Understanding the Risks of Incorrect Local Anaesthesia Dosage

Key Takeaways

• Local Anaesthesia is usually safe, but incorrect dosage can cause serious side effects.

• Doctors set dosage based on body weight, age, procedure type, and health conditions.

• Underdose leads to incomplete numbing, while overdose can trigger systemic toxicity.

• Early overdose signs include dizziness, ringing ears, metallic taste, and unusual numbness.

• LOX injection (Lignocaine) is commonly used, and risk increases if dosing limits are exceeded or the medicine enters the bloodstream.

It often begins as a simple medical visit. A dental procedure, a minor cut that needs stitches, or a small skin treatment. You are told it will be painless and quick. Most of the time, it is. The area becomes numb, the work is done, and you leave without any issue.

But sometimes, within minutes of the injection, a patient feels something is off. There may be sudden dizziness, ringing in the ears, or a strange taste in the mouth. Some feel anxious or unusually weak. These reactions can be confusing and scary, especially when no one expects a problem from a “small” injection. This is why understanding local anaesthesia dosage is important for patient safety.

Local anaesthesia is widely used across India and is considered safe when handled correctly. However, it is still a powerful medicine. Incorrect dosing or improper administration can lead to side effects that range from mild discomfort to serious medical emergencies.

What Local Anaesthesia Does In The Body

Local anesthetic blocks the transmission of pain signals from nerves in the area where they are injected. Local anaesthesia does not produce sleep or unconsciousness; you remain awake while the area to be treated becomes numb, allowing the procedure to be completed easily. 

Local anaesthetic has numerous applications, including but not limited to: 

• Dental restorations and tooth removals 

• Sutures on cuts, lacerations, or abrasions 

• Cosmetic and dermatological procedures, such as minor surgery.

• Biopsies and treatment in an outpatient setting 

The local anaesthetic is injected locally; however, it will enter the bloodstream at some point. There are many critical factors, such as technique/dosage, when determining which drug can be safely administered to a patient. 

Why Correct Dosage Is Essential

How safely a person receives a local anaesthetic depends on the dose and how it is administered. The amount of anaesthetic will be determined by how a person's body responds, because chemical anaesthetics "work" in different ways.  

To calculate a proper dosage, a doctor must take into consideration several factors, including:   

• The patient’s body weight/age  

• Length of the procedure and the type of procedure  

• The condition of their liver and heart  

• Whether or not they are pregnant, and  

• Any medications they may currently be taking.   

A dose of local anaesthetic may be considered safe for one person and dangerous for another. Doses that exceed the necessary amount or injections made too quickly increase the risk of the local anaesthetic affecting the brain and heart.

Early Warning Signs To Watch For

The body often gives early signals before serious toxicity develops. These signs usually appear within minutes.

Common warning symptoms include:

• Dizziness or light-headedness

• Ringing in the ears

• Metallic or unusual taste in the mouth

• Numbness around lips or tongue beyond the injection area

• Blurred vision

• Restlessness or sudden anxiety

• Tremors or shaking

These symptoms should never be ignored. Early reporting allows medical teams to act quickly.

Serious Effects If Toxicity Progresses

The rise in blood levels of the medication can lead to increasingly severe symptoms with the potential for urgent medical attention (an emergency).

Although uncommon, these would be classified as emergencies; everyone has quick access to emergency care. Common examples of an emergency due to an increase in the blood levels of medication are:

• Seizures

• Loss of consciousness

• Difficulty breathing

• Sudden drop in blood pressure

• Arrhythmias

Most medical facilities are trained to handle these types of emergencies, but identifying these reactions as emergencies improves treatment outcomes.

Why Dosage Errors Can Occur

Most often, dosage errors result from technical factors rather than negligence. 

Some of the more common examples of technical factors are as follows: 

Multiple injections are administered to the same area that are administered too closely together

• Administering the injection at an equally fast pace

• Incorrectly calculating the dose based on a patient’s weight

• Using an incorrect concentration

• Accidentally injecting into a blood vessel

• Not adequately monitoring after administering the injection

Correct techniques, as well as trained individuals, will greatly reduce these occurrences.

Common Local Anaesthetics Used In Clinics

Many Indian healthcare facilities routinely administer LOX 2% Injection 30ml doses for local anaesthesia during various routine procedures. The active ingredient in LOX Injection is Lignocaine, which prevents the transmission of pain signals from nerves to the brain. 

When used as directed, LOX Injection is both effective and safe; however, if you administer a dose that exceeds the recommended maximum dosage, repeat an injection too rapidly or inject the medicine directly into the bloodstream rather than into the target tissue, problems can occur, and thus even with minimal use, close attention must be paid to carefully determining the patient’s dosage and ensuring that the injection is applied correctly.

Who Is At Higher Risk

Some individuals are more sensitive to local anaesthetic effects and require extra caution.

Higher-risk groups include:

• Children and elderly patients

• People with low body weight

• Patients with liver disease

• Individuals with heart rhythm disorders

• Pregnant women

• Those taking certain heart medications

Providing a complete medical history helps reduce risk.

Final Thoughts

Local anaesthesia is an essential and generally safe part of modern medical care. However, incorrect dosage or improper administration can lead to avoidable complications. Understanding warning signs, knowing personal risk factors, and communicating openly with healthcare providers are key to staying safe. If something feels unusual after a numbing injection, speaking up early can prevent serious outcomes.