Accidentally Missed Doses Of Z-Pak (Azithromycin)

Answer

Missing doses of an antibiotic, like azithromycin, could make it less effective and potentially lead to antibiotic resistance, making future infections more difficult to treat.

One of the most important aspects of successful therapy with azithromycin is completing the entire dosage as directed, which is:

• Two tablets (500mg) by mouth on day one
• One tablet (250mg) by mouth on days two through five

The total course consists of 1500 mg (6 tablets of 250 mg).

The first two-tablet dose is known as a 'loading dose', which allows the antibiotic to reach a sufficient concentration in the body to start working. Each subsequent dose keeps the antibiotic at that effective concentration.

Missing Doses

In most cases, missing antibiotic doses likely makes them less effective. This is probably the case with azithromycin as well to some degree but this antibiotic is a little more forgiving than others since each dose lasts an extremely long time.

The half-life of azithromycin is 68 hours, which is the time it takes you to metabolize 50% of the drug.

It takes approximately 14 days for azithromycin to be completely eliminated from your system. In other words, the antibiotic hangs around in your body for a long time, and even after missing a dose or two, the drug is still in your system working to eliminate your infection.

When you miss a dose with a Z-Pack, as you have, it is very important to still complete the entire course of therapy (6 tablets of 250 mg).  Therefore, it is important to continue on the dosing schedule (once daily) and finish the entire pack. Finishing the course in the subsequent days would probably still clear the infection you are treating.

However, If the infection doesn’t seem to be improving, it is important to consult your prescriber to determine the next steps.

I do want to say that it is difficult to know precisely whether or not missing a dose of azithromycin reduces how effective the antibiotic is, as I couldn't find any specific data regarding this. It stands to reason that not taking the drug as intended will result in it not being as effective as it would be if it were taken correctly, but as I've written in this answer, the long half-life of the drug makes missing a dose less of an issue when compared to other antibiotics.

Azithromycin Is Still Working After Taking Your Last Dose

It is not uncommon to not feel better after completing therapy with azithromycin. As described above, the drug lasts a long time in the body and continues to work for days after your Z-Pack is finished. If your symptoms don't seem to be improving after about a week or two, contact your doctor.

Z-Pak Info

A Z-pak consists of six tablets of azithromycin 250 mg. Usually, two tablets are prescribed on the first day of therapy, followed by one tablet for the following four days.

Azithromycin is a macrolide antibiotic that can treat a variety of infections including bronchitis, sinus infections, ear infections, skin infections, sexually transmitted infections, and more. Azithromycin can cover several types of bacteria but is not effective in treating the flu, the common cold, or other viral infections.

Like most antibiotics, azithromycin may cause diarrhea, nausea, vomiting, and abdominal pain. Macrolides are more likely to cause these types of side effects, but azithromycin is one of the more tolerable drugs in the class.

Another concern with azithromycin is that it can cause QT prolongation in patients with a past medical history related to the heart. Drug interactions can also be a concern so always check each new medication prior to starting a new therapy.

Final Words

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