Can Fish Oil Pills Cause Heart Palpitations?

October 12, 2025 •

4 min read

Recent research from the Smidt Heart Institute revealed that taking more than 1 gram of fish oil per day can increase the risk of atrial fibrillation, a condition often felt as heart palpitations. While omega-3 fatty acids are celebrated for their health benefits, the relationship between fish oil pills and heart rhythm is more complex than many people realize.

Quick Summary

Higher doses of fish oil supplements have been linked to an increased risk of atrial fibrillation, an irregular heart rhythm that can manifest as palpitations. The effect is dose-dependent, with risks rising at intakes over 1 gram daily. Evidence suggests it's safer to get omega-3s from food sources and to consult a doctor before taking supplements.

Key Points

High Doses Increase AFib Risk: Studies show that taking more than one gram of omega-3 fatty acids per day, particularly from supplements, can elevate the risk of atrial fibrillation, which causes heart palpitations.
Dietary Intake is Safer: Health experts generally agree that getting omega-3s from whole foods like fatty fish is a safer and more heart-healthy approach compared to high-dose supplementation.
Dosage is Key: The risk of irregular heart rhythm appears to be dose-dependent, increasing significantly with higher doses of fish oil.
Vagus Nerve Involvement: High doses of omega-3s may excessively stimulate the vagus nerve, potentially triggering arrhythmias like AFib.
Consult a Doctor: It is critical to speak with a healthcare provider before starting high-dose fish oil supplements, especially if you have a history of heart issues.
Consider Non-Supplement Causes: Many factors other than fish oil, such as stress, caffeine, and other stimulants, can also cause heart palpitations.

The Link Between High-Dose Fish Oil and Heart Palpitations

For years, fish oil has been praised for its cardiovascular benefits, primarily due to its omega-3 fatty acids, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). These essential fatty acids are known to reduce triglycerides, lower blood pressure, and decrease inflammation. However, growing evidence from recent studies and meta-analyses indicates that high-dose supplementation may carry an increased risk of atrial fibrillation (AFib), a type of irregular heart rhythm that can cause palpitations.

Dose-Dependent Risks

The key to understanding the risk appears to be the dosage. A meta-analysis combining results from multiple clinical trials involving over 81,000 patients found a dose-dependent relationship between omega-3 intake and the risk of developing AFib. Patients taking more than 1 gram per day of omega-3 fatty acids had a significantly increased risk compared to those taking less. The risk for AFib was observed to increase mildly at doses around 1,000 mg per day but rose substantially with higher pharmaceutical doses of 1,800 to 4,000 mg daily.

The Vagal Tone Hypothesis

One potential mechanism for this paradoxical effect is related to the vagus nerve, which plays a major role in controlling heart rate. Omega-3 fatty acids can enhance vagal tone in a dose-dependent manner. While low-level vagal stimulation can be antiarrhythmic and reduce the risk of AFib, progressively higher doses of omega-3s may lead to excessive vagal tone, which can paradoxically induce arrhythmias like AFib. This helps explain why low dietary intake of omega-3s is often associated with better heart rhythm, while high-dose supplementation may be linked to a higher risk of arrhythmias.

Fish vs. Supplements: A Cautionary Tale

For heart health, most experts recommend getting omega-3 fatty acids from dietary sources rather than relying on supplements. Whole foods, like fatty fish, contain a wider range of nutrients that work synergistically to support heart health. Moreover, some studies have shown that eating fish is more effective at preventing cardiovascular disease than taking supplements. The UK Biobank study, for example, found that regular fish oil supplement use was associated with an increased risk of AFib in people without pre-existing cardiovascular disease.

Managing Heart Palpitations

If you experience heart palpitations while taking fish oil, it is crucial to consult a healthcare provider. The best course of action depends on the underlying cause. If a doctor rules out a serious heart condition, managing palpitations can often be achieved through lifestyle adjustments.

