WASHINGTON (AP) -- The Food and Drug Administration is warning consumers about rare chemical burns reported by people using popular pain relief products like Bengay, Icy Hot and Flexall.

The over-the-counter products are designed to provide short-term relief from minor muscle and joint aches and pains. But regulators say they have received reports of skin injuries ranging from first- to third-degree chemical burns caused by the products. Some of burns have required hospitalization, according to a notice posted to FDA's website.

The agency says consumers should stop using the pain relievers if they experience signs of skin injury, such as pain, swelling or blistering of the skin. Doctors should instruct patients on how to use the products, which come in lotions and patches, correctly.