Z-Pak Dosages for Kids and Adults: Your GoodRx Guide

There’s a good chance you’ve been prescribed, or at least heard of, a Z-Pak. It contains a “pack” or blister card with six tablets of azithromycin (Zithromax). This is a macrolide antibiotic that prevents the growth of certain bacteria. Azithromycin has been around for decades and is generally well tolerated.

Z-Paks can treat a variety of mild to moderate bacterial infections, such strep throat, pneumonia, and ear infections. Azithromycin’s dosages are the same for many people. So the pre-packaged, ready-to-use Z-Pak allows for a convenient way to prescribe, fill, and take the medication. But a few things can still affect your Z-Pak dosage, such as your age and other medications you take.

Here, we’ll review the recommended Z-Pak dosage for adults and children. Keep in mind that azithromycin also comes in other forms with different dosing schedules, so be sure to follow your prescriber’s instructions carefully.

What’s the typical Z-Pak dosage for adults?

A Z-Pak contains six 250 mg azithromycin tablets. These tablets are taken for 5 days in a row. The Z-Pak dosage on the first day of treatment is typically 2 tablets (500 mg total) by mouth as a single dose. On days 2 through 5, you’ll take just 1 tablet (250 mg) per day.

You can take azithromycin with or without food. But if you experience diarrhea or an upset stomach after taking it, try taking your next dose with food to help minimize these side effects.

The Z-Pak is different from the Tri-Pak, which contains three 500 mg tablets of azithromycin. The Tri-Pak dosage is 1 tablet daily for 3 days.

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Azithromycin is also available as loose tablets (similar to other prescription tablets without the dose pack) as well as an oral suspension, among other non-oral dosage forms. Your prescriber will decide which form of azithromycin is best to treat your infection.

Good to know: You may start to feel better after a few days of taking azithromycin. But you should still continue to take the full course of your antibiotic. Stopping a Z-Pak early can lead to an undertreated infection and antibiotic resistance. This means a Z-Pak may not work as well for you the next time you take it for an infection.

What’s the typical Z-Pak dosage for children?

Azithromycin can also treat bacterial infections in children age 6 months and older. But for tonsil infections and strep throat, it isn’t recommended for children under age 2.

The azithromycin dosage for children is based on the child’s body weight. Children who weigh 50 kg (110 lbs) or more can follow the adult Z-pak dosage. But in most cases, children are prescribed azithromycin suspension (liquid).

There isn’t a liquid version of a Z-Pak. But your prescriber may recommend a similar dosing schedule using the suspension, with a higher dose on the first day and a lower dose for days 2 through 5.

For example, a typical dose of azithromycin for an ear infection is 10 mg per kilogram of body weight on the first day, followed by 5 mg per kilogram of body weight on days 2 through 5. For a child weighing 20 kg (44 lbs), this would equate to a 200 mg dose on day 1 and a 100 mg dose days 2 through 5. For the azithromycin suspension containing 200 mg of medication per 5 mL, this means you would measure a 5 mL dose on day 1 followed by 2.5 mL doses on days 2 through 5. 

This may seem complex, but rest assured your healthcare team will make all of the necessary calculations. Your prescriber and pharmacist will also review the exact dosage measurement for your child with you when it’s prescribed. But don’t hesitate to reach out with any questions that arise during treatment.

Are there any Z-Pak dosage adjustments for medical conditions?

There aren’t any medical conditions that require Z-Pak dose adjustments. However, caution is needed when azithromycin is prescribed to people with certain medical conditions, such as liver and heart problems.

Before taking azithromycin, notify your prescriber if you have a history of liver problems. Z-Paks should be avoided altogether if you have a history of severe liver dysfunction or jaundice (yellowing of the skin or eyes). 

Z-Paks can also cause long QT syndrome, a condition when your heart takes more time to reset during beats. This isn’t common, but it can be life-threatening. The risk of QT prolongation is higher when azithromycin is combined with certain health conditions, such as other heart rhythm problems, or medications such as amiodarone (Pacerone).

You can help prevent these interactions by telling your healthcare team about your health history as well as all medications you’re currently taking. But if you experience a fast or irregular heartbeat, chest pain, or dizziness while taking a Z-Pak, seek medical care right away.

What happens if you miss a dose of azithromycin?

Taking your antibiotic consistently helps maximize its effectiveness. So if you miss a dose of your Z-Pak, take it as soon as you remember. But if it’s close to the time of your next scheduled dose, it’s best to skip it and take your next dose as planned. Don’t double up on doses to make up for the one you missed. But you should still take all of the tablets in the Z-Pak. You may just need to add an extra day onto your original schedule if you miss a dose.

Taking your medication at the same time every day is a helpful way to remember to take it consistently. There are also tools that can help you remember to take it on time and as planned. For example, setting an alarm for a certain time of day (like after a meal) can be helpful. Medication reminder apps are also useful options.

What should you do if you take too much azithromycin?

Since it comes in a blister pack, it should be relatively easy to tell if you’ve already taken your Z-Pak dose for the day. But if you accidentally take an extra dose by mistake, it’s unlikely to cause any harm. In fact, higher azithromycin doses (up to 2 grams) are actually prescribed for certain infections. But you may experience more side effects after an extra dose, such as diarrhea, nausea, and stomach pain.

If you believe you or your child has taken too much azithromycin, it’s best to contact your prescriber as a precaution. They can determine next steps and guide you appropriately depending on the situation. Contacting Poison Control online or at 1-800-222-1222 is another option. But if you’re experiencing severe symptoms, it’s best to seek emergency care right away instead.  

How to save on your Z-Pak

The “Z-Pak” is a nickname for the prepackaged form of azithromycin, and it’s available both as a brand-name and generic medication. GoodRx can help you save over 80% off the average retail price of the generic version.

The price of a generic Z-Pak (azithromycin) is as low as $9.38 at certain pharmacies with a free GoodRx discount. And the price of a 15 mL bottle of generic azithromycin suspension is as low as $13.66 with GoodRx.

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Written by:

Cassandra Pardini, PharmD, MS

Cassandra Pardini has been a freelance medical writer for 7 years. In that time, she has concentrated on publishing articles on medication-related information for healthcare professionals and patients.

Edited by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

Reviewed by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

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