Can Steroids Cause Atrial Fibrillation?

Steroids can cause atrial fibrillation, and the evidence is strong enough that clinicians consider it a recognized side effect. A large meta-analysis pooling data from over 679,000 people found that corticosteroid use raised the risk of atrial fibrillation by about 74 percent overall, with the risk climbing higher at larger doses and longer durations of use. But the relationship between steroids and this common heart rhythm disorder is more layered than a simple yes-or-no, because the type of steroid, the dose, the route it enters your body, and even the clinical setting can shift the picture dramatically.

Corticosteroids and Atrial Fibrillation Risk

When most people hear “steroids” in a medical context, they are thinking of corticosteroids like prednisone, dexamethasone, or methylprednisolone, the anti-inflammatory drugs prescribed for conditions ranging from asthma flare-ups to autoimmune disease. These are the steroids with the clearest link to atrial fibrillation. A case-control study using a large Dutch pharmacy database found that people who filled a corticosteroid prescription within the previous month had roughly four times the odds of developing new-onset atrial fibrillation compared with nonusers. That elevated risk held up regardless of whether the steroid was prescribed for lung disease, rheumatic conditions, allergies, or blood cancers, suggesting the drug itself was the problem rather than the underlying illness driving it.¹

A separate population-level study found a similar pattern with oral corticosteroids, reporting roughly two-and-a-half times the risk of atrial fibrillation, particularly at the start of therapy. Users of inhaled steroids, by contrast, showed no meaningful increase in arrhythmia risk overall.² That distinction between oral and inhaled steroids is important for the millions of people using daily inhalers for asthma or COPD, who can generally be reassured that their inhaler is not a major atrial fibrillation trigger on its own.

Dose Makes the Difference

Across the research, one pattern stands out consistently: higher doses of corticosteroids carry a much larger risk than lower ones. In the Dutch study, high-dose use was linked to about a sixfold increase in odds of new-onset atrial fibrillation, while low-to-intermediate doses showed no statistically significant risk at all.¹ The 2025 meta-analysis reinforced this dose-response relationship across a broader body of evidence, finding that higher doses and longer treatment courses both pushed the risk upward.³

The route of administration also matters. Intravenous corticosteroids, the kind given in hospital settings for severe flare-ups, roughly doubled the risk of atrial fibrillation. Oral corticosteroids were close behind at about 1.95 times the risk. Inhaled corticosteroids carried the smallest increase, at around 1.67 times, though even that is worth noting for people already at elevated cardiac risk.³ That said, the earlier population study found no excess arrhythmia risk from inhaled steroids, so the picture for inhalers specifically may depend on the patient population and how “risk” is measured. The safest interpretation is that inhaled steroids are far lower risk than oral or IV but not necessarily zero risk for everyone.

Timing adds another wrinkle. The risk appears highest in the early days and weeks of a new steroid course. The population study of respiratory medications found that short-term oral steroid use carried a higher relative risk for atrial fibrillation than ongoing use, with the first days of treatment being the riskiest window.² If you have been prescribed a short burst of prednisone for a severe allergic reaction or asthma attack, this early-risk window is worth knowing about, especially if you already have risk factors for abnormal heart rhythms.

How Corticosteroids Trigger Abnormal Rhythms

The heart’s normal rhythm depends on a coordinated flow of electrical signals through the atria. Corticosteroids can interfere with that coordination through several pathways working in parallel.

One well-understood route involves potassium. Corticosteroids promote potassium loss through the kidneys by activating mineralocorticoid receptors that increase sodium reabsorption and push potassium out. When blood potassium drops too low, the electrical stability of heart cells deteriorates, making arrhythmias more likely.⁴ This electrolyte disturbance can happen surprisingly quickly at high doses and is one reason doctors often monitor potassium levels during aggressive steroid therapy.

