Local anesthesia prevents pain during procedures by blocking nerves from transmitting pain signals to the brain. The effects of local anesthetic are short-lived, so healthcare teams primarily use it for minor outpatient procedures.

Anesthetists or doctors only apply local anesthetic to the part of the body that the medical procedure involves.

People may also receive sedative drugs, which reduce stress levels and promote calmness. Together, anesthesia and sedation enable the doctor or surgeon to carry out the procedure without causing pain or distress.

In cases where surgeons need to perform more invasive or long lasting procedures, anesthetists will typically administer a regional or general anesthetic instead.

Healthcare professionals will consider several factors when determining whether to use local, regional, or general anesthesia. Local anesthesia is generally suitable in the following situations:

  • The procedure is minor and does not require general or regional anesthesia.
  • The procedure is quite quick, and the person will not need to stay overnight.
  • There is no need to relax the muscles or for the person to be unconscious.

Examples of procedures involving local anesthesia include dental surgery, biopsies, and the removal of a verruca, mole, or cataract.

The type and dose of anesthesia will depend on many factors, including the person’s age, weight, allergies, medical conditions, and the site and aim of the procedure.

Healthcare professionals use various drugs to block the pain, which they can deliver in the form of an injection or a spray or ointment.

The drug works by acting on certain nerve pathways to prevent the nerves in the area of application from sending signals to the brain.

It usually takes a few minutes for the drug to take effect, and it wears off after a few hours. A higher dose will last for longer.

Cocaine was the first anesthetic, but its use is now rare. Lidocaine is the most common local anesthetic, but doctors and anesthetists use different drugs for different purposes.

Bupivacaine is more suitable for longer procedures, but it can be more painful than other drugs during administration. Therefore, an anesthetist may use lidocaine first and then inject bupivacaine later if numbness is necessary for a longer period.

Synthetic anesthetics are similar in structure to cocaine, but they do not have the same potential for misuse.

There may be some tingling and pain during the administration of the anesthetic and when it is wearing off, and a person may notice some bruising, but these effects are usually minor.

An individual who has had a local anesthetic should be careful not to injure themselves while they cannot feel pain — for example, by biting their cheek after dental treatment.

Temporary adverse effects that affect some people include:

  • blurred vision, dizziness, and vomiting
  • headaches
  • muscle twitching
  • continuing numbness, weakness, or tingling

Some individuals may also have an allergic reaction and develop hives, itching, and breathing difficulties.

Additionally, cyanosis, where the skin becomes bluish — or grayish in those with darker skin — due to circulation issues or inadequate oxygenation of the blood, can sometimes occur.

An overdose of local anesthetic can also lead to seizures, which can be life threatening.

Local anesthesia is suitable for people undergoing minor surgery.

Examples of minor surgery where local anesthetic is appropriate include:

  • the removal of a tooth
  • a breast lumpectomy
  • carpal tunnel release
  • a discectomy

Examples of major surgery that would likely need general anesthesia include:

  • the removal of a tumor from the bowel
  • a hysterectomy
  • spinal fusion
  • a joint replacement

Doctors consider local anesthesia to be safer than general anesthesia, and it rarely causes serious complications.

The benefits of local anesthesia, compared with general anesthesia, are that:

  • It does not cause a person to lose consciousness.
  • It does not usually need any special preparation.
  • Recovery will be quicker than with general anesthesia.

However, if a person is likely to experience anxiety during a procedure under local anesthesia, a doctor may recommend a sedative to help them stay calm.

Healthcare professionals generally consider local anesthesia to be very safe. For minor surgery, it is safer than general anesthesia.

In very care cases, people may experience serious complications. One of these includes central nervous system depression, where the body’s neurological functions slow down too much, leading to a decreased heart rate and breathing rate. This state can lead to cardiac arrest if the blood stops pumping to the heart.

Some people may also have an allergic reaction, which could lead to hives, swelling, and breathing difficulty. A severe allergic reaction is known as anaphylaxis — a medical emergency that requires urgent medical care.

Another possible complication is seizures. While rare, these are more likely in young children than in adults.

For these reasons, while local anesthesia is generally safe, only a trained professional should administer it.

If a person is going to undergo surgery or another procedure that involves a local anesthetic, the doctor should explain how to prepare for it.

The individual should inform the doctor if they are using any medications, especially blood-thinning agents, such as aspirin or warfarin.

The doctor may instruct the person to refrain from eating during the few hours before surgery. It is also important not to drink any alcohol for 24 hours before receiving the anesthetic.

An individual will often receive local anesthesia in the doctor’s office. Shortly after the doctor applies a local anesthetic agent to the relevant area of the body, it will begin to feel numb.

The doctor will not proceed with the procedure if the person does not feel the numbing effect. While the anesthetic will prevent them from experiencing pain during the procedure, they may still feel pressure.

Depending on the type of procedure and how anxious the person feels, the doctor may also give them a sedative. This medication will help the individual feel calm and less anxious.

The doctor will often place a small device on the person’s finger so that they can monitor the amount of oxygen in the blood. In rare cases, they may use a plastic nasal tube to provide extra oxygen.

Healthcare professionals can also use local anesthesia to help diagnose some chronic conditions and relieve pain after an operation.

Studies have shown that local anesthesia may be more beneficial than opioids, such as morphine, for managing pain after total knee replacement surgery.

An older study from 2010 found that local anesthetics eased some symptoms of inflammatory bowel disease in rats. However, more research is necessary to confirm whether the drugs have this effect in humans.

Local anesthesia prevents pain during minor medical procedures by numbing a specific part of the body. However, a person may still feel some pressure during the procedure.

Anyone administering any type of anesthesia must have received appropriate training and have the necessary qualifications.