Z-Pak: When Do You Take Your Second Dose?

In our latest question and answer, the pharmacist discusses when you are supposed to take your second dose of a Z-Pak.


If I take the first two azithromycin pills at 7 pm, should I wait until 7 pm the next day and subsequent days to take my single pill doses?

Asked by Warren On Feb 18, 2022

Answered by
Medical Content Reviewed By HelloPharmacist Staff

Published Feb 22, 2022
Last updated Mar 03, 2022

Key points

  • The Z-Pak is a five-day course of the antibiotic azithromycin.
  • Each dose of the Z-Pak is taken once a day. Therefore, the second dose is taken 24 hours (one day) after the first dose.

Hello and thanks for reaching out to us!

I'm more than happy to go over how to properly take a Z-Pak and when you should be taking your second dose.

Just to get right into it, each dose of a Z-Pak is to be taken 24 hours apart (i.e. one dose per day).

Therefore, if you took your first dose at 7 PM in the evening, you should take your second dose at 7 PM the next evening.

This is how all five doses should be taken.

Z-Pak: Full Directions

ZPak Showing Directions On Box

A 'Z-Pak' is a five-day course of the antibiotic azithromycin, which is classified as a macrolide antibiotic.

There are 6 total tablets in a Z-Pak, and each tablet contains 250mg of azithromycin.

The Z-Pak should be taken the following way (unless otherwise directed by your prescriber):

  • Take two tablets (500mg) as one dose on the first day
  • Take one tablet (250mg) daily for four more days

So, overall, you are taking the medication for 5 days, with 24 hours (one full day) between doses.

Why Two Tablets On Day One?

I've had some recent questions wondering why you take two tablets on the first day, but only one for each of the next four days.

The answer is that the first dose acts as a 'loading dose' and allows the drug to reach high enough concentrations in your system to be effective.

Each of the next four days' doses keeps the drug concentration at that high, effective, level.

We wrote about this in a little more detail on another one of our answer pages, which can be found here: Why Do You Take Two Tablets On Day One?

Additional Information

It is important to note as well that azithromycin is still working long after you take your last dose due to its extremely long half-life, which is reported to be around 68 hours.

Even when you are 2-3 days out from taking your last dose, the drug is still in your system acting as an antibiotic, so you shouldn't be overly worried if you are still having symptoms after your last dose.

Having said that, if you are still not feeling better at all a few days after finishing, be sure to reach out to your provider.

HelloPharmacist has a comprehensive drug page for azithromycin, which lists side effects, drug interactions, and more, and can be found here: HelloPharmacist 'Zithromax' Drug Information


  • Azithromycin Prescribing Information, AccessFDA
  • Azithromycin. A review of its antimicrobial activity, pharmacokinetic properties, and clinical efficacy, PubMed
  • Azithromycin: mechanisms of action and their relevance for clinical applications., PubMed

About the Pharmacist

Dr. Brian Staiger, PharmD

Dr. Brian has been practicing pharmacy for over 11 years and has wide-ranging experiences in many different areas of the profession. From retail, clinical and administrative responsibilities, he's your knowledgeable and go-to source for all your pharmacy and medication related questions!

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