Local anesthetics numb a small area of the body during a procedure while leaving the patient conscious. The anesthesia acts on the membranes of nerve cells, providing relief of pain but keeping the sense of touch and pressure intact. Local anesthetics are common in dentistry and dermatological procedures. The Journal of the American Dental Association (JADA) indicates that local anesthetics have few major side effects when used correctly. However, adverse effects can occur if precautions are not taken.
Prolonged Anesthesia
The duration of action of local anesthetics varies depending on the type of anesthetic used and location of administration. Numbness normally lasts from minutes to several hours; however, in rare cases, it may persist. Prolonged anesthesia resulting from dental treatment can cause a patient to chew or bite her lips or tongue. Although the extended numbness can last days or even months, it usually will disappear without treatment. In extremely rare cases, feelings of numbness will be permanent.
Paresthesia
Paresthesia is a feeling of tingling over the skin. JADA describes this feeling as an altered sensation lasting long after anesthesia has worn off. Practitioners attempt to administer the medication next to the nerve via injection. Paresthesia can result from trauma to the nerve during administration. Although the sensations of paresthesia can be disconcerting, they usually will resolve without treatment within a few months.
Hematoma
Hematoma occurs when blood escapes from blood vessels into the surrounding tissue space. This can occur if the person administering the local anesthetic nicks a blood vessel. Rapid swelling can occur in the area, and a bruise may appear. The swelling lasts approximately seven to 10 days and usually will resolve without treatment. It is imperative that the practitioner take the patient's anatomy into consideration when administering local anesthesia. This assists greatly in preventing hematoma formation.
