Although Zithromax is widely used and often without incident, studies show it can be linked to kidney complications that in the most severe cases could result in permanent damage.

Zithromax can treat a wide range of bacterial infections. It’s approved as a treatment for respiratory infections, sexually transmitted diseases, and skin infections. It’s one of a class of antibiotics called macrolides, which work by inhibiting bacteria’s ability to grow.

The same ingredient in Zithromax is sometimes packaged in a single time-released dose under the brand name Zmax and in short (usually three- or five-day) courses under the brand name Z-Pak.

Zithromax and Kidney Failure

One recent case study published in the November 2015 issue of Pharmacotherapy tells the story of a 59-year-old man who suffered from kidney complications after taking Zithromax, referred to in the study by its generic name azithromycin.

He sought medical treatment for his kidney symptoms two weeks after completing a five-day course of azithromycin for an upper respiratory condition. He complained of three days’ worth of nausea, vomiting, fever and malaise, and he had not produced any urine in the previous 24 hours.

Lab results showed signs of possible renal failure, and a kidney biopsy confirmed he was suffering from acute interstitial nephritis. Analysis by his physicians confirmed there was a definite relationship between his kidney problems and the azithromycin he had recently taken.

Similar trouble befell a 16-year-old girl who had taken azithromycin for bronchitis. Two weeks after taking her azithromycin, she went to the emergency room complaining of sickness, fatigue, vomiting, malaise and abdominal pain.

Her lab work showed abnormal levels of creatinine and blood urea nitrogen, two possible signs of kidney failure. She was diagnosed with acute interstitial nephritis, confirmed by a kidney biopsy. It took a total of about six weeks for her to completely recover her kidney function.

What Is Acute Interstitial Nephritis?

Both these patients were diagnosed with the same kidney condition: acute interstitial nephritis. Most commonly, this condition results from a reaction to a drug like Zithromax. It typically develops within three days to five weeks after exposure to the drug that causes it.

Nephritis that develops suddenly may cause a change in the amount of urine produced – either an increase or a decrease. When the condition develops gradually, the patient first shows symptoms of kidney failure: nausea, vomiting, decreased appetite, fatigue, and maybe itchiness or difficulty breathing.

Nephritis that follows Zithromax treatment can usually resolve as long as the Zithromax is discontinued. But in more severe cases, kidney function may degrade to the point of renal failure.

Full-on kidney failure can really complicate things. It occurs when the kidneys can no longer adequately filter waste products out of the blood. At the same time, they are also less able to control the amount of water in the body and the levels of electrolytes and acidity in the blood.

Kidney failure can lead to other secondary conditions like high blood pressure, anemia, and abnormally weak bones. If allowed to progress, kidney failure can lead to irreversible damage, possibly requiring dialysis or transplantation.