Supplements that can induce bradycardia
Bradycardia has been reported with several nonprescription supplements, most commonly when supplements contain or are adulterated with cardiac glycosides (digoxin- or digitoxin-like cardiotoxins) or when supplements are contaminated with toxic metals that can cause multisystem toxicity. [1], [2], [3], [4]
Cardiac-glycoside–containing supplements
Cardiac glycosides can produce digoxin-like effects on cardiac conduction and rhythm, including marked sinus bradycardia and atrioventricular (AV) block. [1], [2], [3]
- Tejocote root (Crataegus mexicana) marketed as a weight-loss supplement has been associated with severe bradycardia and second-degree AV block. [1]
- Unknown “herbal cleansing” preparations containing cardioactive steroids (digitoxin-like compounds) have been associated with profound bradycardia (pulse ~30 beats/min) and digitalis-type ECG changes. [2]
- Adulterated botanical weight-loss supplements have been linked to digoxin-like intoxication with sinus bradycardia and AV block. [3]
Botanical cardiac glycoside adulteration
Yellow oleander (Thevetia peruviana) has been identified in an ingested weight-loss supplement label despite absence of the advertised ingredient, with electrocardiographic sinus bradycardia reported. [3]
Heavy-metal contamination from supplements
Heavy-metal exposure from contaminated supplements can cause bradycardia as part of broader toxicity. [4]
- Algae-based supplements (specifically reported for spirulina and chlorella) have been described as susceptible to arsenic contamination and have been associated with sinus bradycardia in a case report. [4]
Berberine supplements with bradycardia
Bradycardia has been reported in association with berberine supplement use in a case report, in the context of hypoglycemia and ECG conduction abnormalities. [5]
Initiation risk factors for supplement-associated bradycardia
A key clinical risk factor is supplement use in the setting of new symptomatic bradycardia (such as syncope, weakness, dizziness) or ECG conduction abnormalities after starting or escalating a supplement regimen. [1], [2], [3], [4], [5]
Common clinical pitfalls to avoid
Bradycardia can be missed or misattributed when toxic supplement exposure is not captured in medication history because supplement ingredients may be unlabeled, mislabeled, or adulterated. [3], [2]
Urgent evaluation considerations
Marked bradycardia with AV block, syncope, or hypotension after supplement ingestion should be treated as a potential toxidrome and evaluated urgently with ECG and toxicology-directed testing. [1], [2], [3]
Supplements implicated (practical list)
- Tejocote root (Crataegus mexicana) weight-loss supplements. [1]
- Herbal cleansing preparations containing cardioactive steroids (digitoxin-like compounds). [2]
- Botanical weight-loss supplements adulterated with yellow oleander (Thevetia peruviana). [3]
- Arsenic-contaminated algae supplements (spirulina, chlorella). [4]
- Berberine supplements (case report with bradycardia during hypoglycemia and conduction abnormalities). [5]