Respiratory depression occurs when breathing becomes too slow or too shallow to keep the body supplied with oxygen and to clear carbon dioxide. It causes hypoventilation, meaning too little air moves in and out of the lungs. It is the reason an overdose of opioids, alcohol, or sedatives can be fatal.
Lung disease, sleep apnea, and conditions affecting the nerves and muscles used for breathing can also impair ventilation or cause respiratory failure, through mechanisms that differ from a drug suppressing the brain’s breathing drive. Because fentanyl and other opioids can cause it, information about fentanyl addiction treatment in South Florida is available for anyone whose opioid use has become hard to control.
What Is Respiratory Depression?
Breathing does two jobs at once. It brings oxygen into the lungs and blood, and it removes carbon dioxide, a waste product of the body’s tissues. MedlinePlus explains that when the blood has too little oxygen or too much carbon dioxide, organs such as the heart and brain can be harmed [1].
With respiratory depression, breathing becomes slower, shallower, or both, and the lungs move less air. Carbon dioxide can build up, and oxygen levels can fall, causing confusion, extreme sleepiness, and in severe cases loss of consciousness. Oxygen levels may remain normal early on, especially when supplemental oxygen is being given.
The drugs that cause it share one feature: they slow the central nervous system. Our guide to what are depressant drugs explains which substances belong to that group and why combining them is so dangerous.
How the Brain Controls Breathing
Breathing is set by respiratory centers in the brainstem, which sense rising carbon dioxide and signal the chest muscles to breathe faster or deeper. These respiratory centers control breathing without any conscious effort, including during sleep. Drugs with respiratory depressant effects weaken that respiratory drive.
The FDA prescribing information for oxycodone explains that the drug causes respiratory depression by acting directly on these brainstem centers, making them less responsive to rising carbon dioxide [2]. The label adds that carbon dioxide build-up from opioid-induced respiratory depression can deepen the drug’s sedating effects. Our post answering are opioids depressants explains how opioids slow the brain and body.
Respiratory Depression Versus Respiratory Failure
Respiratory failure is the condition that results when the blood does not have enough oxygen or has too much carbon dioxide. Respiratory depression is one way to get there, by slowing breathing until gas exchange falls behind.
The oxycodone label warns that respiratory depression that is not recognized and treated right away can lead to respiratory arrest, when breathing stops, and death. That is why slowed breathing from drugs is treated as an emergency.
Other life-threatening complications come from low oxygen levels and high carbon dioxide levels. MedlinePlus notes that people with respiratory failure may become very sleepy, lose consciousness, or develop an irregular heartbeat when the brain and heart are not getting enough oxygen.
What Causes Respiratory Depression?
Drugs can suppress the brain’s breathing drive. Lung disease and nerve or muscle conditions can also impair breathing, and more than one problem can be present at the same time.
Opioids
Opioids are a well-known cause. The oxycodone label warns that serious, life-threatening, or fatal respiratory depression can occur even at recommended doses, with the greatest risk when a person first starts an opioid or after a dose increase.
Potency matters too. The DEA notes that some opioid preparations are so potent that a single dose can be lethal to an inexperienced user, which is part of why fentanyl is so dangerous [3].
Alcohol, Benzodiazepines, and Other Depressants
At toxic levels, alcohol can also suppress breathing. The National Institute on Alcohol Abuse and Alcoholism lists slow breathing of fewer than 8 breaths per minute, or 10 seconds or more between breaths, among the critical signs of an alcohol overdose [4].
Benzodiazepines, sleep medications, and other sedatives add to that slowing. The FDA requires its strongest warning on opioid and benzodiazepine labels because combined use has led to slowed or difficult breathing and deaths [5], and our post on how benzodiazepines differ from opioids explains why each class affects breathing.
Lung Disease and Other Medical Conditions
Inadequate ventilation and respiratory failure are not always caused by drugs. MedlinePlus lists conditions that can lead to breathing failure, including chronic obstructive pulmonary disease (COPD) and other lung diseases, nerve and muscle conditions such as ALS and muscular dystrophy, spinal cord injuries, stroke, and chest injuries.
Sleep apnea is another concern. The oxycodone label notes that opioids can cause sleep-related breathing disorders, including central sleep apnea, and that the risk rises with the opioid dose.
Risk Factors for Respiratory Depression
Some people face a higher risk, especially when medications that slow breathing are involved. Risk factors include:
- Starting an opioid, taking a higher dose, or a recent dose increase
- Combining opioids with alcohol, benzodiazepines, or other sedatives
- COPD, sleep apnea, or other lung or breathing conditions
- Older age, frailty, or serious illness
- Kidney or liver problems that slow the clearance of a drug
- Low tolerance, such as returning to use after a period without opioids
Medicines taken hours earlier can still be active. Our post on how long do benzos stay in your system explains why a benzodiazepine from earlier in the day can still add to the risk.
Signs and Symptoms of Respiratory Depression
Early symptoms of respiratory depression can be subtle, and the person may not notice them. Signs and symptoms to watch for include:
- Slow breathing, very shallow breaths, or long pauses between breaths
- Extreme sleepiness, or being hard or impossible to wake
- Confusion or slurred, slowed responses
- Bluish or gray lips, skin, or fingernails
- Loud snoring or gurgling sounds while asleep
- Pinpoint pupils, a sign of opioid overdose
- Cold, clammy skin and a slow heart rate
MedlinePlus notes that a low oxygen level can cause shortness of breath and a bluish color to the lips and fingernails, while a high carbon dioxide level can cause confusion. Blood pressure can also fall, which our post asking do opioids lower blood pressure explains.
