What is Azithromycin: Uses, Warnings & Interactions

Updated May 14, 2025  •  Published Dec 30, 2020

Azithromycin is a common prescription antibiotic used to treat a range of familiar bacterial infections including pneumonia and sexually transmitted diseases (STDs). Like all antibiotics, it is only used for a short time to eradicate infections. As a macrolide antibiotic, azithromycin’s side effects are common and some can be severe, so people taking azithromycin should know some of the warning signs of important adverse reactions.

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Azithromycin overview

BRAND NAMES:

  • Zithromax, Zithromax Z-Pak, Azasite

Generic Names:

  • Azithromycin, azithromycin monohydrate, azithromycin dihydrate

Uses:

  • Treats bacterial infections.

Therapeutic Classes:

  • Antibiotic, macrolide

Forms:

  • Tablet, oral suspension (liquid), packets for oral suspension, injection, eye drops

How it’s taken:

  • By mouth

What is Azithromycin used for?

Azithromycin treats a broad spectrum of mild to moderate bacterial infections including bacterial pneumonia, strep throat, bronchitis, sinusitis, middle ear infections, skin infections, chlamydia, gonorrhea, pelvic inflammatory disease, and genital ulcers.

What form(s) does Azithromycin come in

  • Tablet

    • 250 mg

    • 500 mg

    • 600 mg

  • Oral suspension (liquid)

    • 100 mg/5 mL

    • 200 mg/5 mL

  • Packets for oral suspension

    • 1 g/packet

    • Injection

  • 500 mg/vial

    • Eye drops

  • 1% (10 mg/mL)

What are common Azithromycin doses?

  • For bacterial infections in adults including pneumonia and strep throat: 500 mg dose on day 1 followed by 250 mg per day for four days

  • For gonorrhea in adults: 1 gram single dose

  • For genital ulcers (chancroid) or chlamydia in adults: 2 gram single dose

  • For pelvic inflammatory disease: 500 mg IV injection per day for one to two days followed by 250 mg per day taken by mouth for five to six days

  • For bacterial sinusitis: 500 mg daily for three days

  • For mycobacterium lung infection: 500–600 mg per day

  • For middle ear infections (otitis media) in children: 30 mg/kg as a single dose OR 10 mg/kg daily for three days

  • For strep throat in children: 12 mg/kg daily for five days

  • For bacterial conjunctivitis: 1 drop in each eye twice daily for two days then 1 drop in each eye daily for five days

  • For children’s dosages and other indications, find more details about Zithromax dosage, forms, and strengths here.

Common Azithromycin prescriptions

  • Azithromycin
    15ml of 100mg/5ml bottle

  • Azithromycin
    15ml of 200mg/5ml bottle

  • Azithromycin
    22.5ml of 200mg/5ml bottle

  • Azithromycin
    30ml of 200mg/5ml bottle

  • Azithromycin
    3 tablets box

  • Azithromycin
    6 tablets box

  • Azithromycin
    3 tablets disp pack

  • Azithromycin
    6 tablets disp pack

  • Azithromycin
    1gm packet

  • Azithromycin
    500mg solution reconstituted

  • Azithromycin
    250mg tablet

  • Azithromycin
    500mg tablet

  • Azithromycin
    600mg tablet

How to take Azithromycin

  • Your doctor will tell you how much medicine to use. Do not use more than directed.

  • Take all of the medicine in your prescription to clear up your infection, even if you feel better after the first few doses.

  • Read and follow the patient instructions that come with this medicine. 

  • How to take azithromycin tablets

    • Azithromycin tablets can be taken with or without food.

    • Swallow the tablet whole. 

    • Store azithromycin tablets at room temperature.

  • How to take azithromycin oral suspension

    • Azithromycin oral suspension can be taken with or without food.

    • Shake the bottle before opening it and measuring a dose.

    • Use a calibrated oral syringe or other medicine-measuring device. If it’s missing, a pharmacist can provide one for free. Do not use kitchen or table utensils to measure out a dose.

    • Store azithromycin oral suspension in a closed bottle at room temperature.

  • How to take azithromycin packets for oral suspension

    • You will only use one or two packets in total.

    • Use one packet per day.

    • Open the packet and pour all of the powder into a glass.

    • Add 2 ounces (1/4 cup) of water and mix

    • Drink the medicine right away.

    • Add 2 more ounces of water into the same glass and mix.

    • Drink the remaining mixture.

    • Store unopened azithromycin packets at room temperature.

