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What to Know About Local Anesthesia

Medically Reviewed by Poonam Sachdev on November 09, 2021

‌Local anesthesia numbs a part of your body so that your doctor can stitch up a wound or take a biopsy without you feeling any pain. Unlike general anesthesia, where you are put to sleep during a procedure, you will be conscious during the procedure.‌‌

You can also use local anesthesia for relief from pain caused by cancer and some bone and joint diseases. Local anesthesia drugs help and are safer than opioids. 

How Does Local Anesthesia Work?

‌Your nerves carry pain signals to your brain. Local anesthetic drugs block your nerves and prevent them from carrying these signals. This nerve blockage saves you from feeling pain. 

‌This blockage is temporary. Your nerves will start working in a while. Both movement and feeling will return.

How Do Local and General Anesthesia Differ?

‌Doctors will need you to take general anesthesia for long and extensive procedures. You breathe gas through a mask or get an injection and fall asleep. When you wake up, the surgery is over.

General anesthesia needs expert care. Since you're unconscious, your heartbeat, respiration, oxygenation, and blood pressure must be watched carefully. You may need help in breathing, too.

While you're unconscious, you may vomit and suck the vomited material into your lungs. This can cause aspiration pneumonia, a dangerous condition. For your safety, your doctor will want you to fast for a few hours before anesthesia.

General anesthesia is given to you by an anesthesiologist after your doctor assesses your health in advance. 

Local anesthesia, on the other hand, is simpler. Since you're awake — with only part of your body numbed — it's safer. Side effects like nausea and vomiting are not as common as those after general anesthesia. 

What Are the Advantages of Local Anesthesia?

‌Local anesthesia relieves pain without the risks and preparation of general anesthesia. You're conscious and alert, and only part of your body is numb. It has other benefits too:

  • ‌An anesthesiologist is not needed. Your family doctor or surgeon gives the local anesthesia before starting the procedure.
  • ‌Local anesthesia side effects are uncommon and usually mild.
  • ‌Dangers like aspiration pneumonia are rare. Your procedure won't be delayed because you've eaten recently.
  • ‌You can go home sooner. 
  • ‌Costs are much lower.‌

What Are Types of Local Anesthesia?

‌Local anesthetic drugs are used in three different ways:

Local application. You can apply local anesthetic ointment to open sores or mouth ulcers. Anesthetic eye drops numb the eye for your doctor to remove eyelashes or particles.

Local injection. Your doctor injects a local anesthetic drug under the skin or deeper. You won't feel the needle pricks as your doctor sews a wound. Your doctor also uses such injections to take a biopsy or do a spinal tap to get cerebrospinal fluid (CSF) for testing.

Nerve blocks. Local anesthetic drugs are injected near nerves to block the pain from the area supplied by the nerve. Your doctor uses nerve blocks for dental treatment and eye operations. Spinal anesthesia, used for doing cesarean section, is also a type of nerve block.

Two kinds of local anesthetic drugs are used nowadays. The commonly used drugs are amides like lignocaine, prilocaine, and bupivacaine. The other group is esters like cocaine, procaine, and amethocaine.

How Long Does Local Anesthesia Last?

‌Most often, the effects of local anesthesia wear off quickly. The effect of commonly used local anesthetic drugs, like lignocaine, wears off in about an hour. Your doctor may combine a local anesthetic with other drugs like steroids, clonidine, or epinephrine (adrenaline). This prolongs the anesthesia. 

It's important to take care of the numbed part carefully. After dental treatment, for example, your mouth will be numb, and you might burn yourself by drinking hot coffee. 

When the local anesthesia is needed to work longer, your doctor will use slow-release forms of the drugs or apply continuous infusion of the local anesthetic drugs.

Are There Other Uses of Local Anesthesia?

‌Other than for surgery and other medical procedures, local anesthesia can be used for relief from pain and itching. You can use it for:

  • Open sores, poison ivy contact, and other rashes
  • Cancer-related pain
  • Joint pain — especially in the spine
  • Labor pain — where your doctor may give you an epidural anesthesia
  • Diagnostic processes like biopsy and spinal tap

Are There Side Effects of Local Anesthesia?

‌Local anesthetics are given for local numbing, but it's absorbed into your body and carried by blood all over the body. You may have both local and generalized side effects, including:

  • Soreness at the injection site
  • Tingling feeling
  • Ringing in the ears
  • Headache, dizziness, and confusion
  • Disturbances of the heart rhythm and blood pressure

Show Sources

SOURCES:

‌American Society of Anesthesiologists: "Local Anesthesia."

‌Anesthesia and Analgesia: "Continuous Peripheral Nerve Blocks: An Update of the Published Evidence and Comparison With Novel, Alternative Analgesic Modalities."

Anesthesiology Research and Practice: "New formulations of local anaesthetics-part I."

Journal of Anaesthesiology Clinical Pharmacology: "Topical anesthesia."

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