U.S. hospitals have mistakenly treated an unspecified number of patients with an intravenous saline solution that was neither sterile nor meant for use on people, leaving one patient dead and more than 40 others ill, federal health officials said on Wednesday.

Although doctors aren't certain that the unsterilized solution caused the patient's death, other patients were confirmed to have been hospitalized with "adverse effects" such as fever, chills, tremors and headaches, USA Today reported. The unsterilized, "simulated" intravenous fluid had been meant to only be used for training.

Wallcur's simulated IV saline solution, which was shipped to medical clinics, surgical centers and urgent care facilities across several states, have forced the U.S. Food and Drug Administration to issue a safety alert asking providers and pharmacies to refrain from using the Practi-0.9% sodium chloride solution.

"Some patients were hospitalized, and there is one death associated with the use of these products. It is not known if this death is directly related to the use of the product," the FDA said in the safety alert, failing to identify the hospitals.

Since the unsterilized solution had an immediate effect on the patients, health professionals were able to quickly provide medical attention and administer solutions, according to the FDA.

However after learning that "training products" were "not used for their intended purpose," the solution's manufacturer recalled the bags of simulated saline on Jan. 7, according to The Advocate.

"Despite the fact that the products are intended 'for clinical simulation' only, we are aware of reports that these products have been used outside of their intended use and administered to patients," the company said in a statement.

For the past two years, there have been shortages of normal saline solution. In order to alleviate that shortage, the FDA has reportedly allowed companies to import bags of intravenous saline from factories in Europe

Meanwhile, the agency is refraining from releasing any details for now, FDA spokesman Christopher C. Kelly said.

"We will put out additional information when we are able to do so," Kelly said. "Most importantly, we are working to inform health care professionals to carefully check their supply and not inject these products into patients (human and animals)."

Additionally, the case is also being investigated by the Centers for Disease Control and Prevention in seven states, including Florida, Georgia, Idaho, Louisiana, North Carolina, New York and Colorado.

They have already collected samples from the clinics and will be testing them to figure out if the product was responsible for making patients sick.