What Is Central Nervous System (CNS) Depression?

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What Is Central Nervous System (CNS) Depression?

CNS depression is a form of depression caused by the misuse of CNS depressants. CNS depressants are substances that can slow down your central nervous system. Some common examples include opioids, sedatives, and hypnotics. These drugs are used to treat pain, anxiety, sleep disorders, and stress. Your central nervous system is made up of your brain and spinal cord and controls functions like your blood circulation and digestion. 

CNS depressants work by increasing the activity of a neurotransmitter in your brain, called gamma-aminobutyric acid (GABA). An increase in the activity of GABA in your brain leads to a slowdown of your brain activity. CNS depression is especially common amongst people who use these substances recreationally.

CNS depression varies in severity. You might experience mild CNS depression from the prescribed use of CNS depressants or severe CNS depression from the misuse of CNS depressants, traumatic brain injury, or certain other conditions. 

Symptoms of Central Nervous System (CNS) Depression

People living with CNS depression experience varying symptoms; two people living with the condition might not have the same ones. Some of the most common but mild symptoms that help identify the condition include:

  • Slurred speech
  • Slowed reflexes
  • Higher pain tolerance 
  • Drowsiness 
  • Headaches 
  • Lightheadedness 

In situations where the condition has progressed in severity, a person will experience more severe symptoms, some of which include: 

  • Confusion
  • Extreme fatigue
  • Difficulty breathing 
  • Difficulty staying awake 
  • Fingers and lips that start to turn blue 
  • Low blood pressure 
  • Memory problems


People using central nervous system depressants might sometimes experience mild depression as a side effect. This would typically go away when you stop using the medication or when your body adjusts to the medication.

Before a diagnosis of CNS depression can be made, your doctor will need to examine your medical history and conduct a series of tests. If you have recently been prescribed CNS depressants or abused any CNS depressants, this will be the most likely culprit.

Another major cause of CNS depression in people who have no history of using CNS depressants is a brain injury. If your doctor suspects that a brain injury or tumor is the cause of your depression, they might order a CT scan, an MRI scan, or both. 


The misuse of certain substances causes CNS depression. These substances are referred to as CNS depressants because they affect the activity of your CNS. People either misuse CNS depressants by taking more than prescribed or taking them when they are not prescribed to alter their minds. The most common substances which cause CNS depression include: 

  • Opioids: Opioids are strong pain relievers that are obtained from opiates like heroin and oxycodone. They have a high risk of becoming addictive, which is why they are often prescribed in small doses for only short periods. Opioids are often abused and used recreationally, making them one of the leading causes of CNS depression. Some common types of opioids typically prescribed for severe pain include Vicodin and Percocet. 
  • Alcohol: Although many people don’t think of alcohol as a drug, it’s one of the most common and often abused drugs in the world today. Alcohol abuse can lead to addiction and CNS depression. 
  • Barbiturates: Barbiturates are drugs typically used to treat anxiety and sleep disorders. Some of the most common types include Luminal, Amytal, and Nembutal. Barbiturates are powerful medications, and over time medical professionals have shifted from using them to treat anxiety and sleep disorders to being used as anticonvulsants (anti-seizure medications). 
  • Benzodiazepines: Benzodiazepines, also known as Benzos, are also used to treat anxiety and sleep disorders, although they are considered less addictive than barbiturates. Xanax, Valium, and Prosom are some of the most common types of Benzodiazepines.
  • Sleeping medication: CNS depressants slow down brain activity, making them a great treatment for sleeping disorders. Sonata and Ambien are two types of sleeping medication that are CNS depressants. Although they have a lower risk of dependency than other CNS depressants, long-term use may cause the condition. 

If you or a loved one are struggling with substance use or addiction, contact the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-4357 for information on support and treatment facilities in your area.

For more mental health resources, see our National Helpline Database.

In certain cases, CNS depression could also be caused by a stroke, brain trauma, an aneurysm, or a tumor. Some research shows that even conditions that don’t directly affect the brain, like diabetes or kidney and heart disease, could cause CNS depression. 

Combining one or more CNS depressants often causes CNS depression. Alcohol is typically a culprit in these sorts of situations. This is why these medications specifically prohibit you from drinking alcohol while taking them.

People who already have a history of drug or alcohol dependency are at greater risk of developing severe CNS depression, which is why doctors take a thorough look into your medical history before prescribing CNS depressants for any condition. 


Treatment for CNS depression depends on its cause. If it is a result of the misuse of CNS depressants, certain medications are prescribed.

  • Naloxone: Naloxone is administered to people who are suffering from an opioid overdose. It can either be administered as an injection or given intravenously.
  • Flumazenil: Flumazenil is administered to people who are experiencing severe side effects from using Benzodiazepines. Flumazenil is also used to treat an overdose of medications. However, it’s a short-acting drug and might need to be administered several times before a person recovers.

If severe CNS depression is left untreated, it can be fatal for the person living with the condition. 


Mild CNS depression is typically nothing to worry about. CNS depressants work by slowing down your brain activity, which is why it’s great for conditions like anxiety and sleep disorders. However, if you find that your CNS depressants affect your daily functioning, speak to your doctor about it. They’ll decide if you need to be taken off the medication, switched to another form of the medication, or if your dosage needs to be adjusted. 

However, severe CNS depression needs immediate treatment, or it could result in heart failure or even death. If you are on CNS depressants and suspect it’s making you more lethargic than you should be, don’t stop it until you speak to your doctor. Suddenly stopping the medication could result in more harm than good.

Mild CNS depression is often the goal of taking some CNS depressants, especially sleep and anxiety disorders. It’s important to take the medication exactly as your doctor prescribes to avoid a more severe form of the condition. It would be best to inform your doctor as soon as you experience any side effects that you find intolerable. 

5 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Toketemu Ohwovoriole
Toketemu has been multimedia storyteller for the last four years. Her expertise focuses primarily on mental wellness and women’s health topics.