Is ingestion of lidocaine (local anesthetic) harmful?

From the Guidelines

Ingesting lidocaine can be dangerous and should be avoided unless specifically prescribed by a healthcare provider in an appropriate oral formulation. Lidocaine is primarily intended for topical use or injection, not for swallowing. Over-the-counter lidocaine products like gels, sprays, and patches are meant for external use only. If accidentally ingested, lidocaine can cause serious side effects including seizures, heart rhythm problems, nervous system toxicity, and in severe cases, even death, as reported in studies such as 1. The severity depends on the amount swallowed, with higher doses being more dangerous. Some prescription lidocaine products are designed for specific oral use, such as viscous lidocaine for mouth sores, but these should only be used as directed by a doctor and not swallowed.

Key Considerations

• Lidocaine toxicity can occur even at therapeutic doses, and patient factors such as low body weight, acid-base status, and hypoxaemia can increase the risk of toxicity, as discussed in 1.
• The correlation of plasma levels with signs and symptoms of toxicity is not linear, making it essential to monitor patients closely when administering intravenous lidocaine, as noted in 1.
• If you or someone else has ingested lidocaine, contact poison control (1-800-222-1222 in the US) or seek emergency medical attention immediately.

Safe Use of Lidocaine

For safe pain relief inside the mouth, ask your healthcare provider about appropriate options rather than using products not designed for ingestion. It is crucial to follow the recommended dosage and administration guidelines for lidocaine, as outlined in studies such as 1, to minimize the risk of toxicity and ensure effective pain management. Always prioritize caution when using lidocaine, and seek medical attention immediately if any symptoms of toxicity occur.

From the FDA Drug Label

Adverse experiences following the administration of lidocaine are similar in nature to those observed with other amide local anesthetic agents. These adverse experiences are, in general, dose-related and may result from high plasma levels caused by excessive dosage or rapid absorption, or may result from a hypersensitivity, idiosyncrasy, or diminished tolerance on the part of the patient Central Nervous System: CNS manifestations are excitatory and/or depressant and may be characterized by lightheadedness, nervousness, apprehension, euphoria, confusion, dizziness, drowsiness, tinnitus, blurred or double vision, vomiting, sensations of heat, cold or numbness, twitching, tremors, convulsions, unconsciousness, respiratory depression and arrest. Cardiovascular System: Cardiovascular manifestations are usually depressant and are characterized by bradycardia, hypotension, and cardiovascular collapse, which may lead to cardiac arrest. Allergic: Allergic reactions are characterized by cutaneous lesions, urticaria, edema or anaphylactoid reactions

Ingesting lidocaine can be harmful. The drug label lists several potential adverse effects of lidocaine, including:

• Central nervous system effects such as confusion, dizziness, and respiratory depression
• Cardiovascular effects such as bradycardia, hypotension, and cardiac arrest
• Allergic reactions such as cutaneous lesions and anaphylactoid reactions These effects can occur due to high plasma levels caused by excessive dosage or rapid absorption, or due to hypersensitivity or idiosyncrasy 2. Additionally, lidocaine is contraindicated in patients with a known history of hypersensitivity to local anesthetics of the amide type 2.

From the Research

Ingestion of Lidocaine

• Ingesting lidocaine can be harmful and even life-threatening due to its potential to cause systemic toxicity 3.
• Lidocaine is a class Ib anti-arrhythmic drug that blocks voltage- and pH-dependent sodium channels, and its use can lead to neurologic manifestations of toxicity, including altered mental status and seizure 3.
• The effects of lidocaine on the human body can be severe, and its ingestion should be avoided unless under medical supervision.

Side Effects and Toxicity

• Lidocaine toxicity can occur even at therapeutic doses, and its early identification and management are crucial to prevent life-threatening complications 3.
• The use of lidocaine can lead to significant adverse effects, including neurologic toxicities, and requires careful monitoring and management 4.
• Lidocaine can also interact with other drugs, which can increase the risk of toxicity and other adverse effects 4.

Medical Use and Administration

• Lidocaine is commonly used as an anti-arrhythmic agent for the treatment of ventricular arrhythmias, and its administration should only be done under medical supervision 5, 6.
• The use of lidocaine for out-of-hospital cardiac arrest patients with shockable rhythms has been studied, and its effects on prognosis and neurological outcome have been compared to other anti-arrhythmic agents, such as amiodarone 6, 7.
• Lidocaine can be effective in managing cardiac arrhythmias, but its use requires careful consideration of the potential risks and benefits, as well as close monitoring for adverse effects 4, 7.