Macrolide antibiotic

Zithromax (azithromycin)

Also marketed as Z-Pak. An approved treatment for Bartonellosis and Babesiosis.

FDA Approved (1991)
Preclinical
Phase 1
Phase 2
Phase 3
Approved
1991
Drug facts

The same compound appears under different names depending on the context. Here is how to identify Azithromycin wherever you encounter it, plus the key facts at a glance.

Generic name
Azithromycin
Brand names
Zithromax, Z-Pak
Drug class
Macrolide antibiotic
How it's taken
For bartonellosis, azithromycin is typically given 500 mg on day 1 followed by 250 mg daily for 4 days, though LLMD protocols for chronic bartonellosis may extend treatment to weeks or months.

A macrolide antibiotic used as first-line treatment for Bartonella infections and as part of the standard combination therapy (with atovaquone) for babesiosis.

How Azithromycin works

Azithromycin binds to the 50S ribosomal subunit of bacteria and parasites, blocking the translocation step of protein synthesis. It concentrates inside immune cells (macrophages and neutrophils) at levels 10 to 100 times higher than in surrounding tissue, which is particularly useful against intracellular pathogens like Bartonella henselae.

Mechanism: Macrolide antibiotic that inhibits protein synthesis by binding the 50S ribosomal subunit

Side effects and safety

What patients report

Generally well tolerated. Common side effects include nausea, diarrhea, abdominal pain, and vomiting. Rare but serious risks include severe allergic reactions and severe skin reactions (such as Stevens-Johnson syndrome and DRESS), which have caused deaths, QT prolongation (abnormal heart rhythm), liver damage that can be severe or fatal, Clostridioides difficile-associated diarrhea, and worsening of myasthenia gravis. Some studies found a higher short-term risk of death from heart problems in adults taking azithromycin than with some other antibiotics. The label also warns about a stomach blockage (pyloric stenosis) in newborns given azithromycin and about bacteria becoming resistant to it. Hearing changes have been reported at high doses.

This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.

Taking Azithromycin

For bartonellosis, azithromycin is typically given 500 mg on day 1 followed by 250 mg daily for 4 days, though LLMD protocols for chronic bartonellosis may extend treatment to weeks or months. For babesiosis, azithromycin is paired with atovaquone for at least 7 to 10 days. The usual adult dose is 500 mg on day 1, then 250 mg daily. Higher doses (1000 mg, then 500 mg daily) have been used in people with weakened immune systems or severe disease.

Availability and cost

Generic available

Generic versions may be available at a lower cost. Ask your pharmacist.

Help paying for Zithromax

Pick your insurance to see which help fits. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE; charity funds are the usual route there.

Your insurance
From the drugmaker
Zithromax (Azithromycin)

No drugmaker assistance program for this medicine is published on the maker's official pages.

Good to know: Azithromycin is an older antibiotic sold as a low-cost generic by many manufacturers. There is no single manufacturer assistance program for it. Pharmacy discount programs or a pharmacist can help with cost.

Checked on the drugmaker's official pages on September 24, 2026. Programs change; confirm with the program before you rely on it.

More ways to get help paying for treatment →

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Common questions about Azithromycin

▸What is Azithromycin (Zithromax)?

A macrolide antibiotic used as first-line treatment for Bartonella infections and as part of the standard combination therapy (with atovaquone) for babesiosis.

▸How does Azithromycin work?

Azithromycin binds to the 50S ribosomal subunit of bacteria and parasites, blocking the translocation step of protein synthesis. It concentrates inside immune cells (macrophages and neutrophils) at levels 10 to 100 times higher than in surrounding tissue, which is particularly useful against intracellular pathogens like Bartonella henselae.

▸What are the side effects of Azithromycin?

Generally well tolerated. Common side effects include nausea, diarrhea, abdominal pain, and vomiting. Rare but serious risks include severe allergic reactions and severe skin reactions (such as Stevens-Johnson syndrome and DRESS), which have caused deaths, QT prolongation (abnormal heart rhythm), liver damage that can be severe or fatal, Clostridioides difficile-associated diarrhea, and worsening of myasthenia gravis. Some studies found a higher short-term risk of death from heart problems in adults taking azithromycin than with some other antibiotics. The label also warns about a stomach blockage (pyloric stenosis) in newborns given azithromycin and about bacteria becoming resistant to it. Hearing changes have been reported at high doses.

▸How is Azithromycin taken?

For bartonellosis, azithromycin is typically given 500 mg on day 1 followed by 250 mg daily for 4 days, though LLMD protocols for chronic bartonellosis may extend treatment to weeks or months. For babesiosis, azithromycin is paired with atovaquone for at least 7 to 10 days. The usual adult dose is 500 mg on day 1, then 250 mg daily. Higher doses (1000 mg, then 500 mg daily) have been used in people with weakened immune systems or severe disease.

▸Is Azithromycin FDA approved?

Yes, Azithromycin (Zithromax) is FDA approved (1991) for the treatment of Bartonellosis and Babesiosis.

This page is for informational purposes only and does not constitute medical advice. Drug information is sourced from public databases and peer-reviewed literature and may not reflect the most recent updates. Always discuss treatment options with your healthcare provider. Last reviewed: September 2026.

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