What is Azithromycin used for?

Azithromycin is an antibiotic that is commonly used for the following infections caused by certain bacteria.

  • Lung infections (e.g., bronchitis, pneumonia)
  • Throat infections (e.g., pharyngitis, tonsillitis)
  • Sinus infections
  • Skin infections
  • Ear infections in children
  • Certain sexually transmitted infections
  • Infection that affects female reproductive organs called pelvic inflammatory disease (PID)
  • Certain infections in people with HIV/AIDS

Azithromycin may not be appropriate for some of the infections listed above, depending on which germs are causing the infection. Bacteria in some locations may have developed resistance to azithromycin , which will make it less effective.

Azithromycin may also be used for other conditions as determined by your healthcare provider.

How does azithromycin work?

Azithromycin stops certain types of bacteria from making proteins they need to grow and multiply.

How is Azithromycin supplied (dosage forms)?

Azithromycin is available as Zithromax, Zithromax Z-PAK, and generic azithromycin supplied in the following dosage forms that are taken by mouth.

  • 250 mg oral tablets
  • 500 mg oral tablets
  • 600 mg oral tablets
  • 100 mg oral suspension
  • 200 mg oral suspension
  • 1 g oral suspension
  • 2 g extended-release oral suspension

Azithromycin is also available in injectable forms.

How should I store azithromycin?

Oral Tablets. Most azithromycin oral tablets should be stored at room temperature, between 68 F to 77 F (20 C to 25 C). It can be exposed to temperatures between 59 F to 86 F (15 C to 30 C), for shorter periods of time, such as when transporting it. Store in a cool, dry place, in a tightly closed container.

Oral Liquid. Azithromycin oral liquid should be stored at room temperature or in the refrigerator between 41 F to 86 F (5 C to 30 C) and used within 10 days. You should not freeze it. Safely throw away any unused portion after the full treatment is finished.

Side Effects

What are the most common side effects of azithromycin?

The most common side effects of azithromycin are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

  • Nausea and vomiting
  • Diarrhea
  • Stomach pain

There may be other side effects of azithromycin that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at or by calling 866-234-2345.

What are the serious side effects of azithromycin?

While less common, the most serious side effects of azithromycin are described below, along with what to do if they happen.

Severe Allergic Reactions. Azithromycin can cause allergic reactions, which can be serious. Stop using Azithromycin and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching, skin rash, or pale red bumps on the skin called hives
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Angioedema. Azithromycin may cause a certain type of allergic reaction called angioedema. The usual symptoms of this reaction include swelling of the lips, face, tongue, or throat. Stop using the medicine and call your healthcare provider if you have this type of swelling. If it is causing problems breathing, seek immediate medical attention.

Liver Damage. Liver damage, also called hepatotoxicity, can happen when taking azithromycin. Call your healthcare provider right away if you have any of the following symptoms of liver damage.

  • Nausea or vomiting
  • Stomach or belly pain
  • Fever
  • Weakness or unusual tiredness
  • Itching
  • Loss of appetite
  • Light colored poop
  • Dark colored urine
  • Your skin or the whites of your eyes turning yellowish in color (also called jaundice)

Heart Rhythm Changes. Azithromycin may cause rare dangerous heart rhythm problems called QT prolongation and torsade de pointes. Some people have a higher risk of this, including people who are older, have other people in their family who have had these conditions, have low potassium or magnesium, or who take some medicines for other heart rhythm problems. Tell your healthcare provider right away if you faint or have changes in your heart rate or rhythm, such as fast or skipping heartbeat.

Antibiotic-associated Diarrhea. An overgrowth of germs Clostridioides difficile, or "C. diff," can happen in your gut with many types of antibiotics, including azithromycin. This can cause a condition known as antibiotic-associated diarrhea and can happen even up to 2 months after stopping the antibiotic. Call your healthcare provider right away if you have any of the following symptoms of this condition.

