AntibioticsGenerally, switching antibiotics should only be done under the guidance of a physician or other health care provider. Discontinuing antibiotics prior to completion of the full course can lead to resistance. If the infection doesn’t seem to be improving, it is important to consult the prescriber to determine the next steps.

Azithromycin (Z-Pak) and levofloxacin (Levaquin) are two commonly used antibiotics for similar indications including pneumonia, bronchitis, sinusitis, and more. Both are considered broad spectrum antibiotics that cover against many gram-positive and gram-negative bacteria.

There is a significant drug interaction between azithromycin and levofloxacin. Taking these together may cause an increased risk of QT prolongation, a rare heart condition that can be fatal. We will discuss more about these two drugs below.

The half-life of levofloxacin is about 6 to 8 hours. Therefore, it would take about 24-36 hours to clear from the bloodstream after the last dose. After this time, the risk of QT prolongation with these drugs would be significantly lessened.

Information About Levofloxacin

Levofloxacin is a fluoroquinolone antibiotic and is in the same class as ciprofloxacin (Cipro) and moxifloxacin (Avelox). It is commonly prescribed for respiratory conditions and is available as an oral tablet and an intravenous formulation.

Fluoroquinolones can cause side effects including GI upset, tendon or joint disorders, and confusion. Levofloxacin can also rarely cause photosensitivity and exposure to sunlight should be avoided during treatment.


Information About Azithromycin

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.