The U.S. Food and Drug Administration (FDA) is warning parents to avoid using benzocaine products to reduce teething pain in babies and children under two years of age, unless their use is recommended and supervised by a health professional.
What is benzocaine?
Benzocaine is a local anesthetic found in many over-the-counter (OTC) gels and liquids including Anbesol, Oragel, Baby Oragel, Orabase, and Hurricaine, as well as sprays and lozenges which are popular with adults. Such products have been used for years to relieve gum, mouth, and teething pain. Doctors and dentists often use benzocaine-containing sprays to numb the mucous membranes of the mouth and throat during procedures such as transesophageal echocardiograms, endoscopy, intubation, and feeding tube replacements. However, the use of benzocaine products can lead to a rare, but potentially deadly, condition called methemoglobinemia.
What is methemoglobinemia?
Methemoglobinemia is a blood disorder characterized by the presence of a higher than normal level of methemoglobin (metHb, i.e., ferric[Fe3+] rather than ferrous [Fe2+] haemoglobin) in the blood. Unlike hemoglobin (the molecule in red blood cells that has an increased affinity for oxygen and ability to distribute and release oxygen throughout the body), methemoglobin is an oxidized form of hemoglobin that has a decreased affinity for oxygen and reduced ability to release oxygen to tissues. When methemoglobin concentration is elevated in red blood cells, tissue hypoxia (lack of oxygen in body tissues) can occur. Since methemoglobin cannot bind to and deliver oxygen effectively to body tissues, the amount of oxygen carried through the bloodstream is greatly reduced. Children are at greater risk of methemoglobinemia than adults, and those under two years of age are especially at risk of this condition.
While some forms of methemoglobinemia are inherited or congenital, acquired methemoglobinemia (discussed in this article) is far more common.
Acquired methemoglobinemia may occur after exposure to certain chemicals, drugs, or foods, including:
- Anesthetics such as articaine, benzocaine, and prilocaine
- Benzene
- Certain antibiotics, including dapsone, chloroquine, sulfonamides, and trimethoprim
- Nitrites (used as additives to prevent meat from spoiling)
- Aniline dyes, metoclopramide, chlorates, and bromates
The condition may also occur in infants who are very ill or fed too many vegetables containing nitrates (such as beets).
Symptoms of methemoglobinemia include:
- Pale, gray, or blue-colored skin, lips, and nail beds (cyanosis)
- Shortness of breath
- Fatigue, lack of energy
- Confusion
- Light-headedness
- Headache
- Rapid heart rate
These symptoms can occur within minutes to hours after benzocaine use, and after using the drug for the first time or after several uses.
If you or your child have any of these symptoms after using benzocaine, stop using the product and seek medical help immediately by calling 911, or the local emergency number if outside of the United States.
Call your health care provider if you have a family history of methemoglobinemia and develop symptoms of this disorder.
Conditions which increase your risk for complications from methemoglobinemia include a history of:
- Heart disease
- Smoking
- Breathing problems such as asthma, bronchitis or emphysema.
Treatment and Prognosis:
Methemoglobinemia caused by benzocaine may require treatment with medications and admission to a hospital. Serious cases should be treated immediately. If left untreated or if treatment is delayed, the insufficient amount of oxygen in the blood due to methemoglobinemia may result in shock, seizure, permanent injury to the brain and body tissues, and even death in the most severe cases, according to FDA pharmacist Mary Ghods, R.Ph.
When were warnings about benzocaine first issued?
The FDA first warned of the potential dangers of benzocaine in 2006. Since then, 29 cases of benzocaine gel-related methemoglobinemia have been reported. Nineteen of these cases involved children, with 15 of them in youngsters less than 2 years of age, according to FDA pharmacist Kellie Taylor, Pharm.D., MPH.
The agency repeated the warning in April 2011 due to concern about the continuing use of OTC benzocaine products in children, says Taylor. Parents may have difficulty recognizing the signs and symptoms of methemoglobinemia when using these products at home and often are unaware of the serious potential outcomes. Symptoms may not always be obvious or attributed to the use of a benzocaine product or the onset of methemoglobinemia.
The FDA advises consumers to:
- Store any products containing benzocaine out of the reach of children.
- Use benzocaine gels and liquids sparingly and only when needed. Do not use them more than 4 times a day.
- Read the label to see if benzocaine is an active ingredient when buying OTC products. Labels on OTC products containing benzocaine are not currently required to carry warnings about the risk of methemoglobinemia. If you have any concerns, talk to your health care professional before using them.
To relieve teething pain in a crying baby, the American Academy of Pediatrics offers this advice:
- Give the child a teething ring chilled in the refrigerator.
- Gently rub or massage the child’s gums with your finger.
Contact your health care professional for advice regarding other treatments for gum, mouth, or teething pain.
Always speak with your health care professional before using any product containing benzocaine.
References:
- “Benzocaine and Babies: Not a Good Mix.” U.S. Food and Drug Administration (FDA): Consumer Updates Page. Published 05/31/12. Updated 07/17/12.
- DeBaun, M.R.; Frei-Jones, M.; Vichinsky, E. “Hereditary methemoglobinemia.” In: Kliegman, R.M.; Behrman, R.E.; Jenson, H.B.; Stanton, B.F. Nelson Textbook of Pediatrics. 19th ed. Philadelphia, PA: Saunders Elsevier; 2011: chap 456.7.
- “Methemoglobinemia.” A.D.A.M. Medical Encyclopedia. A.D.A.M., Inc. Review Date: 4/16/2012. Reviewed by: A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, and David R. Eltz. Previously reviewed by Linda Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington School of Medicine; and Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital (8/24/2011).
Comments on this entry are closed.