Azithromycin (Zithromax)

Azithromycin is a medicine used to treat many types of bacterial infections.

It’s commonly prescribed for infections of the lungs, throat, sinuses, ears, skin, urinary tract, cervix, or genitals.

This medicine is in a class of drugs called macrolide antibiotics. It works by stopping the growth of bacteria.

Azithromycin will only help infections caused by certain bacteria and will not work for the common cold, flu, or other viral infections.

The U.S. Food and Drug Administration (FDA) approved this medicine in 1991.

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What is Azithromycin (Zithromax) used for?

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What is the most important information I should know about Azithromycin (Zithromax)?

You should not use azithromycin if you are allergic to it, or if you have ever had:

  • jaundice or liver problems caused by taking azithromycin; or
  • a severe allergic reaction to similar drugs such as clarithromycin, erythromycin, or telithromycin.

Azithromycin oral should not be used to treat pneumonia in people who have:

  • cystic fibrosis;
  • an infection after being in a hospital;
  • an infection in the blood;
  • a weak immune system (caused by diseases such as HIV/AIDS or cancer); or
  • in older adults and those who are ill or debilitated.

Tell your doctor if you have ever had:

  • pneumonia;
  • liver or kidney disease;
  • myasthenia gravis;
  • low levels of potassium in your blood;
  • a heart rhythm disorder; or
  • long QT syndrome (in you or a family member).

It is not known whether this medicine is effective in treating genital ulcers in women.

Tell your doctor if you are pregnant or breastfeeding. Taking azithromycin while breastfeeding may cause diarrhea, vomiting, or rash in the nursing baby.

Azithromycin is not approved for use by anyone younger than 6 months old. Azithromycin should not be used to treat a throat or tonsil infection in a child younger than 2 years old.

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Side Effects

What are the side effects of Azithromycin (Zithromax)?

Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning in your eyes, skin pain, red or purple skin rash that spreads and causes blistering and peeling).

Seek medical treatment if you have a serious drug reaction that can affect many parts of your body. Symptoms may include: skin rash, fever, swollen glands, muscle aches, severe weakness, unusual bruising, or yellowing of your skin or eyes.

Call your doctor at once if you have:

  • severe stomach pain, diarrhea that is watery or bloody;
  • fast or pounding heartbeats, fluttering in your chest, shortness of breath, and sudden dizziness (like you might pass out); or
  • liver problems--nausea, vomiting, loss of appetite, stomach pain (upper right side), tiredness, itching, dark urine, clay-colored stools, jaundice (yellowing of the skin or eyes);

Call your doctor right away if a baby taking azithromycin becomes irritable or vomits while eating or nursing.

Older adults may be more likely to have side effects on heart rhythm, including a life-threatening fast heart rate.

Common side effects may include:

  • nausea, vomiting; or
  • stomach pain.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

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Pregnancy & Breastfeeding

Can I take Azithromycin (Zithromax) if I’m pregnant or breastfeeding?

It is not known whether this medicine is effective in treating genital ulcers in women.

Tell your doctor if you are pregnant or breastfeeding. Taking azithromycin while breastfeeding may cause diarrhea, vomiting, or rash in the nursing baby.

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What drugs and food should I avoid while taking Azithromycin (Zithromax)?

Antibiotic medicines can cause diarrhea, which may be a sign of a new infection. If you have diarrhea that is watery or bloody, call your doctor before using anti-diarrhea medicine.

Azithromycin could make you sunburn more easily. Avoid sunlight or tanning beds. Wear protective clothing and use sunscreen (SPF 30 or higher) when you are outdoors.

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Dosage Guidelines & Tips

How to take Azithromycin (Zithromax)?

Use Azithromycin (Zithromax) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Azithromycin oral is taken by mouth. Azithromycin injection is given as an infusion into a vein, usually for 2 days before you switch to azithromycin oral. A healthcare provider will give you this injection.

You may take azithromycin oral with or without food.

Shake the oral suspension (liquid) before you measure a dose. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).

Use this medicine for the full prescribed length of time, even if your symptoms quickly improve. Skipping doses can increase your risk of infection that is resistant to medication. Azithromycin will not treat a viral infection such as the flu or a common cold.

Store at room temperature away from moisture and heat. Throw away any unused liquid medicine after 10 days.

What should I do if I missed a dose of Azithromycin (Zithromax)?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

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Overdose Signs

What happens if I overdose on Azithromycin (Zithromax)?

If you think you or someone else may have overdosed on: Azithromycin (Zithromax),  call your doctor or the Poison Control center
(800) 222-1222
If someone collapses or isn't breathing after taking Azithromycin (Zithromax), call 911
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What to Expect

You should start to feel better within a few days of taking azithromycin, but this will depend on the type of infection you have.

Let your doctor know if you don’t improve or feel worse after using this medicine.

Finish the whole course of azithromycin. Don’t stop taking this medicine, even if your symptoms subside.

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Additional Dosage Information

Your dosage will depend on your medical condition, your age, the formulation of azithromycin you use, and other factors.

A typical dosage of immediate-release azithromycin for adults might be 500 milligrams (mg) a day on day one, followed by 250 mg a day on days two to five.

If your doctor prescribes the extended-release form of azithromycin, you may take 2 grams (g) once as a single dose.

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Secondary Uses

Azithromycin is used to treat a variety of infections. Your doctor may recommend it for conditions that aren’t listed in this medical guide.

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Medical Disclaimer

Drugs A-Z provides drug information from Everyday Health and our partners, as well as ratings from our members, all in one place. Cerner Multum™ provides the data within some of the Overview, Uses, Warnings, Side Effects, Pregnancy, Interactions, Dosage, Overdose, and Images sections. The information within all other sections is proprietary to Everyday Health.