Some pain-relieving skin products contain potentially harmful doses of the numbing agent lidocaine and should be avoided, the U.S. Food and Drug Administration warns.

These creams, gels, sprays and soaps are marketed for topical use to relieve the pain of cosmetic procedures like microdermabrasion, laser hair removal, tattooing and piercing, the FDA said.

The agency has issued warning letters to six companies that are marketing products containing concentrations of lidocaine heavy enough to harm people, particularly after cosmetic procedures that could cause the cream to be absorbed more readily through the skin.

Products containing lidocaine over 4% can contribute to health problems like an irregular heartbeat, seizures and breathing difficulties, the FDA explained. They also can interact with other medications or supplements a person is taking.

“These products pose unacceptable risks to consumers and should not be on the market,” Jill Furman, director of the Office of Compliance in the FDA’s Center for Drug Evaluation and Research, said in an agency news release. “We are committed to using all available tools to stop the sale of these illegal high-risk products.”

The companies and products covered by the warning letters include:

• 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, doing business as 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, doing business as 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 FDA is particularly concerned if these products are applied over large areas of skin for prolonged periods of time, especially if the skin is irritated or broken.

Consumers also should not wrap skin treated with any over-the-counter pain relief products with plastic wrap or other dressings, which can increase the risk of side effects, the FDA said.