Azithromycin belongs to the family of medications known as macrolide antibiotics. It is used to treat certain types of infections that are caused by bacteria. It is most commonly used to treat ear infections (e.g., otitis media), throat infections, lung infections (e.g., pneumonia), certain sexually transmitted infections, and skin infections. It can also be used to prevent mycobacterium avium complex (MAC) infections in people with HIV infection and to treat flare-ups of chronic obstructive pulmonary disease (COPD) caused by bacteria.

Your doctor may have suggested this medication for conditions other than the ones listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are being given this medication, speak to your doctor. Do not stop using this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to use this medication if their doctor has not prescribed it.

The dose of azithromycin depends on the condition being treated.

The recommended adult dose of azithromycin for treatment of lung and skin infections is 500 mg (as two 250 mg tablets taken on the first day), followed by one 250 mg tablet taken at the same time each day for 4 more days. When treating flare-ups of COPD, azithromycin can also be taken as two 250 mg tablets once daily for 3 days. Genitourinary tract infections can be treated with a single dose of 1000 mg (4 tablets of 250 mg) or 2000 mg (8 tablets of 250 mg), depending on the type of bacteria causing the infection and the type of infection.

The usual dose for prevention of mycobacterium avium complex (MAC) infections in people with HIV infection is 1200 mg taken once weekly.

The children's dose of azithromycin (liquid suspension) is based on body weight. When used to treat otitis media (middle ear infection) in children, a course of treatment of either 1 day, 3 days, or 5 days may be used. The daily dose will vary depending on the number of treatment days. Use an oral syringe to measure each dose of the liquid, as it gives a more accurate measurement than household teaspoons.

Azithromycin may also be given by injection to treat severe pneumonia or pelvic inflammatory disease. It is usually given in a hospital setting by a health professional. Your doctor will determine the appropriate dose of this medication.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones given here, do not change the way that you are taking the medication without consulting your doctor.

Azithromycin must be taken for the recommended duration of treatment, even if you are feeling better. This will reduce the chances of having remaining bacteria grow back.

The medication may be taken with or without food. Taking the medication with food may help to avoid stomach upset.

It is important to take this medication exactly as prescribed by your doctor. Finish all of this medication, even if you start to feel better. If you miss a dose, take it as soon as possible and continue on with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store all forms of this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children. Discard any unused suspension (liquid) after 10 days.

Tablets

250 mg
Each pink, film-coated, modified capsule-shaped tablet, engraved "Pfizer" on the upper face and "306" or scored on the other, contains azithromycin dihydrate equivalent to 250 mg of azithromycin. Nonmedicinal ingredients: pregelatinized starch, anhydrous calcium phosphate dibasic, sodium croscarmellose, magnesium stearate, sodium lauryl sulphate, hydroxypropyl methylcellulose, lactose (tablet coating), titanium dioxide, triacetin, and D&C Red No. 30 Aluminum Lake.

600 mg
Each white, modified capsule-shaped, film-coated tablet, engraved on front with "Pfizer" and "308" or scored on the other, contain azithromycin dihydrate equivalent to 600 mg. Nonmedicinal ingredients: anhydrous calcium phosphate dibasic, pregelatinized starch, sodium croscarmellose, magnesium stearate, sodium lauryl sulphate, hydroxypropyl methylcellulose, lactose (tablet coating), titanium dioxide, and triacetin. 

Powder for Oral Suspension

After reconstitution, each bottle of cherry-flavoured suspension contains azithromycin dihydrate equivalent to 300 mg per 15 mL (100 mg/5 mL), or 600 mg per 15 mL (200 mg/5 mL), or 900 mg per 22.5 mL (200 mg/5 mL). Nonmedicinal ingredients: artificial flavors, FD&C Red No. 40, sodium phosphate, sucrose, tribasic hydroxypropyl cellulose, and xanthan gum.

Do not take azithromycin if you:

• are allergic to azithromycin or any ingredients of the medication
• are allergic to erythromycin or other macrolide antibiotics (e.g., clarithromycin)
• have had liver problems caused by taking azithromycin in the past

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• diarrhea (mild)
• headache
• nausea
• pain, redness, or swelling at the injection site (injection only)
• stomach pain or discomfort
• vaginal irritation (e.g., increased discharge, itching, irritation, painful urination)
• vomiting

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
• signs of myasthenia gravis (e.g., muscle weakness, vision changes, difficulty chewing and swallowing)
• symptoms of irregular heartbeat (e.g., chest pain; dizziness; rapid, pounding heartbeat; shortness of breath)

Stop taking the medication and seek medical attention immediately if any of the following side effects occur:

