From the Guidelines
Benzocaine is a local anesthetic that should be used with caution due to the risk of methemoglobinemia, and its use is recommended for temporary pain relief on mucous membranes and skin, with a maximum application of 4 times daily.
Key Points to Consider
- Benzocaine works by blocking nerve signals in the body, specifically by inhibiting sodium channels in nerve cell membranes, which prevents the transmission of pain signals 1.
- It is available over-the-counter in various forms including sprays, gels, lozenges, and creams, typically in concentrations of 5-20% 1.
- The standard application is to apply a small amount to the affected area up to 4 times daily, but not exceeding this frequency to avoid side effects 1.
- Potential allergic reactions and a rare but serious condition called methemoglobinemia, which reduces oxygen in the blood, are possible side effects of benzocaine use 1.
- Benzocaine products should not be used in children under 2 years without medical supervision due to the risk of methemoglobinemia 1.
- Effects typically begin within minutes and last for about 30-60 minutes 1.
- If pain persists beyond a few days or is severe, medical attention should be sought rather than continuing self-treatment 1.
Special Considerations
- Local anesthetic agents, including benzocaine, are cardiac depressants and may cause central nervous system excitation or depression 1.
- The maximum allowable safe dosage of benzocaine should be calculated before administration to avoid excessive doses 1.
- Lower doses should be used in very vascular areas, and the use of epinephrine may enhance the sedative effects of benzocaine 1.
- Topical local anesthetics, including benzocaine, are commonly used and encouraged, but the practitioner should avoid applying excessive doses to mucosal surfaces where systemic uptake and possible toxicity could result 1.
From the FDA Drug Label
Warnings Allergy Alert: do not use this product if you have a history of allergy to local anesthetics such as procaine, butacaine, benzocaine or other "caine" anesthetics Active ingredient Benzocaine 20.0% (w/w)
The use of Benzocaine is as a local anesthetic.
- It is used to numb the area where it is applied.
- The product contains 20.0% (w/w) Benzocaine as the active ingredient 2, 2.
From the Research
Use of Benzocaine as a Local Anesthetic
Benzocaine is commonly used to achieve topical anesthesia of the skin and mucous membranes prior to endoscopic procedures 3. The uses of benzocaine include:
- Topical anesthesia for procedures such as esophagoscopy, bronchoscopy, and endotracheal intubation 4
- Relief of teething pain 5
- Topical anesthesia before invasive procedures such as intubation and transesophageal echocardiogram 5
Risks Associated with Benzocaine Use
The use of benzocaine has been associated with a risk of methemoglobinemia, a condition in which hemoglobin cannot bind and deliver oxygen normally 3, 4, 6, 7, 5. This condition can be potentially fatal if not recognized and treated promptly.
Management of Benzocaine-Induced Methemoglobinemia
Treatment with methylene blue can result in reversal of methemoglobinemia and clinical recovery in most cases 6, 7. It is essential for physicians who perform procedures involving the application of benzocaine for topical anesthesia to rapidly identify and treat methemoglobinemia to avoid significant associated morbidity and mortality 7.