Prolonged Effects of Dental Local Anesthesia: What to Expect

Dental local anesthesia

Hello Doctor: I went to the dentist to get a filling on the upper left side due to a deep cavity, and the doctor administered anesthesia.
I found out that the anesthetic usually wears off in about 3-4 hours.
However, even after more than five hours post-injection, my lips were still numb, and I had difficulty controlling the muscles on the left lower side of my face, making it hard to close my mouth.
After eight hours, it looked more normal, but it still felt a bit strange, and after twelve hours, there was still a slight dullness.
I have previously experienced general anesthesia and laser anesthesia in ophthalmology, and the anesthetics wore off within the normal time frame.
I would like to ask the doctor if it is normal for this type of anesthetic to last twelve hours for me? Is this a sign of a drug allergy? In the future, should I avoid this type of anesthetic altogether, or should I just inform the doctor that I tend to have a prolonged response to it? Thank you.

mo, 20~29 year old female. Ask Date: 2022/11/25

Dr. Huang Baiqing reply Anesthesiology

The commonly used local anesthetics do not typically have such a long duration of action; however, many factors can influence the duration, including the type of local anesthetic, the dosage administered, the method of administration, the injection site, and the condition of the local tissues, all of which can result in varying durations of effect.
Therefore, it is not possible to determine whether the situation you encountered is normal.
Additionally, some physicians may add a small amount of a vasoconstrictor before administration to prolong the duration of the local anesthetic, which is a very common practice in clinical settings.
It is recommended that you inform the physician of the aforementioned situation during your next follow-up appointment.

Reply Date: 2022/11/25

More Info

When it comes to dental procedures, local anesthesia is commonly used to manage pain during treatments such as fillings, extractions, or root canals. However, the duration and effects of local anesthesia can vary significantly among individuals. In your case, experiencing prolonged numbness and difficulty controlling the muscles on one side of your face after receiving local anesthesia raises several important points to consider.

Firstly, it is essential to understand that local anesthetics, such as lidocaine or articaine, typically have a duration of action ranging from 1 to 3 hours, depending on the specific agent used and the method of administration. However, factors such as individual metabolism, the site of injection, and the presence of inflammation or infection can influence how long the anesthetic effects last. In some cases, it is not uncommon for patients to experience residual numbness or altered sensation for several hours beyond the expected duration, especially if the injection was administered near a nerve or if the anesthetic was deposited in a highly vascular area.

In your situation, experiencing numbness for over 12 hours is unusual but not necessarily indicative of an allergic reaction. Allergic reactions to local anesthetics are rare and typically present with symptoms such as hives, swelling, difficulty breathing, or anaphylaxis. The prolonged numbness you are experiencing may be due to the anesthetic affecting the nerve more significantly than usual or possibly due to the technique used during the injection. For instance, if the anesthetic was injected too close to a major nerve, it could lead to extended numbness.

If you have a history of prolonged effects from local anesthesia, it is advisable to communicate this to your dentist or oral surgeon before future procedures. They can take this into account when planning your treatment and may consider using a different anesthetic agent or adjusting the technique to minimize the risk of prolonged numbness. Additionally, if you have any concerns about how your body reacts to anesthetics, discussing these with your healthcare provider can help ensure your safety and comfort during dental procedures.

In terms of managing discomfort or anxiety about future dental work, you might also explore options such as sedation dentistry, which can help alleviate anxiety and discomfort without relying solely on local anesthesia. This could be particularly beneficial if you have had negative experiences with local anesthetics in the past.

In summary, while experiencing prolonged numbness after dental anesthesia can be concerning, it is not always a sign of an allergic reaction. It is crucial to communicate your experiences with your dental provider to tailor your future treatments appropriately. If the numbness persists or is accompanied by other symptoms, seeking further evaluation from a healthcare professional is recommended to rule out any underlying issues.

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