Non-Fish Oil-Related Causes of Heart Palpitations

Stress and anxiety
Excessive caffeine or alcohol consumption
Stimulant medications (e.g., some cold/cough medicines)
Hormonal fluctuations (e.g., during pregnancy or menopause)
Dehydration
Strenuous exercise
High-carb, high-fat, or sugary meals

Actions to Help Alleviate Palpitations

Practice Relaxation Techniques: Deep breathing exercises, yoga, and meditation can help manage stress and reduce anxiety-induced palpitations.
Avoid Triggers: Limit or avoid caffeine, alcohol, and nicotine.
Stay Hydrated: Dehydration can put extra strain on the heart, so drinking plenty of water is essential.
Explore Vagal Maneuvers: Techniques such as splashing cold water on your face can help stimulate the vagus nerve and slow a racing heart.

Comparison of Omega-3 Sources: Food vs. Supplements


Feature	Omega-3 from Fatty Fish (e.g., Salmon)	Omega-3 from Supplements (e.g., Fish Oil Pills)
Associated Health Risk	Consistently linked to lower risk of heart disease.	Conflicting evidence; some studies show increased AFib risk, especially at high doses.
Nutrient Profile	Provides EPA, DHA, and a wide array of other nutrients like vitamin D, calcium, and protein.	Isolated EPA and/or DHA; purity and concentration can vary, though some are highly purified.
Dosage Control	Dependent on serving size; less concentrated and generally lower intake overall.	High doses are easily achievable, increasing the risk of side effects like bleeding and AFib.
FDA Regulation	Not applicable; whole food source.	Varies; over-the-counter supplements are not as strictly regulated as prescription medications.
Best for...	General heart health and wellness for most people.	Individuals with severely high triglycerides, under a doctor's supervision.

Conclusion

While fish oil supplements are a popular choice for boosting omega-3 intake, recent and emerging evidence warrants caution, especially concerning potential links to heart palpitations through atrial fibrillation. The risk appears to be dose-dependent, with higher intake increasing the likelihood of irregular heart rhythms. For most individuals, acquiring omega-3s from dietary sources like fatty fish is the safer and more effective approach for overall cardiovascular wellness. It is imperative to discuss any supplement regimen with a healthcare professional, especially if you have pre-existing heart conditions or experience palpitations. In the event of palpitations, identifying and avoiding non-fish oil triggers is also a crucial step in management.

For more information on supplements and heart health, consider reviewing resources from authoritative health institutions, such as the American Heart Association.

Frequently Asked Questions

The risk of heart palpitations due to fish oil appears to be primarily associated with high doses (over 1 gram per day). Low doses, such as those obtained from a diet rich in fatty fish, are not typically linked to this side effect and are generally considered safe for heart health.

Individuals with pre-existing heart conditions, particularly those with a history of irregular heart rhythms (arrhythmias) or other risk factors for heart disease, may be more susceptible to palpitations when taking high-dose fish oil supplements.

No, atrial fibrillation (AFib) is a specific type of irregular heart rhythm, whereas heart palpitations are the feeling or sensation of the heart pounding, racing, or fluttering. AFib can cause palpitations, but palpitations can also result from many other factors, most of which are harmless.

If you experience palpitations, especially in conjunction with chest pain, shortness of breath, or dizziness, seek immediate medical attention. If symptoms are mild, reduce your dosage or stop taking the supplement and consult your doctor to determine if the fish oil is the cause.

No. The risk of arrhythmias appears to be associated with specific types and high dosages of omega-3s found in some supplements, particularly those with high levels of both EPA and DHA. Prescription-grade omega-3 medications are more concentrated than over-the-counter supplements and carry specific prescribing information.

Consuming fatty fish is generally considered a safer and more heart-healthy way to obtain omega-3s. The omega-3 content in fish is less concentrated than in supplements, and fish provides additional protective nutrients that are not present in supplements.

A doctor can help you determine the cause by reviewing your medical history, current medications, lifestyle, and supplement use. They may also order tests like an electrocardiogram (ECG) or Holter monitor to assess your heart's electrical activity.