What are over-the-counter (OTC) topical anesthetic creams?

From the Guidelines

Over-the-counter numbing creams should be used with caution, prioritizing lidocaine or benzocaine for minor pain relief, as they are generally effective and safe when used as directed, according to the most recent evidence 1. When considering the use of OTC numbing creams, it is essential to weigh the benefits and risks. The active ingredients in these creams, such as lidocaine, benzocaine, or prilocaine, work by temporarily blocking nerve signals in the applied area, preventing pain sensation from reaching the brain. Some key points to consider when using OTC numbing creams include:

• Apply a thin layer to the affected area up to 3-4 times daily
• Avoid using on broken skin or covering large body areas
• Most OTC options contain between 4-5% lidocaine, which provides temporary relief for conditions like minor burns, insect bites, or muscle aches
• Benzocaine products (like Orajel at 20%) work well for oral pain but carry a small risk of methemoglobinemia, especially in young children
• Effects typically last 1-2 hours
• Don't use these products for more than 7 consecutive days without medical consultation, as prolonged use can cause skin irritation or, rarely, systemic absorption issues
• Always wash hands after application and keep away from eyes, nose, and mouth It is also important to note that topical anesthetics can be effective in reducing pain from some procedures, such as venipuncture, lumbar puncture, and intravenous catheter insertion, in term and preterm neonates, as shown in a study published in Pediatrics 1. However, the risks of methemoglobinemia associated with the use of topical lidocaine-prilocaine cream can be minimized if used no more than once daily, on intact skin only, and not with other drugs known to cause methemoglobinemia. In terms of specific recommendations, lidocaine creams (like Aspercreme with 4% lidocaine) are generally effective and safe when used as directed, making them a suitable option for minor pain relief. Ultimately, the decision to use OTC numbing creams should be made with caution, taking into account the potential benefits and risks, and prioritizing the use of lidocaine or benzocaine for minor pain relief.

From the FDA Drug Label

PRINCIPAL DISPLAY PANEL - 77 g Bottle Carton TopCare® health COMPARE TO ICY HOT® ACTIVE INGREDIENTS* MAXIMUM STRENGTH LIDOCAINE Cold & Hot Pain Relieving Lidocaine Cream 4% Lidocaine • 1% Menthol LIDOCAINE 4% / TOPICAL ANALGESIC MENTHOL 1% / TOPICAL ANALGESIC Helps to Numb Away Pain Non-Greasy Maximum Strength External Analgesic with 4% Lidocaine 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

• OTC numbing creams contain ingredients like Lidocaine 4% 2 and Benzocaine 3
• These creams are used for topical analgesic purposes, helping to numb away pain
• Key warnings include avoiding contact with eyes, not exceeding recommended dosage, and not using for more than 7 days unless directed by a dentist or doctor 3

From the Research

OTC Numbing Creams and Methemoglobinemia

• OTC numbing creams, such as those containing benzocaine and lidocaine, can cause methemoglobinemia, a rare but potentially fatal condition characterized by abnormal levels of oxidized hemoglobin that cannot bind to and transport oxygen 4, 5, 6, 7, 8.
• Methemoglobinemia can occur after topical application of these creams, and symptoms may include central cyanosis, low oxygen saturation, and respiratory failure 4, 6, 7, 8.
• The metabolites of benzocaine and lidocaine, such as benzocaine hydroxylamine and 4-hydroxyxylidine, have been shown to produce methemoglobin in whole human blood in vitro 5.
• Treatment of methemoglobinemia typically involves administration of methylene blue and supplemental oxygen, and in some cases, ascorbic acid may be used to treat associated hemolysis 6, 7, 8.

Risk Factors and Prevention

• Patients using OTC numbing creams containing benzocaine and lidocaine should be aware of the risk of methemoglobinemia and monitor for symptoms such as cyanosis, dizziness, and headache 7.
• Early diagnosis and treatment of methemoglobinemia are crucial to prevent long-term complications and improve clinical outcomes 8.
• Physicians should be aware of the potential for methemoglobinemia in patients using these creams, especially in cases where patients have underlying medical conditions or are taking other medications that may increase the risk of this condition 4, 6.