Find Information About:

Drugs & Supplements

Get information and reviews on prescription drugs, over-the-counter medications, vitamins, and supplements. Search by name or medical condition.

Pill Identifier

Pill Identifier

Having trouble identifying your pills?

Enter the shape, color, or imprint of your prescription or OTC drug. Our pill identification tool will display pictures that you can compare to your pill.

Get Started

My Medicine

Save your medicine, check interactions, sign up for FDA alerts, create family profiles and more.

Get Started

WebMD Health Experts and Community

Talk to health experts and other people like you in WebMD's Communities. It's a safe forum where you can create or participate in support groups and discussions about health topics that interest you.

  • Second Opinion

    Second Opinion

    Read expert perspectives on popular health topics.

  • Community


    Connect with people like you, and get expert guidance on living a healthy life.

Got a health question? Get answers provided by leading organizations, doctors, and experts.

Get Answers

Sign up to receive WebMD's award-winning content delivered to your inbox.

Sign Up

Font Size

Nerve Block for Pain Relief

A nerve block relieves pain by interrupting how pain signals are sent to your brain. It is done by injecting a substance, such as alcohol or phenol, into or around a nerve or into the spine.

Nerve blocks may be used for several purposes, such as:

  • To determine the source of pain.
  • To treat painful conditions.
  • To predict how pain will respond to long-term treatments.
  • For short-term pain relief after some surgeries and other procedures.
  • For anesthesia during some smaller procedures, such as finger surgery.

Nerve blocks are used to treat chronic pain when drugs or other treatments do not control pain or cause bad side effects. A test block is usually performed with local anesthetic. If you achieve good pain relief from the local anesthetic, your doctor may inject a nerve block, such as alcohol or phenol.

What To Expect After Treatment

Nerve blocks numb the nerves touched by the drugs. This relieves pain by interrupting the pain signal sent by the nerves to your brain. Depending on the type of nerve block, your pain may be numbed for a short time or a long time.

Nerve blocks for chronic pain may work for 6 to 12 months. They may have to be repeated.

Why It Is Done

Nerve blocks are used to diagnose the causes of pain. They also are used to treat chronic pain when drugs or other treatments cause bad side effects or do not control pain.

How Well It Works

Nerve blocks often relieve pain. Nerve blocks work well for some types of cancer pain, such as pain from cancer in organs such as the pancreas.1


Nerve blocks can cause serious complications, including paralysis and damage to the arteries that supply blood to the spinal cord. Other possible side effects include severely low blood pressure (hypotension), accidental injection of the alcohol or phenol into an artery, puncture of the lung, damage to the kidneys, diarrhea, and weakness in the legs.

Nerve blocks are not recommended if you have a disease that affects blood clotting, are taking blood-thinning drugs (such as heparin or warfarin), have a bowel obstruction, or have any type of uncontrolled infection.

What To Think About

Doctors can deaden a nerve with a probe that generates intense heat (radiofrequency denervation or ablation) or intense cold (cryoanalgesia).

A nerve block may cause temporary muscle paralysis or a loss of all feeling in the affected area or in the surrounding area.

Complete the special treatment information form (PDF)(What is a PDF document?) to help you understand this treatment.


  1. National Comprehensive Cancer Network (2013). Adult cancer pain. NCCN Clinical Practice Guidelines in Oncology, version 1.2013. Available online:

ByHealthwise Staff
Primary Medical ReviewerE. Gregory Thompson, MD - Internal Medicine
Specialist Medical ReviewerMichael Seth Rabin, MD - Medical Oncology

Current as ofNovember 14, 2014

WebMD Medical Reference from Healthwise

Last Updated: November 14, 2014
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

Today on WebMD

fatigued senior woman
We’ve got 10 tips to show you how
Man snoring in bed
Know your myths from your facts.
Young woman sleeping
What do your dreams say about you?
woman eith hangover
It’s common, and really misunderstood.
Young woman sleeping
Cannot sleep
child sitting in bed
Woman with insomnia
nurse sleeping
Foods That Help Or Harm Your Sleep
Insomnia 20 Tips For Better Sleep
Pain at Night