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Does Fentanyl Cause Bradycardia?

Fentanyl can lead to bradycardia, a condition defined by a slowed heart rate. This medical issue occurs due to fentanyl's negative impact on the central nervous system, as well as the other problems it causes, including an increase in vagal nerve stimulation, degradation of cardiac tissues, and a decrease in catecholamines, which regulate the heart rate.  If caught in time and fentanyl use is stopped, bradycardia can be treated and cured.[1]

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Fentanyl can be a direct cause of bradycardia. This is because, as an opioid, fentanyl targets the opioid receptors in the brain and the central nervous system that regulate the functioning of the heart.[1] 

Whether taken medically or recreationally, there is a risk of fentanyl lowering the heart rate to 40 beats per minute. If unaddressed, this can lead to numerous problems, and most of them are life-threatening.

Does Fentanyl Cause Bradycardia?

Fentanyl is known to cause bradycardia, a slower-than-normal heart rate (between 40 to 60 beats per minute).[1] This means that the heart cannot pump enough blood during any physical activity or even when it is at rest. Someone experiencing bradycardia will experience dizziness, persistent shortness of breath, and loss of consciousness.[2] 

This is a common side effect of fentanyl. In the case of people who are already vulnerable to heart issues, the risk of bradycardia increases with higher doses or rapid administration of fentanyl.[1]

Why Does Fentanyl Cause Bradycardia?

Fentanyl causes bradycardia by binding to opioid receptors in the brain and the central nervous system, which suppresses their control over heart rate. This can bring an otherwise normal heart rate of 60 to 100 BPM down to as low as 40 BPM. Fentanyl attaching itself to major systems, like the vagus nerve, can affect the electrical impulses that control how the heart works.[3] 

Fentanyl’s effects on the cardiac conduction system (the network of nodes, cells, and signals that control the heartbeat) can lead to reduced activity in the sinoatrial node, the small cluster of specialized muscle fibers in the right atrium of the heart. The node is responsible for initiating the process of the heartbeat.[3] 

The Impact of Fentanyl on the Heart

When a person taking fentanyl experiences bradycardia, their heartbeat can become irregular. This is usually an automatic attempt by the heart to overcome the problems caused by the induced irregular heart rate. Additional effects of fentanyl on the heart include the following:[1]


Fentanyl use can increase the risk of arrhythmias, or persistent irregular heart rhythms, again by changing how the brain and central nervous system regulate the operating of the heart.[4]

Myocardial Depression

Another risk of fentanyl consumption is myocardial depression, a condition where the heart’s ability to physically contract and pump blood is hampered. Myocardial depression can affect the entire circulation of blood throughout the body, which can cause hypotension (drastically reduced blood pressure) and, in severe cases, heart failure. 

Increased Risk of Heart Attack & Stroke

Changes to how the heart pumps blood can cause blood to collect inside blood vessels and tissues. If the blood is too sluggish to keep moving, it can clot, increasing the risk of heart attacks and strokes. The more fentanyl is present, the more likely it is that a person using fentanyl will suffer these conditions. 

Respiratory Depression

Fentanyl in the brain can lead to respiratory depression, where oxygen levels in the blood become critically low. If this is not resolved, a condition known as myocardial ischemia can develop, which is where the heart muscle doesn’t receive enough oxygen and nutrients to keep working. This puts undue strain on the heart, which can lead to a heart attack. 


Hypoxia—a condition where insufficient oxygen reaches the body’s tissues, including the heart—can also develop due to the danger of fentanyl-induced respiratory depression. The insufficient oxygen supply can lead to oxidative stress, inflammation, and damage to cardiac tissues, greatly increasing the risk of cardiovascular complications.[5]

Can the Heart Recover?

Whether the heart can recover from fentanyl-related damage depends on the extent and duration of that damage. Even if all damage isn’t reversible, stopping all fentanyl use (and all opioid abuse) can curtail further damage and give the heart the best chance at the fullest recovery possible.

If you or someone you love has been dealing with fentanyl abuse, comprehensive opioid addiction treatment is the best path forward. Through a combination of medication-assisted treatment, behavioral therapy, and complementary approaches, you can stop all opioid abuse and enter a new life in recovery.

Updated March 20, 2024
  1. Cardiac Effects of Opioid Therapy. Chen A, Ashburn M. Pain Medicine. October 2016; Volume 16, Pages S27-S31.
  2. Evaluating and managing bradycardia. Sidhu S, Marine J. Trends in Cardiovascular Medicine. 2020;30(5):265-272.
  3. Fentanyl activates a particular population of vagal efferents which are cardioinhibitory. Inoue K, Samodelov LF, Arndt JO. Naunyn-Schmiedeberg’s Archives of Pharmacology. 1980;312(1):57-61.
  4. Opioid agents and cardiac arrhythmia: A literature review. Azamatov Golibkhon, Akbar B, Muzaffar. Cureus. Published April 23, 2023. Accessed January 24, 2024.
  5. Opioid-induced cardiac arrests are focus of new report. American Heart Association. Published March 8, 2021. Accessed January 24, 2024.
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