The U.S. Food and Drug Administration (FDA) is warning parents that using prescription drugs such viscous lidocaine to treat teething babies could be potentially harmful.

In the past the FDA has recommended that caregivers not use benzocaine products in children under the age of two years unless instructed to by a medical professional, a news release reported. This ingredient can be found in products such as "Anbesol, Hurricaine, Orajel, Baby Orajel, and Orabase."

The oral use of benzocaine gels can lead to a rare but sometimes fatal condition called methemoglobinemia, which affect the amount of oxygen that is carried through the blood stream.

If a child's gums are swollen and tender the FDA recommends massaging them with fingers or giving the child a "cool teething ring or a clean, wet, cool washcloth to chew on." The children should be supervised so they do not choke on the object.

"The cool object acts like a very mild local anesthetic," Hari Cheryl Sachs, M.D., a pediatrician at FDA, said in the news release. "This is a great relief for children for a short time."

Parents have been known to apply viscous lidocaine or other topical anesthetics if their baby is fussing; some even soak their baby's pacifier in it or put it in their formula. This is especially dangerous because the amount of the drug given to the child is not measured in most cases and could be too much.

The drug can also "make swallowing difficult and can increase the risk of choking or breathing in food. It can lead to drug toxicity and affect the heart and nervous system," Michael R. Cohen, RPh, MS, ISMP president, said in the news release.

"Teething is a normal phenomenon; all babies teethe," Ethan Hausman, M.D., a pediatrician and pathologist at FDA, said in the news release. "FDA does not recommend any sort of drug, herbal or homeopathic medication or therapy for teething in children."