Supplements Associated With Bradycardia
Several dietary supplements and herbal products have demonstrated the ability to induce bradycardia through cardiac-glycoside–like toxicity or through direct electrophysiologic effects seen in preclinical models. [1], [2]
Cardiac-Glycoside–Containing Herbal Products
- Plant adulterants or mislabeled “weight loss” or “traditional” herbal products may contain cardiac glycosides that can produce digoxin-like toxicity, which commonly includes sinus bradycardia. [1]
- Example adulterant confirmed in a supplement case: yellow oleander (Thevetia peruviana) detected by forensic toxicology in a mislabeled product, with electrocardiographic sinus bradycardia documented. [1]
Herbal Components With Bradycardic Effects in Preclinical Models
Preclinical embryonic heart–rate assays have shown bradycardia after exposure to several commonly used complementary medicine active components.
- Allicin (from garlic) has demonstrated embryonic bradycardia in vitro. [2]
- Epigallocatechin gallate (EGCG, from green tea) has demonstrated embryonic bradycardia in vitro. [2]
- Ginsenoside Rg3 (found in ginseng) has demonstrated embryonic bradycardia in vitro. [2]
- Berberine (from goldenseal) has demonstrated embryonic bradycardia in vitro. [2]
Mechanistic Considerations
Cardiac-glycoside–like toxicity can slow cardiac conduction and heart rate, producing bradycardia patterns on electrocardiography. [1]
Initiation Triggers for Clinical Concern
Clinical concern for supplement-induced bradycardia is highest when bradycardia occurs after:
- Recent ingestion of imported or online-purchased herbal supplements with uncertain contents. [1]
- Use of products that may be adulterated with botanical cardiac glycosides. [1]
- Co-occurrence of digoxin-like toxicity features such as nausea, vomiting, hypotension, and conduction abnormalities. [1]
Common Pitfalls to Avoid
- Assuming that “natural” supplements are unlikely to cause clinically significant bradycardia is unsafe. [1]
- Assuming labeled ingredients match actual product contents is unsafe because forensic analysis has confirmed mislabeling in a bradycardia case. [1]
Targets of Evaluation for Suspected Supplement-Induced Bradycardia
- Electrocardiography should be used to document bradycardia and conduction abnormalities when supplement toxicity is suspected. [1]
- Toxicology and product-content verification should be pursued when digoxin-like toxicity is suspected from an herbal supplement. [1]