What to Do in an Emergency
Call 911 right away if someone’s breathing is slow, shallow, irregular, or absent, or if they cannot be woken. Follow the dispatcher’s instructions for rescue breathing or CPR. If the person is unconscious but breathing normally, place them on their side in the recovery position and stay with them [6].
Give naloxone if an opioid overdose is possible and it is available. Follow the product instructions for repeat doses; if the person does not respond, another dose may be needed after 2 to 3 minutes. Do not delay rescue breathing or CPR while waiting for it to work. Emergency care is still needed even if the person wakes up, because naloxone can wear off before the opioid does [6].
Respiratory Depression in the Hospital and After Surgery
Opioids are often used for acute pain after surgery or an injury, so healthcare providers watch patients for respiratory depression when prescribing opioids. The oxycodone label advises monitoring for sedation and respiratory depression, especially when starting an opioid or after the opioid dose is raised.
Excessive sedation is an important early warning, even when opioids are given at standard doses. Clinicians check breathing rate and alertness as well as oxygen levels. A pulse oximeter measures oxygen saturation, not ventilation or carbon dioxide, so a normal reading does not rule out dangerous hypoventilation, especially with supplemental oxygen. Clinicians may also use capnography to monitor ventilation [7].
Patients with sleep apnea or COPD may be at high risk. Telling the care team about a sleep apnea diagnosis, and about any breathing machine used at night, such as CPAP or BiPAP (bilevel positive airway pressure), helps them plan pain relief safely.
How Respiratory Depression Is Diagnosed and Treated
To diagnose respiratory depression, healthcare providers check breathing rate, alertness, and oxygen levels, and they listen to the lungs.
MedlinePlus describes common diagnostic tests, including pulse oximetry, a small light sensor on the finger or ear that measures oxygen in the blood, and an arterial blood gas test that measures oxygen and carbon dioxide levels. A chest X-ray can help look for an underlying cause.
Treatment for respiratory depression depends on the cause and how severe it is. Options include oxygen therapy, noninvasive ventilation that uses a mask and air pressure to help air move into and out of the lungs, and in severe cases a ventilator that breathes for the person.
For opioid-induced respiratory depression, naloxone can reverse the effect, and patients are monitored closely afterward. Treating the underlying cause, whether a medical condition or substance use, helps prevent the next episode.
Frequently Asked Questions About Respiratory Depression
What Are the Signs of Respiratory Depression?
The main signs of respiratory depression are slow or shallow breathing, long pauses between breaths, extreme sleepiness, and confusion, while bluish lips or fingernails point to low oxygen. With alcohol, fewer than 8 breaths per minute is a critical warning sign. Anyone who cannot be woken or is breathing very slowly needs emergency care.
Which Drugs Cause Respiratory Depression?
Opioids, including fentanyl, heroin, oxycodone, and morphine, are strongly linked to respiratory depression. Alcohol can too, even drinks with an energizing reputation, as our post on the tequila myth explains. Benzodiazepines, barbiturates, and sleep medications also slow breathing, and combining any of these raises the danger.
Is Respiratory Depression Life-Threatening?
Respiratory depression can be life-threatening because when breathing slows too much, oxygen levels drop and carbon dioxide builds up, which can harm the brain and heart. Without prompt treatment, it can lead to respiratory arrest and death. Call 911 for anyone whose breathing is slow, shallow, or irregular after taking a depressant.
Getting Information and Support
Understanding respiratory depression can help you recognize an emergency and act quickly. If you take opioids or other depressants, ask your doctor or pharmacist whether naloxone makes sense for your household.
The Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-4357 is free and confidential, and anyone in a mental health or suicide crisis can call or text 988. For signs of overdose, call 911. Simple Path Recovery offers medication-assisted treatment in Pompano Beach as part of its outpatient care.
This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Do not stop or change a prescribed medication without talking to your prescriber. If you are in crisis, call or text 988; for signs of overdose, call 911.
Sources
- MedlinePlus, National Library of Medicine. Respiratory Failure. https://medlineplus.gov/respiratoryfailure.html
- U.S. Food and Drug Administration. OXAYDO (oxycodone HCl) Prescribing Information and Medication Guide. Revised April 2024 (Boxed Warning updated December 2023). https://www.fda.gov/media/178921/download
- U.S. Drug Enforcement Administration. Narcotics (Opioids): Drug Fact Sheet. October 2022. https://www.getsmartaboutdrugs.gov/sites/default/files/2022-11/Narcotics%202022%20Drug%20Fact%20Sheet.pdf
- National Institute on Alcohol Abuse and Alcoholism. Understanding the Dangers of Alcohol Overdose. https://www.niaaa.nih.gov/publications/brochures-and-fact-sheets/understanding-dangers-of-alcohol-overdose
- U.S. Food and Drug Administration. New Safety Measures Announced for Opioid Analgesics, Prescription Opioid Cough Products, and Benzodiazepines. August 31, 2016. https://www.fda.gov/drugs/food-and-drug-administration-overdose-prevention-framework/new-safety-measures-announced-opioid-analgesics-prescription-opioid-cough-products-and
- Centers for Disease Control and Prevention, NIOSH. Responding to a Suspected Opioid Overdose. https://www.cdc.gov/niosh/publications/numbered/2019-127.html
- Anesthesia Patient Safety Foundation. Monitoring for Opioid-Induced Respiratory Depression. https://www.apsf.org/article/monitoring-for-opioid-induced-respiratory-depression/