• abdominal or stomach cramps or pain (severe)
• diarrhea (watery and severe, which may be bloody)
• signs of a severe allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
• symptoms of blockage in the digestive tract (e.g., irritability when feeding, projectile vomiting) – children only
• symptoms of a severe skin reaction (e.g., blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Abnormal heart rhythms: This medication can cause abnormal heart rhythms. Certain medications (e.g., sotalol, chlorpromazine, pimozide, moxifloxacin, mefloquine, pentamidine, arsenic trioxide, tacrolimus) can increase the risk of a type of abnormal heart rhythm called QT prolongation, and should not be used in combination with azithromycin. You are more at risk for this type of abnormal heart rhythm and its complications if you:

• are female
• are older than 65 years of age
• have a family history of sudden cardiac death
• have a history of heart disease or abnormal heart rhythms
• have a slow heart rate
• have congenital prolongation of the QT interval
• have diabetes
• have had a stroke
• have low potassium, magnesium, or calcium levels
• have nutritional deficiencies

If you have heart disease and abnormal heart rhythms, or are taking certain medications (e.g., verapamil, atazanavir), discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Antibiotic-associated colitis: This medication, like other antibiotics, may cause a potentially dangerous condition called antibiotic-associated colitis or pseudomembranous colitis. Symptoms include severe, watery diarrhea that may be bloody. If you notice these symptoms, stop taking azithromycin and contact your doctor as soon as possible.

Bacterial resistance: Misuse of an antibiotic such as azithromycin may lead to the growth of resistant bacteria that will not be killed by the antibiotic. If this happens, azithromycin may not work for you in the future. Although you may begin to feel better early in your course of treatment with azithromycin, you need to take the full course exactly as directed to finish ridding your body of the infection and to prevent resistant bacteria from taking hold. Do not take azithromycin or other antibiotics to treat a viral infection such as the common cold; antibiotics do not kill viruses, and using them to treat viral infections can lead to the growth of resistant bacteria.

Kidney disease: If you have kidney disease or reduced kidney function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver disease: The liver is responsible for removing most of the azithromycin from the body. If it is not working properly, there is an increased risk of side effects of the medication. If you have liver disease or reduced liver function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

This medication may also cause a decrease in liver function. If you experience symptoms of liver problems such as fatigue, feeling unwell, loss of appetite, nausea, yellowing of the skin or whites of the eyes, dark urine, pale stools, abdominal pain or swelling, and itchy skin, contact your doctor immediately.

Myasthenia gravis: Myasthenia gravis is a condition that causes specific muscle weakness. Azithromycin may cause the symptoms of myasthenia gravis to flare up. If you have myasthenia gravis, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Overgrowth of organisms: Prolonged or repeated use of azithromycin may result in an overgrowth of bacteria or fungi and organisms that are not killed by the medication. This can cause other infections, such as yeast infections, to develop.

Pregnancy: The safety of azithromycin for use by pregnant women has not been established. This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking azithromycin it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and efficacy of azithromycin tablets or suspension have not been established for treating children younger than 6 months of age who have acute otitis media or community-acquired pneumonia.

The safety and efficacy of azithromycin tablets or suspension have not been established for treating children younger than 2 years of age who have throat infections or tonsillitis.

The safety and efficacy of azithromycin injection have not been established for children less than 16 years of age.

There may be an interaction between azithromycin and any of the following:

• aliskiren
• antacids (e.g., aluminum hydroxide, calcium carbonate, magnesium hydroxide) – separate antacids and azithromycin by at least 2 hours
• antiarrhythmics (e.g., amiodarone, dronedarone)
• anticancer drugs (e.g., capecitabine, doxorubicin, etoposide, topotecan, vincristine)
• antipsychotics (e.g., chlorpromazine, clozapine, haloperidol, olanzapine, quetiapine, risperidone)
• "azole" antifungals (e.g., fluconazole, voriconazole)
• bacillus Calmette-Guérin (BCG)
• beta-adrenergic blockers (e.g., nadolol, sotalol)
• cholera vaccine
• colchicine
• cyclosporine
• dabigatran
• digoxin
• domperidone
• edoxaban
• everolimus
• general anesthetics (medications used to put people to sleep before surgery)
• hepatitis C antiviral medications (e.g., glecaprevir, pibrentasvir)
• macrolide antibiotics (e.g., clarithromycin, erythromycin)
• methadone
• monoclonal antibodies (e.g., atezolizumab, ipilimumab)
• morphine
• naloxegol
• pentamidine
• procainamide
• propafenone
• protein kinase inhibitors (e.g., ceritinib, crizotinib, dabrafenib, dasatinib, nilotinib, sunitinib)
• quinolone antibiotics (e.g., levofloxacin, moxifloxacin)
• ranolazine
• rifaximin
• selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, escitalopram)
• silodosin
• sirolimus
• sodium picosulfate
• "statin" anti-cholesterol medications (e.g., atorvastatin, lovastatin, simvastatin)
• tacrolimus
• tenofovir
• tricyclic antidepressants (e.g., clomipramine, doxepin, imipramine)
• typhoid vaccine
• warfarin

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.