  • Watery diarrhea
  • Diarrhea that does not go away
  • Blood in your poop
  • Severe stomach cramps
  • Fever that starts after you start or finish the medicine

Infantile Hypertrophic Pyloric Stenosis. A condition called infantile hypertrophic pyloric stenosis can happen in babies who are less than 6 weeks old after being given azithromycin. This condition makes it harder for food to move from the baby’s stomach into their intestines, causing vomiting and trouble keeping food down. Call your healthcare provider right away if your baby throws up or is irritable after feeding. 

Warnings & Precautions

Who should not use azithromycin?

Allergies to Ingredients. People who are allergic to any of the following should not use azithromycin products.

  • Zithromax or Zithromax Z-PAK
  • Zmax
  • Azithromycin
  • Erythromycin
  • Any other medicine known as a macrolide
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific azithromycin products they stock.

Liver Problems. Azithromycin should not be used if your liver is not working as well as it should be. If there is a concern about the health of your liver, your healthcare provider may do tests to determine if it is working well enough to take this medicine.

What should I know about azithromycin before using it?

Do not use azithromycin unless it has been prescribed to you by a healthcare provider. Use it as prescribed.

Do not share azithromycin with other people, even if they have the same condition as you. It may harm them.

Keep azithromycin out of the reach of children. Since the oral liquid may be kept in a refrigerator, take special precautions to keep it away from children who also use the refrigerator.

People who are over 60 years old can be at greater risk for some side effects from azithromycin. Talk to your healthcare provider about your risks if you are in this age group.

What should I tell my healthcare provider before using azithromycin?

Tell your healthcare provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them determine if azithromycin is right for you.

In particular, make sure that you discuss any of the following.

Heart Problems. Tell your healthcare provider if you or anyone in your family has a history of heart attack or an irregular heartbeat (arrhythmia), especially a condition called “QT prolongation” or “long QT syndrome.”

Myasthenia Gravis. Tell your healthcare provider if you have a condition called Myasthenia gravis (MG). Azithromycin can make your symptoms like muscle weakness and breathing problems worse. 

Current and Past Health Conditions. Tell your healthcare provider if you have any of the following health conditions.

Pregnancy. It is not known if or how azithromycin could affect pregnancy or harm an unborn baby. Tell your healthcare provider if you are or plan to become pregnant.

Breastfeeding. Azithromycin passes into breast milk. Tell your healthcare provider if you are breastfeeding or plan to breastfeed. Your healthcare provider will advise you if you should use azithromycin while breastfeeding. Monitor your baby for diarrhea, vomiting, or rash if you are breastfeeding while taking azithromycin.


Does azithromycin interact with foods or drinks?

There are no known interactions between azithromycin and foods or drinks.

It is unknown if drinking alcohol will affect azithromycin.

Does azithromycin interact with other medicines?

Always tell your healthcare provider about any prescription or OTC medicines, vitamins/minerals, herbal products, and other supplements you are using.

In particular, make sure that you discuss if you are using any of the following before using azithromycin.

  • Nelfinavir, which is a medicine used for HIV
  • Warfarin, which is a blood thinner
  • Digoxin, which is a medicine used for heart problems
  • Colchicine, which is a medicine commonly used for gout
  • Phenytoin (Dilantin, Phenytek, and others), which is a medicine to control seizures
  • Antacids that contain aluminum or magnesium

Azithromycin may alter the blood levels of some other medicines. Tell your healthcare provider about all medicines that you take or have recently taken.

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Overdose/Missed Dose

What should I do if I accidentally use too much azithromycin?

If you or someone else has used too much azithromycin, get medical help right away, call 911, or call a Poison Control center at 800-222-1222. 

What should I do if I miss a dose of azithromycin?

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only take the next dose. Do not take double or extra doses.

It is important to complete your prescribed course of azithromycin, even if your symptoms get better or go away. This will reduce the risk that future infections are resistant to azithromycin or other similar medicines.

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