An Overview of Lidocaine Overdose

Symptoms, Causes, Diagnosis, and Treatment

Show Article Table of Contents

Lidocaine—also known as Xylocaine—is a medication that blocks the transmission of information along the sensory nerves. Sensory nerve cells in the body collect information from organs such as the skin, eyes, and ears. This information is then transmitted to the brain. One type of sensory information is pain.

Blocking these sensory nerves results in numbness and a decrease of pain from areas exposed to lidocaine, which can either be injected into tissues or absorbed through the skin.

Lidocaine is commonly used as a numbing agent during dental procedures and is increasingly being used as a pain reliever in other settings. Lidocaine is especially useful in patients for whom there is a legitimate concern about the potential for abuse of more addictive and mind-altering pain medications.

Unfortunately, the more commonly patients receive lidocaine for pain control, the more likely patients are to experience overdose or adverse reactions. Learn more about the uses and potential dangers of lidocaine, and how overdose is treated.

Symptoms

Lidocaine, which is structurally similar to cocaine, causes both local and systemic effects. Symptoms of lidocaine overdose (also known as lidocaine toxicity) include the following:

  • Numbness (around the mouth or of the tongue)
  • Metallic taste in the mouth
  • Dizziness
  • Ringing of the ears (tinnitus)
  • Blurred vision
  • Restlessness, agitation, or nervousness
  • Paranoia
  • Muscle twitches
  • Seizures

Large overdoses can result in the loss of consciousness. Low blood pressure (hypotension) and slow heart rate (bradycardia) can also occur during local anesthetic overdoses from neural blocks close to the spine.

Accidental injection of lidocaine into the veins during local numbing procedures can lead to severe cardiovascular reactions, including low blood pressure and life-threatening arrhythmias such as atrioventricular heart block, idioventricular rhythms, ventricular tachycardia, and ventricular fibrillation (V-fib).

Causes

Most lidocaine overdoses come from the accidental injection of too much lidocaine during numbing or pain reduction procedures. However, other causes can occur, including the inappropriate use or overuse of lidocaine dermal patches and a combination of lidocaine and cocaine ingestion.

It is very important not to mix lidocaine and cocaine, including the ingestion of cocaine while wearing lidocaine dermal patches.

There is a practice recognized by some physicians of cutting dermal medication patches to reduce the total amount of medication delivered to the patient. Only one type of dermal medication patch reacts predictably to being cut, resulting in a relatively moderate amount of medication delivered from an altered patch.

Depending on the patch, a patient could inadvertently receive significant dosages of transdermal medications, including lidocaine.

Other forms of topical lidocaine, such as creams, can be absorbed at various rates depending on the condition of the skin. When the skin is irritated and inflamed like what happens with burns or laser hair removal, the medicine could absorb much more quickly than expected, causing an overdose.

Diagnosis

The diagnosis of a lidocaine overdose is done primarily through a history and physical exam of the potential patient after the onset of symptoms is recognized. Because of the variability of toxic dosages, the timing of lidocaine administration coupled with the onset of symptoms remains the most common way to diagnose a lidocaine overdose.

There is a blood test that can provide a level for the amount of lidocaine in the blood, but it takes too long for the results to be useful for guiding treatment decisions (which are needed immediately).

Usually, the simple fact of onset of symptoms after administration of the drug is enough to diagnosis a lidocaine overdose. However, sometimes other conditions can mimic the signs of a lidocaine overdose. For instance, an unfortunately timed seizure (due to a seizure disorder or hyperventilation syndrome) can resemble a lidocaine overdose.

Lidocaine overdose from slower-acting administration of the drug, such as dermal patches, is more difficult to diagnose.

In this case, it's very important for the patient experiencing the symptoms to clearly identify the fact that she is wearing a dermal lidocaine patch.

Generally, the prognosis of a lidocaine overdose is positive and most patients will do well to recover.

Treatment

Lidocaine overdose treatment depends on which signs and symptoms the patient is experiencing. If there is a concern about the possibility of seizures, the patient must be treated with medications that provide sedation and seizure control. This is called "raising the seizure threshold." It essentially means that medications are given to make it harder for impulses generated by the nervous system to trigger a seizure.

For patients with cardiac arrhythmias, the patient will often develop cardiac arrest. The patient must be resuscitated using techniques of advanced cardiovascular life support (ACLS), and the expectation is that resuscitation could take much longer than typical.

Patients with suspected lidocaine overdoses should have reduced epinephrine doses of less than 1 microgram per kilogram.

Emergency department treatment of lidocaine overdose requires the infusion of a lipid (fat) emulsion solution. The fat molecules bind to the free lidocaine found in the patient's blood plasma, rendering them ineffective. Lipid emulsion infusions are common for several different types of medication overdoses.

A Word From Verywell

As the use of lidocaine for pain increases, the need for proper treatment of lidocaine overdose will also increase. In most cases, the physician ordering the use of lidocaine will be present when the overdose occurs and can provide treatment immediately. In the event that you might suspect an overdose of lidocaine outside of the presence of a doctor (such as experiencing an overdose from dermal patches), it is best to seek help and explain to the physician that you suspect a lidocaine overdose. These overdoses are usually successfully treated when caught early on.

Was this page helpful?
Article Sources
  • Weaver JM. When can a normal dose be an overdose? Who is at risk?. Anesth Prog. 2014;61(2):45-6. DOI: 10.2344/0003-3006-61.2.45

  • Todd KH. A Review of Current and Emerging Approaches to Pain Management in the Emergency Department. Pain Ther. 2017;6(2):193-202. DOI: 10.1007/s40122-017-0090-5

  • Baron R, Allegri M, Correa-Illanes G, et al. The 5% Lidocaine-Medicated Plaster: Its Inclusion in International Treatment Guidelines for Treating Localized Neuropathic Pain, and Clinical Evidence Supporting its Use. Pain Ther. 2016;5(2):149-169. DOI: 10.1007/s40122-016-0060-3

  • Barat SA, Abdel-Rahman MS. Cocaine and lidocaine in combination are synergistic convulsants. Brain Res. 1996 Dec 2;742(1-2):157-62.

  • Torp KD, Simon LV. Lidocaine Toxicity. [Updated 2018 Oct 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2018 Jan.