Benzocaine is generally safe for adults when used as directed on intact skin or minor mouth sores, but it carries a rare and serious risk: a blood condition called methemoglobinemia that reduces your blood’s ability to carry oxygen. The FDA has taken action against benzocaine products for infants and young children, and certain adults face elevated risk as well. Whether benzocaine is safe for you depends on your age, how you use it, and a few key health factors.
How Benzocaine Works
Benzocaine is a local anesthetic, meaning it numbs a specific area rather than your whole body. It works by blocking sodium channels on nerve cells, which prevents pain signals from firing. Unlike some related numbing agents, benzocaine acts fast and wears off relatively quickly because it dissociates from nerve cells between pulses of activity. This is why it’s widely used in over-the-counter products for mouth pain, sore throats, and minor skin irritations.
You’ll find benzocaine in familiar brand names like Orajel, Anbesol, Cepacol, Chloraseptic, and HurriCaine. OTC products typically contain 5% to 20% benzocaine for skin and mouth use, and 3% to 7.5% for genital desensitizers.
The Main Risk: Methemoglobinemia
The most serious safety concern with benzocaine is methemoglobinemia, a condition where the iron in your red blood cells gets chemically altered so it can no longer bind and deliver oxygen to your tissues. This can happen even with a single application, though it’s more likely with higher concentrations, repeated use, or application to mucous membranes (like the inside of your mouth or throat).
The FDA estimates more than 400 cases of benzocaine-associated methemoglobinemia have been reported or published in the medical literature since 1971. In an eight-and-a-half-year review period between 2009 and 2017, the agency identified 119 cases. That makes it uncommon relative to the millions of people who use benzocaine products, but the consequences can be fatal.
Signs to watch for include:
- Pale, gray, or blue-colored skin, lips, or nail beds
- Shortness of breath
- Fatigue or confusion
- Headache or lightheadedness
- Rapid heart rate
A late-stage indicator is blood that appears chocolate-brown instead of its normal red. If you notice any of these symptoms after using a benzocaine product, seek emergency medical care immediately.
Children Under 2 Should Not Use It
The FDA has directed that OTC benzocaine oral products should not be used in infants and children younger than 2 years. The agency asked manufacturers to stop marketing benzocaine teething gels entirely for this age group, citing the risk of methemoglobinemia and the fact that these products offer little to no benefit for teething pain in the first place. Prescription lidocaine solutions are also not recommended for teething.
For teething pain in babies, safer options include chilled (not frozen) teething rings, gently rubbing the gums with a clean finger, or giving a cold, wet washcloth to chew on. If your child seems especially uncomfortable, talk to a pediatrician about age-appropriate pain relief rather than reaching for a numbing gel.
Who Else Faces Higher Risk
Beyond young children, several groups have an elevated chance of developing methemoglobinemia from benzocaine. People with glucose-6-phosphate dehydrogenase (G6PD) deficiency, a common inherited enzyme disorder, are particularly vulnerable because their red blood cells are already less equipped to handle oxidative stress. Other hereditary conditions affecting red blood cell function, such as hemoglobin-M disease, also raise the risk.
Lung and breathing conditions like asthma, bronchitis, or emphysema can make the oxygen-reducing effects of methemoglobinemia more dangerous, since your baseline oxygen levels may already be lower. Heart disease adds similar concern. Older adults also appear to be at increased risk, possibly due to reduced enzyme activity that would normally correct the problem on its own.
Broken Skin and Mucous Membranes
Where and how you apply benzocaine matters significantly. Your skin acts as a barrier that limits how much of the drug enters your bloodstream. When that barrier is compromised, through cuts, abrasions, inflammation, or sunburn, absorption increases substantially. Mucous membranes like the inside of the mouth, throat, or genital area are naturally more permeable than intact skin, so benzocaine applied to these surfaces enters the bloodstream faster and in greater quantities.
This is why benzocaine sprays used to numb the mouth and throat before medical procedures are not actually FDA-approved for that purpose. The combination of mucosal application and higher concentrations creates the conditions most associated with methemoglobinemia. If you’re using a benzocaine product on a mouth sore, applying a small amount directly to the sore is safer than coating a large area of your gums or inner cheeks.
Allergic Reactions
Benzocaine belongs to the ester class of local anesthetics, and some people develop contact dermatitis or other allergic reactions to it. Signs include redness, swelling, itching, or a rash at the application site that goes beyond normal irritation. If you’ve had a reaction to other ester-type anesthetics or to products containing para-aminobenzoic acid (PABA, commonly found in some sunscreens), you may be more likely to react to benzocaine as well. An allergic reaction to benzocaine is not the same as methemoglobinemia; it’s a separate immune response, but it’s another reason to stop using the product and consider alternatives.
Using Benzocaine Safely as an Adult
For adults and children 2 years and older without the risk factors listed above, benzocaine products remain available over the counter. The FDA now requires that these products carry warnings about methemoglobinemia on their labels, along with directions stating they should not be used in children under 2.
To minimize your risk, use the lowest concentration that provides relief, apply the smallest amount needed, and avoid reapplying frequently or leaving it on longer than necessary. Don’t use benzocaine on large areas of broken or inflamed skin. If you’re using it for a mouth sore, a single small dab is preferable to generous, repeated applications. Pay attention to any unusual symptoms, especially changes in skin color or breathing, in the minutes and hours after use. Most cases of methemoglobinemia appear within minutes to a couple of hours of application.