bacteria in the blood)
• Cystic fibrosis
• Individuals who are elderly or disabled, are currently hospitalized, do not have a spleen, or have a compromised immune system should not be treated with azithromycin. 
• People with any of the following medical conditions should use caution when taking clarithromycin:
• Medical history of liver disease or liver problems
• Heart problems, including irregular heartbeat and coronary artery disease

Cost

Azithromycin and clarithromycin are both available in both name brand and generic forms, but they are usually sold as generic drugs.

Both azithromycin and clarithromycin are covered by nearly all types of commercial health insurance plans, as well as Medicare and Medicaid. 

People without insurance can purchase both drugs for less than 20 dollars even without insurance.

Regardless of your insured status, using a pharmacy discount card to purchase your prescription can help you save on your medication. 

Summary

Clarithromycin and azithromycin are both broad spectrum antibiotics that can be used for the treatment of many different bacterial infections. 

Both medications belong to a class of drugs called macrolide antibiotics and work in a similar way to treat bacterial infections.  

Both clarithromycin and azithromycin are widely available in their generic forms and are covered by the vast majority of commercial and public health insurance plans. 

It’s possible to make your prescription even more affordable by using a pharmacy discount card from Pharmacists.org regardless of your insured status.

References, Studies and Sources.

https://pubmed.ncbi.nlm.nih.gov/1320067/ 
https://pubmed.ncbi.nlm.nih.gov/8396085/ 
https://www.aafp.org/afp/2004/0115/p420.html 
https://www.rxlist.com/zithromax_vs_biaxin/drugs-condition.htm 
https://www.drugs.com/compare/azithromycin-vs-clarithromycin 
https://www.healthline.com/health/clarithromycin-oral-tablet