The health problem has not been previously diagnosed in users of the designer drug, the U.S. Centers for Disease Control and Prevention reported Friday.
The agency said 16 cases of acute kidney injury were reported in six states between March and December 2012.
All of the 16 who received treatment between the ages of 15 and 33, CDC said, and all but one was male.
Some 12 of the patients reported to hospital emergency rooms complaining of pain in their abdomen, side or back. Biopsies performed of six of eight patients found acute tubular injury, while three of eight showed signs of acute interstitial nephritis. Five patients required hemodialysis.
Normal kidney function returned after treatment, the CDC found. However, the agency cautioned that recent studies suggest the illness could lead to an increased risk for chronic and end-stage kidney disease.
CDC said it did not know why the synthetic marijuana caused the illnesses, but suggested it might be associated with a toxin or a new synthetic cannabonoid entering the market.
Rapid heart beat, hypertension, hallucinations and seizures are more commonly associated with synthetic marijuana use.
It is sometimes sold as "synthetic marijuana," "herbal incense," "potpourri" and "spice."
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