  • How to take azithromycin eye drops (AzaSite)

    • Read the Instructions for Use that come with this medicine.

    • Wash your hands with soap and water before applying a dose.

    • Hold the bottle upside down and shake the bottle.

    • Remove the tan cap.

    • Tilt your head back.

    • Squeeze one drop on each infected.

    • Replace the cap.

    • Store the eye drops in the original closed bottle at room temperature.

What to do if you miss a dose of Azithromycin

  • If you keep forgetting doses, talk to a healthcare provider or pharmacist about tools that can help you remember.

  • Take a missed dose as soon as it’s remembered. However, if it is almost time for the next dose, skip the missed dose and take the next scheduled dose on time. 

  • Do not take extra medicine to make up for a missed dose.

Azithromycin contraindications

  • This medicine is not right for everyone. 

  • Do not use it if you have had an allergic reaction to azithromycin, erythromycin, or similar medicines.

  • Do not use azithromycin if you have a history of liver problems caused by azithromycin.

Azithromycin warnings

  • Tell any doctor or other healthcare provider who treats you that you are using this medicine.

  • Your doctor may need to examine you or perform blood tests to monitor the effects of this medicine. Keep all appointments.

  • Call your doctor if your symptoms do not improve or if they get worse.

  • Tell your doctor if you are pregnant or breastfeeding.

  • Before taking azithromycin, inform the prescriber about any medical conditions you may have, particularly:

    • Liver disease

    • Kidney disease

    • Heart rhythm problems

    • Heart failure

    • Any recent heart attack

    • Myasthenia gravis

    • Any bacterial infection of the blood

    • Any infection caught in a hospital

    • Cystic fibrosis

    • Pneumonia

    • Weakened immune system

  • This medicine may cause the following problems: 

    • Liver damage

    • Heart rhythm irregularities

    • Swollen pancreas

    • Worsening of myasthenia gravis

  • This medicine can cause diarrhea due to bacterial overgrowth in the intestines. It may occur 2 months or more after you stop taking this medicine. Call your doctor if the diarrhea becomes severe, does not stop, or is bloody. Do not take any medicine to stop diarrhea until you have talked to your doctor.

  • This medicine can cause digestive system blockage in newborns. Symptoms include vomiting and irritability when feeding.

Azithromycin interactions

  • To avoid potentially hazardous drug interactions, tell the prescribing healthcare provider about all prescription drugs, over-the-counter medications, and supplements you use before taking azithromycin.

  • Tell other healthcare providers you are using this medicine before they prescribe new medications.

  • Do not take an antacid that contains magnesium or aluminum at the same time you take an oral dose of azithromycin. 

  • Some drugs may cause problems when taken with azithromycin. Make sure to tell the prescribing healthcare professional if you are currently taking:

    • Blood thinners

    • Heart rhythm drugs

    • Statins

    • Migraine medications called ergots

    • The heart failure drug digoxin

    • The immune suppressant cyclosporine

    • The antiseizure medication phenytoin

    • The HIV/AIDS drug nelfinavir

    • The gout treatment colchicine

    • The antipsychotic medications pimozide and thioridazine

  • Avoid alcohol when taking azithromycin.

  • Find out more about azithromycin interactions to avoid here.

Azithromycin side effects

Serious side effects

Talk to a doctor if you notice any signs or symptoms of a possible serious side effect including:

  • Severe diarrhea, bloody diarrhea, stomach cramps, fever

  • Dark urine, pale stools, nausea, vomiting, loss of appetite, stomach pain, yellow skin or eyes

  • Fast, pounding, or uneven heartbeat, chest pain

  • Feeling irritable or vomiting after feeding (in very young babies)

  • Blistering, peeling, red skin rash

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing

Less serious side effects

  • Nausea

  • Mild diarrhea

  • Abdominal pain

  • Vomiting

  • Injection site reactions such as burning, pain, or irritation (injection)

  • Eye irritation (azithromycin eye drops)

Find more detailed information about azithromycin side effects here.

Sources:

Azithromycin News & Research

Azithromycin stomach pain: What to expect and how to manage it

Azithromycin side effects in kids: What parents should know

Does azithromycin make you tired? How to avoid fatigue

Can you take ibuprofen with azithromycin?

Can dogs take azithromycin?

How is azithromycin used in cats

Azithromycin interactions to avoid

Azithromycin (Zithromax) alternatives: What can I take instead of azithromycin?

Azithromycin side effects and how to avoid them

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