Despite its easy dosing schedule and effectiveness against many different types of infections, Zithromax may put its users at a risk for kidney problems.

Zithromax is the brand name for the drug azithromycin, sold by manufacturer Pfizer Inc. Pfizer first acquired FDA approval for azithromycin under the name Zithromax in 1991.

Since Zithromax is effective against many common pathogens, it’s indicated for a wide variety of uses. The FDA now approves Zithromax as a treatment for infections throughout the respiratory tract, sexually transmitted diseases, genital ulcer disease in men, mycobacterial infections, and infections of the skin or soft tissue.

Zithromax has also seen some off-label use for other conditions, such as pelvic inflammatory disease, dental infections, acne, or the acute diarrhea that sometimes afflicts travelers.

Unlike other antibiotics, Zithromax can be effective in much shorter courses. This is attributable to the drug’s unusually long half-life, (the measure of the amount of time it stays active in the human body). Because it stays active for such a long time, Zithromax can be effective with much fewer doses than are needed with other antibiotics.

To that end, Pfizer markets azithromycin in a ready-to-dispense pack known as Zithromax Z-pak. These are pre-packaged packs that contain the exact number of tablets the patient will need for a course of just a few days. Zithromax Z-pak comes in packs for three-day and five-day courses. A three-day Zithromax Z-pak can be used to treat the majority of infections.

Zithromax Side Effects

Unfortunately,it is not without Zithromax side effects, and some of them can be serious. Zithromax adverse effects can include kidney  problems that can lead to hospitalization and in very rare cases permanent kidney failure.

Pfizer’s own product information indicated that reports of Zithromax side effects have included instances of renal problems. Some patients presented with elevated serum creatinine and blood urea nitrogen, both signs of possible impaired kidney function. A few patients developed interstitial nephritis and acute renal failure.

Interstitial nephritis is an inflammation of the tubules inside the kidneys. Symptoms of nephritis can include fever, rash or excessive urination. It often results in kidney failure, or the loss of most kidney function. The product information for Zithromax states that in at least one case, interstitial nephritis that occurred in a patient taking azithromycin led to permanent renal failure.

A case study published in the Clinical Kidney Journal in June 2011 tells the story of a 16-year-old girl who suffered interstitial nephritis induced by azithromycin. The girl went to the emergency room after ten days of vomiting, fatigue and abdominal pain. She reported having taken no other medications other than a six-day course of azithromycin she had received two weeks before.

Based on her lab results, evidence of renal failure, and the results of a kidney biopsy, she was diagnosed with acute interstitial nephritis. Her doctor believed her nephritis was related to the azithromycin she had taken a few weeks before, noting two other cases of nephritis that led to persistent renal injury after treatment with azithromycin. The girl did not recover her full kidney function until after weeks of treatment.

Patients who suffered similar kidney problems after a course of Zithromax have the option of discussing possible legal remedies with an attorney familiar with Zithromax side effects lawsuits.