Why Local Anesthesia Is Used

Local anesthesia is typically used for minor procedures that can be completed in a short time and when a person will be able to return home the same day. Unlike general anesthesia where the entire body is paralyzed and you are unconscious, local anesthesia allows you to remain awake and alert during a procedure. A different type of pain control, regional anesthesia numbs a whole arm, leg, or another region.

Local Anesthesia vs. General Anesthesia

Local anesthesia has many benefits over general anesthesia, but that doesn’t mean one is better than the other. Some of the differences include the following:

Local Anesthesia

• Numbs just a small area of the body to prevent pain
• Given for minor procedures, such as mole removals or root canals
• Commonly given as a single injection, spray, or topical cream
• Breathing muscles are not paralyzed; patient breathes without assistance
• Very low risk of side effects, although they can occur
• Anesthetic effect can last up to eight hours

General Anesthesia

• Paralyzes the whole body and makes the person unconscious
• Given for major procedures, such as open-heart surgery
• Given via a continuous IV infusion, usually into the arm
• An external breathing device is generally necessary
• Higher risk of severe side effects during the procedure and after, but still safe
• Anesthetic effect can last up to 24 hours

Procedures Using Local Anesthesia

Local anesthesia is most commonly associated with minor procedures.

Some examples include: 

• Dental procedures, such as filling a cavity or procedures where the gums must be numbed ;
• Wound suture ;
• Removal of an ingrown toenail ;
• Placement of an IV for a child (to decrease pain in advance of insertion) ;
• Before a biopsy (to numb the skin so a sample can be collected).

How Local Anesthesia Is Given ?

Anesthesiologists are physicians who administer anesthesia and monitor their patients’ breathing, circulation, heart rate, and other vital signs before, during, and after the procedure.

You will likely encounter an anesthesiologist for procedures that require a continuous IV infusion, like an epidural. The anesthesiologist will stay to monitor you throughout the procedure and check on you afterward.

For minor procedures in which vital signs do not need to be continuously monitored, like cavity fillings or mole removals, the doctor who is doing the procedure will usually administer the local anesthesia themselves.

Your local anesthesia may be in the form of a cream, spray, or injection.

Numbing medications are sometimes given in several small injections. A few minutes after the injections have been given, the area should be completely numb. If the area still has sensation, additional injections may be given to ensure it is completely numb.

While the goal is to prevent pain, the anesthesia injection itself can sometimes be painful. That said, pain from the injection will be brief, and the shot will prevent you from feeling pain throughout the rest of the procedure.

Drugs Used for Local Anesthesia

Drugs used as local anesthetics suppress pain receptors known as nociceptors, blocking them from sending pain impulses to your brain.

Some of the most frequently used local anesthetic drugs are:

• Benzocaine
• Lidocaine
• Novocaine
• Tetracaine

Notice how each these ends in -caine. Local anesthetic drugs are related in structure to cocaine, which was widely used as a local anesthetic in the late 19th and early 20th centuries. (It still has some limited use today.) More recent local anesthetics differ from cocaine in that they are not addictive or habit-forming, and they don’t raise blood pressure.

Which drug you may be given and at what dosage depends on your age, height, weight, whether you have any allergies, whether you or your family members have had previous reactions to anesthesia, other medications you are taking, and the length of the procedure.

How Long Local Anesthesia Lasts ?

The length of time a local anesthetic can last depends on which drug was used and how much of the drug was given. Generally speaking, the effects of most local anesthetics begin to gradually wear off within a few hours after the procedure is complete.

Some drugs may take more time to kick in, but their effects may last longer.

• The effects of lidocaine begin within two to five minutes after it is injected and last up to two hours.
• Bupivacaine takes five to 10 minutes to kick in, but its effects can last up to eight hours.
• A synthetic form of the hormone epinephrine is sometimes combined with an anesthetic drug to prolong its effects. Combining lidocaine with epinephrine, for example, extends the effects of lidocaine from two to six hours.

Doctors typically begin by giving you the lowest dose of the drug necessary. If you are having a longer procedure, they may repeat the dose after a certain amount of time has passed to prolong the anesthesia.

For smaller procedures that involve local anesthesia, like mole removals or suturing a small wound, you will be able to go home as soon as the procedure is finished.

There are some cases when you will need to stay longer to be monitored. For example, when a doctor applies a local anesthetic inside your throat to examine your throat and vocal cords (laryngoscopy), you will need to be monitored until your gag reflex returns to ensure it is safe for you to eat or drink.

Anesthetic drugs stop pain receptors from sending pain signals to the brain. Doctors start with the lowest dose necessary and may give additional doses as needed. The effects kick in within minutes and can last from two to eight hours, depending on which drug is used.