What supplements induce bradycardia (abnormally slow heart rate)?

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From the Guidelines

Bradycardia can be induced by various supplements, including omega-3 fatty acids, magnesium, melatonin, valerian root, hawthorn, motherwort, potassium, and CBD oil, which can affect heart rate by influencing ion channels, the autonomic nervous system, or interacting with heart medications, as noted in studies such as 1 and 1.

Key Supplements to Watch

  • Omega-3 fatty acids (fish oil) in high doses exceeding 3 grams daily
  • Magnesium supplements, particularly when doses exceed 350 mg daily
  • Melatonin, especially at doses above 5 mg
  • Herbal supplements like valerian root, hawthorn, and motherwort
  • Potassium supplements, particularly in people with kidney issues or those taking certain medications
  • CBD oil, which has been reported to cause bradycardia in some individuals

Mechanism of Action

These supplements can cause bradycardia by:

  • Affecting ion channels in cardiac cells
  • Influencing the autonomic nervous system
  • Interacting with medications like beta-blockers or calcium channel blockers, as discussed in 1 and 1

Precautions

People with pre-existing heart conditions, the elderly, and those taking heart medications should be particularly cautious with these supplements and consult healthcare providers before use, due to the potential risks outlined in 1 and 1.

Symptoms to Watch

Symptoms of bradycardia to watch for include:

  • Dizziness
  • Fatigue
  • Weakness
  • In severe cases, fainting It is essential to prioritize caution and consult healthcare providers before using any supplements, especially for individuals with pre-existing heart conditions or those taking medications, as emphasized in 1 and 1.

From the Research

Supplements and Bradycardia

There is limited research on supplements that induce bradycardia (abnormally slow heart rate). However, some studies suggest that certain supplements may have an effect on heart rate:

  • Omega-3 polyunsaturated fatty acids (N-3 PUFA) or fish oil supplementation may reduce mortality and sudden death, but its effect on heart rate is not explicitly stated 2
  • Coenzyme Q10, used in treatment of heart failure, may have beneficial effects on arrhythmias, but its effect on heart rate is not explicitly stated 2
  • Magnesium supplementation may be beneficial in the treatment of torsades de pointes and in some studies after cardiac surgery, but its effect on heart rate is not explicitly stated 2, 3
  • Potassium supplementation may have a modest blood pressure-lowering effect in normotensive persons with low dietary intake, but its effect on heart rate is not explicitly stated 4, 5
  • Calcium and magnesium supplements do not appear to have a significant effect on blood pressure or heart rate 4, 5

Herbal Supplements

Some herbal supplements may cause adverse cardiovascular effects, including changes in heart rate:

  • Herbal stimulants, such as bitter orange, ephedra, caffeine, guarana, maté, kola, areca, lobelia, and khat, may cause cardiovascular effects, including changes in heart rate 6
  • Other herbal ingredients may also have adverse cardiovascular effects, but the specific effects on heart rate are not explicitly stated 6

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Magnesium and Cardiovascular Disease.

Advances in chronic kidney disease, 2018

Research

Safety of herbal supplements: a guide for cardiologists.

Cardiovascular therapeutics, 2010

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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