Understanding CNS Depression Symptoms and Causes

Are you concerned that you might be experiencing CNS depression from medications or substance use? Read on to learn more about CNS depression and the resulting symptoms.

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Are you feeling drowsy or dizzy after taking a certain medication? You might even feel like your thinking is slowed and that you’re less coordinated than usual. If so, you may be experiencing central nervous system depression, often referred to as CNS depression.

The central nervous system (CNS) is the part of the nervous system that consists of the brain and spinal cord. Some people refer to the central nervous system as the body’s command center, since it controls everything your body does.  

Many medications can cause CNS depression, and when you take multiple central nervous system depressants at the same time, your risk of experiencing CNS depression symptoms increases. Read on to learn more about what CNS depression is, CNS depression symptoms, and more.

What is CNS depression?

Simply put, CNS depression is when central nervous system activity slows down. But what exactly does that mean?

“It’s a slowing of the activity within the brain and spinal cord that reduces alertness, breathing, and baseline activity,” says Rebecca Holland, a Psychiatric Mental Health Nurse Practitioner with Charlie Health. It often occurs due to someone taking a central nervous system depressant — a medication or substance that slows brain activity and suppresses nervous system function.

CNS depression signs and symptoms 

CNS depression symptoms range from mild to severe and even life-threatening. Holland says the most common and mild CNS depression symptoms are:

• Drowsiness
• Slowed thinking
• Dizziness
• Reduced coordination

Generally, these are the side effects that your prescriber might warn you about when prescribing you a medication that falls under the CNS depressant medication umbrella. These mild symptoms are not necessarily red flags, especially when a medication is taken as prescribed and monitored, but they should still be taken seriously.

However, it’s possible for CNS depression symptoms to progress into much more dangerous territory. According to Holland, severe CNS depression symptoms are confusion, inability to stay awake, very slow breathing, and unconsciousness.

These symptoms are  more likely to happen with higher doses, mixing substances (such as taking two CNS depressants together, or taking one CNS depressant medication while drinking alcohol), and underlying health conditions. “[Contact your provider] if sedation interferes with daily functioning, breathing seems slowed, or there is concern for overdose,” Holland says. If there’s concern about an overdose, call 911. 

CNS and respiratory depression symptoms

Respiratory depression is a dangerous complication of central nervous system depression. It refers to slow, shallow, ineffective breathing. Ultimately, this leads to a buildup of carbon dioxide (CO2) in your blood. This CO2 buildup may also prevent oxygen from getting into your lungs. 

There are more symptoms than just slow and labored breathing. If you’re experiencing respiratory depression, you might also have these symptoms:

• Confusion
• Fatigue
• Dizziness
• Headache
• Nausea and vomiting
• Rapid heartbeat
• Blue-tinted lips, skin, or nails

If you’re experiencing symptoms of severe respiratory depression, seek medical attention immediately. Severe respiratory depression can lead to respiratory failure and even death.

Causes of CNS depression   

There are many causes of CNS depression, ranging from antianxiety medications to opioids to alcohol. Many medications can cause CNS depression, including

1. Benzodiazepines

These are sedatives, most commonly prescribed for panic attacks and severe anxiety disorders. Examples are Xanax (alprazolam), Klonopin (clonazepam), Ativan (lorazepam), and Valium (diazepam)

2. Opioids

Opioids, both legal and illicit, can cause CNS depression. Examples are oxycodone, hydrocodone, morphine, fentanyl, heroin, and codeine.

3. Sedative-hypnotics

These sedatives are typically used for insomnia treatment. Popular examples include Ambien (zolpidem) and Lunesta (eszopiclone).

4. Barbiturates

Drugs in this class may be used as sleep aids, headache relief, or to treat a seizure disorder. Examples include Butalbital (often in migraine/headache medications), and Phenobarbital and Primidone, used for seizures. 

5. Alpha-2 adrenergic agonists

These medications are sometimes prescribed for hypertension (high blood pressure), ADHD, or anxiety-related symptoms. Examples include clonidine (used for hypertension, anxiety, or ADHD) and guanfacine (used for ADHD).

6. Anticonvulsants

These are anti-seizure medications, but they are also used to treat some mental health conditions. Examples are Depakote (valproic acid) and Lamictal (lamotrigine), which can treat both epilepsy and bipolar disorder.

7. Antipsychotics

Antipsychotics are used to treat conditions such as schizophrenia, mania in bipolar disorder, and severe major depressive disorder. Examples include haloperidol, which can treat hallucinations and delusions in schizophrenia, and risperidone and aripiprazole, which can treat mania in bipolar disorder.

8. Antihistamines

First-generation antihistamines (typically allergy medications) can cross the blood-brain barrier and affect the central nervous system — even over-the-counter ones. Examples include Benadryl (diphenhydramine) and hydroxyzine, which is also used to treat anxiety.

9. Muscle relaxants

Muscle relaxants act on both the peripheral nervous system and the central nervous system. They’re prescribed for muscle spasms or muscular pain. Examples are Flexeril (cyclobenzaprine) and Skelaxin (metaxalone).

It’s important to take these medications exactly as your provider instructs you to. Do not take it more frequently or in higher doses, as this can lead to an increased risk of serious CNS depression symptoms. Additionally, you should not abruptly stop taking a prescribed CNS depressant medication unless your provider explicitly tells you to do so. Stopping abruptly, especially when you’ve been taking a medication for a while, can lead to withdrawal symptoms.  

Although not a medication, it’s important to note that alcohol is a CNS depressant, too. It slows brain activity, which is why drinking alcohol can slow down reaction time, stop you from thinking clearly, and affect your coordination. Mixing alcohol with any central nervous system depressant leads to increased risk for potentially dangerous and severe symptoms of CNS depression, including respiratory depression.

Additionally, some health conditions may result in central nervous system depression, including:

• Traumatic brain injury (TBI)
• Severe infections (such as meningitis or encephalitis)
• Stroke

What is long-term CNS depression?

Long-term CNS depression refers to ongoing or repeated suppression of central nervous system activity over time, rather than a short-term or situational episode of CNS depression.

What are the causes of long-term CNS depression?

“[Causes include] chronic use of sedating substances or medications, or repeatedly combining them,” Holland says. For example, this could occur from prolonged use of benzodiazepines or opioids. It could also be a result of alcohol use disorder or substance use disorder (abusing opioids).

What are the symptoms of long-term CNS depression?

Persistent fatigue, slowed cognition, memory issues, and reduced coordination are common symptoms of long-term CNS depression, Holland says. If you believe you’re experiencing long-term CNS depression, it’s important to bring it up to your healthcare provider. 

How Charlie Health can help

Are you or a loved one struggling with mental health? If so, Charlie Health can help. Charlie Health’s virtual Intensive Outpatient Program (IOP) provides more than once-weekly mental health treatment for dealing with serious mental health conditions.

Our expert clinicians incorporate evidence-based therapies into individual counseling, family therapy, and group sessions. We also provide medication management when necessary. With treatment and support, healing is possible. Fill out the form below or give us a call to start healing today.