An Overview of Lidocaine Overdose

Symptoms, Causes, Diagnosis, and Treatment

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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 a sensory nerve 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 can also be used as a pain reliever in other settings. Lidocaine can be useful in patients who are concerned about using other types of pain medications that may carry the risk of abuse or have mind-altering properties.

Unfortunately, the greater the dosage of lidocaine that is used 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) can 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 in cases of 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

While uncommon, most lidocaine overdoses come from the accidental injection of too much lidocaine during numbing or pain reduction procedures. Iinappropriate use or overuse of lidocaine dermal patches can also result in an overdose. Because of the structural similarity to cocaine, the two can have additive effects and can increase the risk of overdose if used in combination.

It is very important not to mix any forms of lidocaine and cocaine, due to the increased risk of side effects or overdose from their combined effects.

Cutting dermal medication patches to reduce the total amount of medication delivered to the patient does not always have the desired effect. While some types of lidocaine patches may generally be considered safe to cut, there is a risk of altering the release of medication by cutting the patches. Always check with your doctor or pharmacist before cutting any medication patches.

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

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—such as what happens with burns or laser hair removal—the medicine could absorb much more quickly than expected. This, and applying topical lidocaine to a large area of skin, can lead to increased dosage, side effects, and risk of an overdose.

Diagnosis

The diagnosis of a lidocaine overdose is made primarily through a medical history and physical exam of the patient after the onset of symptoms is recognized. The timing and dosage of lidocaine administration coupled with the onset of symptoms is important information that can help during the evaluation.

There is a blood test that can provide a level for the amount of lidocaine in the blood, but it often takes too long for the results to be useful for guiding treatment decisions (which can be 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 person experiencing the symptoms to clearly identify the fact that they are wearing a dermal lidocaine patch.

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.

Patients with cardiac arrhythmias are at risk for cardiac arrest and should be resuscitated using techniques of advanced cardiovascular life support (ACLS), which can take longer than usual in some cases.

Patients with suspected lidocaine overdoses are treated with modified protocols, such as reducing epinephrine doses of less than 1 microgram per kilogram.

Additional treatment of lidocaine overdose can include the infusion of a lipid (fat) emulsion solution. The fat molecules bind to the free lidocaine found in the patient's blood plasma and lower their levels.

A Word From Verywell

As the use of lidocaine for pain increases, the awareness and 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 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.

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