(NewsNation) — Several cases of illness related to Botox injections have been reported in Tennessee and Illinois and the Centers for Disease Control and Prevention is currently investigating.

The CDC is warning doctors across the U.S. to be wary of fake Botox injections following the hospitalization of several patients.

Officials in Tennessee and Illinois reported cases of botulism-like illnesses that appeared to be related to Botox injects. The injections were given in a non-medical setting.

Four patients in Tennesee reported symptoms similar to botulism after the cosmetic injections and two were hospitalized. Two patients in Illinois were also hospitalized after being given injections by a licensed nurse who was working outside of her medical authority.

“That’s why it’s important to make sure that you vet the person who’s giving you the Botox. Make sure that it’s a plastic surgeon’s office, or maybe even a dermatologist’s office, and whoever’s administering the shot has done this over and over again,” public health specialist Dr. Saju Mathew told NewsNation.

Officials said they believe counterfeit injections are the source of the illness.

Botulism occurs when a toxin made by Clostridium botulinum attacks the body’s nerves, causing muscle weakness in the face, mouth and throat. Symptoms of botulism include blurred vision, drooping eyelids, slurred speech and trouble swallowing.

While botulism is a dangerous illness, a purified form of the bacteria is approved by the Food and Drug Administration and is used in Botox.

Botox is primarily known for its cosmetic use to reduce wrinkles but the injections also have medical uses. Conditions that can be treated with Botox include muscle spasms, bladder disorders, temporomandibular joint syndrome, migraines and more, with recent research also suggesting it could be used to treat depression.

Public health authorities are warning doctors to be on the lookout for signs of botulism following the reports.