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Azithromycin

Brand names: Zithromax, Z-Pak

Azithromycin is an antibiotic for many bacterial infections, such as some pneumonias, chlamydia, and ear and sinus infections.

Brand namesZithromax, Z-Pak
Type of medicineMacrolide antibiotic
Prescription?Prescription
ImportantThis page is general information, not a prescription. Don't start, stop, or change a medicine without talking to your provider or pharmacist.

Overview

It's often given as a short course because it stays in the body for days.

It doesn't work on colds, flu, or other viruses.

What it's used for

  • Some pneumonias and bronchitis
  • Chlamydia
  • Sinus, ear, and throat infections (in people allergic to penicillin)
  • Skin infections
  • Traveler's diarrhea

How to take it

  • Tablets can be taken with or without food.
  • Finish the full course even if you feel better.
  • Take antacids with aluminum or magnesium at a different time.

Your dose depends on your health and other medicines. Always follow your prescription label, and ask your pharmacist if anything is unclear.

Side effects

Common side effects

  • Diarrhea
  • Nausea
  • Stomach pain
  • Vomiting
Call 911Fainting or a fast, irregular heartbeat
Call 911Swelling of the face, lips, or throat, hives, or trouble breathing
Call 911A blistering, peeling, or widespread red rash, especially with fever
Call your provider todaySevere watery or bloody diarrhea, even weeks after finishing (possible C. diff infection)
Call your provider todayYellow skin or eyes or dark urine

Warnings

  • It can affect heart rhythm, especially in people with heart rhythm problems or low potassium.
  • Tell your provider about liver problems or myasthenia gravis.

Other medicines, foods, and alcohol

  • Other medicines that affect heart rhythm add to the risk.
  • It can raise levels of warfarin and digoxin.

Tell your provider and pharmacist about every medicine, vitamin, and supplement you take.

Pregnancy and breastfeeding

Commonly used in pregnancy when needed.

Missed doses, overdose, and storage

If you miss a dose

Take it as soon as you remember. If it's almost time for the next dose, skip the missed one. Don't double up, and still finish the full course.

If someone takes too much

Call Poison Control at 1-800-222-1222 or get help online at poison.org. Call 911 if the person collapses, has a seizure, has trouble breathing, or can't be woken.

Storing it

Store at room temperature, away from heat and moisture (not in the bathroom), and out of reach of children and pets.

Conditions it's used for

Sources

Last updated 2026-11-13.