Beyond the acute electrolyte effect, corticosteroids can drive structural changes in the heart. They promote high blood pressure, elevate blood sugar, and encourage fluid retention, all of which strain the atria over time. At the cellular level, corticosteroids can trigger remodeling of heart muscle cells, including promoting fibrosis (scarring), inflammation within atrial tissue, and changes to ion channels that govern the heart’s electrical rhythm.³ This remodeling can create patches where electrical signals slow down or loop back on themselves, exactly the conditions that allow fibrillation to take hold.

Anabolic Steroids Are a Separate but Real Risk

The conversation around steroids and atrial fibrillation often focuses on prescription corticosteroids, but anabolic-androgenic steroids, the kind used for muscle building, carry their own cardiac risks. A large registry study following over 1,100 anabolic steroid users for an average of 11 years found that they had more than double the rate of arrhythmias compared with matched controls, alongside dramatically higher rates of heart attack, heart failure, and cardiomyopathy.⁵

The mechanisms differ from those of corticosteroids. Anabolic steroids enlarge the heart, particularly the left ventricle, and promote fibrosis and inflammation in atrial tissue through androgen-receptor-mediated pathways. Research using a derivative of testosterone found that it increased the expression of genes linked to fibrosis, inflammation, and abnormal thickening in atrial tissue.⁶ Separately, a study of bodybuilders found that long-term anabolic steroid users had significantly longer atrial electrical delays compared to nonusers, a measurable precursor to atrial fibrillation. The delay between atrial chambers was roughly double that of the control group.⁷

Case reports add another dimension. In one published case of a young man who developed atrial fibrillation while using anabolic steroids, the arrhythmia resolved after he stopped taking them and had not recurred ten weeks later.⁸ A more recent case report described a similar scenario in an otherwise healthy individual, noting that the absence of other identifiable triggers and the resolution of symptoms upon stopping steroids strongly suggested a direct causal link.⁹ These individual cases are not proof on their own, but stacked alongside the population data and the measured electrical changes in bodybuilders, the pattern is convincing enough to take seriously.

The Cardiac Surgery Paradox

Here is where the steroid-and-AF story takes an unexpected turn. Despite all the evidence that corticosteroids can trigger atrial fibrillation in medical patients, giving steroids around the time of heart surgery actually appears to prevent it. Atrial fibrillation after cardiac surgery is extremely common, occurring in roughly a quarter to half of patients depending on the procedure. A meta-analysis of randomized controlled trials found that prophylactic corticosteroid therapy reduced the incidence of post-operative atrial fibrillation by about 30 percent.¹⁰

In one of the individual trials contributing to that analysis, atrial fibrillation developed in 21 percent of patients who received steroids before coronary artery bypass surgery versus 51 percent of those who received a placebo. That is a substantial difference.¹¹

The explanation is not as contradictory as it first appears. Post-surgical atrial fibrillation is largely driven by acute inflammation from the surgical trauma itself, the cardiopulmonary bypass, and the body’s healing response. In that specific context, the powerful anti-inflammatory action of corticosteroids outweighs their pro-arrhythmic tendencies. You are trading one mechanism for another, and the net effect is fewer episodes of fibrillation. This does not mean that steroids are “safe for the heart” in general; it means the surgical context is unique enough to flip the balance. Outside of cardiac surgery, the same anti-inflammatory properties do not override the other pathways through which steroids disrupt heart rhythm.

The Role of the Body’s Own Steroids

Your body produces its own steroids that matter for atrial fibrillation risk, and this line of research helps explain why some people develop AF even without taking any steroid medication. Two hormones stand out: cortisol and aldosterone.

