The U.S. Food and Drug Administration warned some over-the-counter pain relief creams and gels have "unacceptable" levels of lidocaine.

Lidocaine is a topical anesthetic that prevents pain and is commonly used in cosmetic procedures such as microdermabrasion, laser hair removal, tattooing and piercing.

Six companies were sent warning letters from the FDA, after it discovered the companies' creams and gels contain lidocaine at concentrations that are higher than legally permitted in over-the-counter products, the agency said.

Higher concentrations of lidocaine can lead to irregular heartbeat, seizures, breathing problems, and serious injury if used for prolonged periods of time. It may also interact with other medicines or supplements taken by the consumer.

"These products pose unacceptable risks to consumers and should not be on the market," said Jill Furman, J.D., director of the Office of Compliance in the FDA's Center for Drug Evaluation and Research said in a statement. "We are committed to using all available tools to stop the sale of these illegal high-risk products."

Which Companies Got The FDA's Warning Letters?

The companies that received warning letters and their products are as follows:

TKTX Company: TKTX Numb Maximum Strength Pain Reliever, Mithra+ 10% Lidocaine, TKTX During Procedure Numbing Gel 40% and J-CAIN cream [LIDOCAINE] 29.9%

SeeNext Venture, Ltd.: NumbSkin 5% Lidocaine Numbing Cream (15 grams), NumbSkin 5% Lidocaine Numbing Cream (30 grams) and NumbSkin 10.56% Lidocaine Numbing Cream

Tattoo Numbing Cream Co.: Signature Tattoo Numbing Cream and Miracle Numb Spray

Sky Bank Media, LLC, dba Painless Tattoo Co.: Painless Tattoo Numbing Cream and Painless Tattoo Numbing Spray

Dermal Source, Inc.: New & Improved Blue Gel, Superior Super Juice, Premium Pro Plus, Five-Star Vasocaine and Maximum Zone 1

Indelicare, dba INKEEZE: Ink Eeze Original B Numb Numbing Gel, Ink Eeze B Numb Numbing Spray Black Label and Ink Eeze B Numb Numbing Foam Soap

The companies have 15 days to respond, indicating how they will address the issue, according to the FDA.

The FDA recommends consumers use OTC medications that contain less than 4% lidocaine.