Why Does Fentanyl Cause Chest Wall Rigidity?

Doctors have used fentanyl in medical procedures for years, and since at least 1953, they’ve known that opioids can cause chest wall rigidity.[1] But some people with opioid use disorder (OUD) may not know that the next dose they inject could keep them from breathing properly.

Fentanyl is a powerful opioid, capable of jumping through the brain/blood barrier very quickly and altering how your muscles and nervous system work. Sometimes, that strong opioid causes muscles to tighten, restricting your ability to breathe in and out.

Quick treatment with an opioid antagonist like naloxone can reverse this problem and save your life. But without it, chest wall rigidity can lead to suffocation. 

What Is Chest Wall Rigidity?

Your lungs need space to expand with each inhale and contract with each exhale. People with chest wall rigidity experience very tight muscles along the throat and rib cage, blocking the lung’s normal function.

People with chest wall rigidity often have the following symptoms:[1]

• Tense muscles
• Locked jaw
• Stiff arms and legs
• Episodes of holding their breath

Doctors sometimes call these symptoms wooden chest syndrome, and although rare,  it’s very serious.[2] When your muscles are locked tight, bystanders can’t use CPR to help you breathe. And doctors can’t slip breathing tubes into your throat to help, as your muscles close off the airway.

How Does Fentanyl Cause This Problem?

Researchers aren’t exactly sure why fentanyl causes wooden chest syndrome, but they believe the drug can change important nervous system signals throughout the spinal cord.[2] When the signals change, your muscles tense up all at once. 

While all opioids could cause this problem, fentanyl is especially dangerous. It can cross the blood/brain barrier quickly and interact directly with your nervous system.[1] Injecting the drug worsens the problem.

In studies of healthy people with no history of substance misuse who experienced some degree of rigidity in the larynx after being given fentanyl, symptoms started within about three minutes, and they lasted for about 11 minutes.[3] 

No one can hold their breath successfully for 11 minutes. By the time symptoms ease naturally, you could experience brain damage or lose your life due to your drug use. 

When doctors use fentanyl in medical procedures, they combine it with sedatives to reduce the risk of chest wall rigidity.[2] But people with OUD are not taking their dose under such controlled conditions with medical supervision, so their risks are much higher. 

Researchers say that some people who died due to suspected fentanyl misuse had chest wall rigidity.[3] While many people are aware that fentanyl can cause slowed breathing or heart rhythm problems, they may not be aware that the drug could cause this very severe symptom too. 

Chest wall rigidity is reversible with naloxone, but it must be given promptly. Spraying the drug into the nose is a quick way to reverse an overdose. 

If you think someone may have overdosed on fentanyl, don’t hesitate. Administer naloxone immediately, and call 911.