Cortisol, the body’s main stress hormone, is itself a corticosteroid. Patients with Cushing’s syndrome, a condition of chronic cortisol excess, have high rates of cardiac arrhythmias. A genetic study used inherited variations that predict higher cortisol levels to test whether the association is causal. Each standard-deviation increase in genetically predicted cortisol was associated with a 20 percent higher risk of atrial fibrillation. However, that risk appeared to work through cortisol’s effects on blood pressure and waist circumference rather than through a direct electrical effect on the heart, because the association disappeared after adjusting for those intermediaries.¹² In practical terms, this means that chronic stress, sleep deprivation, and other states that keep cortisol elevated contribute to AF partly by raising blood pressure and promoting abdominal weight gain over time.

Aldosterone, a mineralocorticoid hormone that regulates salt and water balance, has an even more direct connection. Aldosterone activates receptors in the heart that promote fibrosis, inflammation, and dysfunction of heart muscle cells, all of which set the stage for fibrillation.¹³ Research on atrial tissue from patients with AF found that left atrial fibrosis was four times worse than in patients with normal rhythm, and that blocking the mineralocorticoid receptor with drugs like spironolactone could prevent these fibrotic changes in laboratory models.¹⁴ This is why some cardiologists are interested in mineralocorticoid receptor blockers as a potential tool for preventing AF progression, though that remains an area of active investigation rather than standard practice.

Inflammation, Steroids, and the Chicken-or-Egg Problem

One of the trickiest aspects of studying steroids and atrial fibrillation is untangling the drug from the disease. People who take corticosteroids often have serious inflammatory conditions, and inflammation itself is a risk factor for atrial fibrillation. Atrial fibrosis, the scarring that disrupts electrical conduction, can be directly caused by chronic inflammation. Research on anti-inflammatory drug use and AF risk has argued that the drugs might sometimes be a proxy for the inflammatory condition rather than the direct cause of the arrhythmia.¹⁵

However, the Dutch case-control study addressed this by looking at AF risk across very different indications for steroid use. The fact that risk was elevated regardless of the underlying condition, whether it was asthma, arthritis, or a blood cancer, argues against the illness itself being the full explanation.¹ The reality is probably a combination: the drug adds risk on top of whatever risk the underlying disease already carries. If you have rheumatoid arthritis, for instance, the inflammation from the disease and the corticosteroid used to treat it may both be pushing your heart rhythm in the wrong direction.

What This Means If You Take Steroids and Blood Thinners

For people who already have atrial fibrillation and take blood thinners to prevent stroke, adding a corticosteroid creates a practical safety concern beyond the rhythm itself. A nationwide cohort study found that among patients taking newer oral blood thinners for AF, concurrent corticosteroid use was associated with about a 53 percent higher risk of bleeding events, including a roughly 49 percent increase in the risk of bleeding inside the skull.¹⁶ Corticosteroids ranked among the highest-risk co-medications for bleeding in that study, comparable to certain anti-platelet drugs. This does not mean you should stop either medication without guidance, but it does mean the combination deserves close monitoring and an honest conversation with your prescriber about whether the steroid course is necessary and how long it needs to last.

Practical Points for People on Steroids

If you are starting a new corticosteroid course and already have known heart disease or risk factors for atrial fibrillation (older age, high blood pressure, obesity, sleep apnea, heavy alcohol use), the first few days of treatment are the riskiest window for a new arrhythmia. Symptoms to watch for include a sudden fluttering or racing sensation in your chest, feeling unusually short of breath, dizziness, or lightheadedness. Atrial fibrillation sometimes causes no symptoms at all, which is part of what makes it tricky.

Low-to-moderate steroid doses appear far safer than high-dose pulses, at least in terms of AF risk. If your doctor has clinical flexibility in dosing, this is worth discussing. Short courses at high doses, which are common for acute flare-ups, appear to carry more initial arrhythmia risk than slow tapers, though the total accumulated risk increases with longer treatment durations as well.

