Paralyzing Drugs Explained

Paralyzing agents, also described as neuromuscular blocking agents, are powerful muscle relaxants used to prevent muscle movement during surgical procedures or intensive care for severe respiratory disease.

Your anaesthetist will paralyze your intravenous line (IV, vein) before and during your surgery and monitor the effect throughout the procedure.

When these drugs are used during intensive care, they are usually used longer than when they are used during surgery.

Why use paralyzed

Paralyzing agents are used as part of general anesthesia to prevent movement during surgery. General anesthesia involves medicines that make you sleep and prevent pain, such as ketamine, and muscle paralyzing agents that prevent movement.

Because surgery uses sharp instruments and affects delicate parts of the body, even involuntary movements, such as sneezing or minor muscle twitches, can cause serious injury. For this reason, in addition to the muscle movement required for breathing, medical inhibition of muscle movement during surgery is necessary.

intensive care

Neuromuscular blocking agents are sometimes used during intensive care for severe respiratory distress syndrome, when a person needs intubation (insertion of a breathing tube in the throat) due to impaired breathing.

In these cases, muscle paralysis usually lasts 12 to 24 hours or more.

common use

Paralyzing drugs are usually used in the following situations:

  • Put the breathing tube into the trachea
  • abdominal surgery
  • throat surgery
  • some chest surgeries that affect the heart and/or lungs
  • spine surgery
  • brain surgery
  • Many types of orthopaedic (bone) surgery
  • Intensive Care for Respiratory Distress

How numbing drugs work

Paralyzing drugs temporarily interfere with the messages that nerves send to the body’s skeletal muscles. Skeletal muscles are the muscles that control movement of the face, arms, legs, back, and trunk.

The diaphragm muscles that help expand the lungs are also paralyzed by these drugs. With neuromuscular blocking agents, you need mechanical assistance to help you breathe because paralysis of the diaphragm prevents you from breathing on your own. A breathing tube and a ventilator are required to help you breathe.

The paralyzing drug is rapidly distributed throughout the body after injection. They rapidly bind and block neuromuscular binding sites on muscles, preventing them from functioning.

Normally, nerves in the body activate muscles by releasing the neurotransmitter acetylcholine, which binds to and blocks muscle cells. When the neurotransmitter binding site is blocked, the muscle relaxes completely and cannot move until the drug runs out or is reversed medically.

These drugs affect people differently. For example, they may take longer to work in adults over 80, or their actions may last longer for people with kidney or liver disease.

Most commonly used paralysis drugs

Paralyzing drugs are available in hospitals and surgical facilities. Your dose will be carefully chosen before starting, and if you are receiving any of these medicines, you will need to be closely monitored.

Succinylcholine is a fast-acting, short-acting depolarizing muscle relaxant that has traditionally been the drug of choice when rapid muscle relaxation is required.

Common numbing agents used in surgery include:

  • Succinylcholine
  • Rocuronium Bromide
  • Vecuronium Bromide
  • Mitracurium
  • atracurium
  • cisatracurium

After surgery is complete, medication is given to reverse the effects of the paralyzing medication. Examples include acetylcholinesterase inhibitors, neostigmine and iprofen. As with paralyzing drugs, doses must be carefully chosen to avoid negative side effects.

Things paralyzed people don’t do

General anesthesia involves a combination of drugs, monitoring, and support. Paralysis is part of the overall general anesthesia process, and they do not affect pain or memory. Other narcotic drugs provide sedation (put you to sleep) and control pain.

Sedatives used for surgery can also prevent people from remembering the surgery, as well as all aspects of the pre- and post-surgery.

Local anesthesia

Neuromuscular blocking agents are different from local anesthetics that are injected to prevent pain in small areas of the body. Local anesthetics used for surgery may be injected while you are awake – for example during dermatological surgery, certain types of limb surgery, etc.


Neuromuscular blocking drugs are not used at home. Some milder muscle relaxants, such as Flexeril (cyclobenzaprine), can be taken by mouth or injected for problems such as muscle spasms or pain, but they are not as strong as neuromuscular blockers used in surgery.

Paralyzing drug side effects

Even with proper use and careful monitoring, neuromuscular blocking agents can cause side effects.

common side effects

Some common side effects of neuromuscular blocking agents include:

  • muscle twitch
  • heartbeat change
  • shortness of breath or slowed breathing
  • Elevated body temperature
  • blood pressure changes

During the procedure, you will be monitored so that your anaesthetist can detect these side effects quickly. Treatment will begin immediately so your surgery can be done safely.

serious side effects

Serious side effects of neuromuscular blocking agents can include:

  • respiratory arrest
  • heart attack
  • muscle breakdown

Serious complications are more common in people who are at high risk for heart disease, lung disease, obesity or neuromuscular disease. Part of preoperative testing includes identifying potential triggers that may increase the risk of side effects from anesthesia, and possibly adjusting the dose of anesthesia ahead of time to avoid side effects.

After surgery, your healthcare provider will monitor you in the recovery area to see if you experience any side effects when your medicines don’t work. If you experience any side effects, treatment will begin immediately. This may include interventions such as delivering oxygen or medication to your heart or lungs.

Frequently Asked Questions

  • What is a numbing drug?

    A paralyzing drug is a neuromuscular blocker, a powerful muscle relaxant used to prevent muscle movement during surgery or intensive care. Common paralyzing agents include atracurium, cisatracurium, mivacurium, rocuronium, succinylcholine, and vecuronium.

  • How long is the numbing agent used?

    Typically, paralysis drugs are administered during surgery, which can last less than half an hour or as long as several hours, depending on the surgery. If you take paralyzing drugs during intensive care for respiratory problems, you may take them for longer periods of time, such as 12 to 24 hours or more.

  • How long does it take for paralysis to subside?

    Usually, it may take a few minutes to an hour to become active again after the paralytic drugs are stopped or reversed, as these are short-acting drugs. You will be monitored as you recover from all medications under general anesthesia, including sedatives and pain relievers.