A French National Centre for Scientific Research (CNRS) researcher holds a test tube rack containing cells to be infected with Covid-19 during coronavirus vaccine research work inside the Pasteur Institute laboratories in Lille, France, March 9, 2020.

Consumers should beware of buying or using products that sellers claim will help diagnose, treat, cure or prevent COVID-19 as the coronavirus continues to sweep across the country, the U.S. Food and Drug Administration said Wednesday.

Some companies are trying to profit from the pandemic by selling unproven and illegally marketed products and falsely claiming they are able to prevent or cure the coronavirus, the FDA said.

"Because COVID-19 has never been seen in humans before, there are currently no vaccines to prevent or drugs to treat" the coronavirus that have been approved by the FDA, the agency said. "These fraudulent products that claim to cure, treat, or prevent COVID-19 haven't been evaluated by the FDA for safety and effectiveness and might be dangerous to you and your family."

Using fraudulent products could cause people to delay or stop appropriate medical treatment and could lead to life-threatening harm, the FDA said.

Fraudulent products range from dietary supplements to COVID-19 tests, drugs, medical devices or vaccines, the FDA said in a statement.

The FDA said it has also seen unauthorized fraudulent test kits sold online. The only way to secure a coronavirus test is through a health-care provider. People could risk unknowingly spreading COVID-19 or not getting treated appropriately if they use an unauthorized test, the FDA said.

The agency also says people shouldn't take any form of chloroquine unless it has been prescribed by a doctor and obtained from legitimate sources.

The FDA sent warning letters to televangelist Jim Bakker and six companies at the beginning of the month for selling unapproved coronavirus drugs and treatment products, including teas, essential oils, tinctures and colloidal silver, which has been cited as not safe or effective for treating any disease, the agency said.