For people using anabolic steroids outside of medical supervision, the cardiovascular risks extend well beyond atrial fibrillation. The population data show dramatically elevated rates of heart attack, heart failure, and cardiomyopathy alongside arrhythmias. The encouraging part of the case-report evidence is that atrial fibrillation in younger anabolic steroid users has sometimes resolved after stopping the drugs, but structural damage to the heart from long-term use may not reverse so neatly. The electrical delays measured in bodybuilders who were active users suggest that the atrial substrate for fibrillation builds up over time, even when the person feels perfectly fine.

People using inhaled corticosteroids for asthma or COPD have the least to worry about. The population-level evidence is reassuring that standard inhaler doses do not meaningfully increase arrhythmia risk, though the meta-analysis did detect a small statistical increase. If you are using an inhaler as directed and have no other cardiac risk factors, the risk from uncontrolled lung disease almost certainly outweighs any theoretical arrhythmia risk from the inhaler.

Mineralocorticoid Receptor Blockers and Future Directions

Because aldosterone-driven fibrosis plays such a central role in AF development and progression, drugs that block the mineralocorticoid receptor are generating research interest as potential AF therapies. Spironolactone and a newer experimental compound have shown the ability to prevent fibrotic remodeling of atrial tissue in laboratory settings, reversing the scarring process driven by aldosterone signaling.¹⁴ Spironolactone is already widely prescribed for heart failure and resistant high blood pressure, so repurposing it for AF prevention would not require starting from scratch on safety data. Clinical evidence is still building, but the mechanistic rationale is strong enough that it is being actively studied as an upstream intervention, one that targets the structural substrate for AF rather than just suppressing the abnormal electrical signals once they start.¹³

This is an area where the science of steroids and atrial fibrillation comes full circle. The same mineralocorticoid receptor activity that allows corticosteroids to deplete potassium and promote atrial scarring is also a therapeutic target. Understanding how the body’s own steroid signaling contributes to heart rhythm problems may eventually give clinicians better tools to prevent AF in the first place, rather than simply managing it after it arrives.

1
PubMed. Corticosteroids and the risk of atrial fibrillation
2
Epidemiology. Respiratory Medications and the Risk of Cardiac Arrhythmias
3
PubMed. Corticosteroid Use and Atrial Fibrillation: Exploring Underlying Mechanisms, FAERS Disproportionality Analysis, and a Meta-Analysis of Clinical Studies
4
PubMed Central. Severe Hypokalemia After Corticosteroid Use: A Case of Steroid-Induced Potassium Depletion
5
PubMed. Cardiovascular Disease in Anabolic Androgenic Steroid Users
6
PubMed. Reduced plakoglobin increases the risk of sodium current defects and atrial conduction abnormalities in response to androgenic anabolic steroid abuse
7
PubMed Central. Long-Term Anabolic Androgenic Steroid Use Is Associated with Increased Atrial Electromechanical Delay in Male Bodybuilders
8
PubMed. Atrial fibrillation and anabolic steroids
9
European Heart Journal – Case Reports. Anabolic steroids as the substrate for atrial fibrillation: a case report
10
PubMed Central. Effects of corticosteroids on new-onset atrial fibrillation after cardiac surgery: A meta-analysis of randomized controlled trials
11
The Journal of Thoracic and Cardiovascular Surgery. The effects of steroids on the occurrence of postoperative atrial fibrillation after coronary artery bypass grafting surgery: A prospective randomized trial
12
PubMed Central. Plasma Cortisol and Risk of Atrial Fibrillation: A Mendelian Randomization Study
13
PubMed. Aldosterone and the Mineralocorticoid Receptor in Atrial Fibrillation
14
PubMed Central. The mineralocorticoid receptor promotes fibrotic remodeling in atrial fibrillation
15
JAMA Internal Medicine. Long-term Use of Anti-inflammatory Drugs and Risk of Atrial Fibrillation
16
Cardiovascular Drugs and Therapy. Pharmacodynamic Drug-Drug Interactions and Bleeding Outcomes in Patients with Atrial Fibrillation Using Non-Vitamin K Antagonist Oral Anticoagulants: a Nationwide Cohort Study