Can melatonin cause cardiac complications?

Does Melatonin Cause Cardiac Complications?

Melatonin is considered safe for perioperative and general use with no significant cardiac complications in the vast majority of patients, though rare case reports suggest potential for ventricular arrhythmias in susceptible individuals. 1

Safety Profile from Guidelines

The Society for Perioperative Assessment and Quality Improvement (SPAQI) explicitly recommends continuing melatonin through the perioperative period, stating that "available evidence demonstrates melatonin is safe in the perioperative period." 1 This recommendation stands in contrast to many other supplements that require discontinuation due to cardiovascular concerns, underscoring melatonin's favorable safety profile. 1

The American Academy of Sleep Medicine guidelines consistently report that no serious adverse reactions have been documented in relation to melatonin use across age groups, including children and adults. 2 The most frequently reported adverse events in clinical trials were headache (0.74%) and dizziness (0.74%), with no mention of cardiac complications as a common concern. 2

Cardiovascular Effects: Predominantly Beneficial

Research evidence suggests melatonin has cardioprotective rather than cardiotoxic properties in most contexts:

• Melatonin demonstrates anti-inflammatory, antioxidant, and anti-hypertensive effects that may benefit cardiovascular function. 3, 4
• A 2025 meta-analysis found melatonin improved quality of life in heart failure patients and showed trends toward improved ejection fraction and NYHA functional class. 5
• Melatonin may reduce blood pressure through multiple mechanisms including direct hypothalamic effects, antioxidant activity, decreased catecholamine levels, and smooth muscle relaxation. 6
• Patients with coronary heart disease have been found to have low melatonin production rates, suggesting endogenous melatonin may be protective. 6

Rare Arrhythmia Risk: Important Caveat

The single most important cardiac concern is a 2017 case report documenting ventricular arrhythmias in two patients with structurally normal hearts. 7 This represents the first human evidence of potential proarrhythmic effects, where symptomatic premature ventricular contractions (PVCs) occurred while taking melatonin and resolved upon discontinuation. 7 However, this remains an isolated report with only two cases, and idiopathic ventricular arrhythmias are relatively common in the general population regardless of melatonin use. 7

Specific Precautions

The American Academy of Sleep Medicine recommends caution in certain populations:

• Patients taking warfarin: Potential interactions have been reported to the World Health Organization. 8
• Patients with epilepsy: Use with caution based on case reports. 8
• Patients on photosensitizing medications: Periodic ophthalmological/dermatological monitoring recommended. 8
• Patients with impaired glucose tolerance: Melatonin has been associated with impaired glucose tolerance in healthy women after acute administration. 8

Practical Clinical Algorithm

For patients without structural heart disease or arrhythmia history:

• Melatonin can be safely recommended at standard doses (3-5 mg). 1, 2
• No cardiac monitoring is required. 1
• Continue through perioperative periods. 1

For patients with known arrhythmias or frequent PVCs:

• Consider alternative sleep interventions first. 8
• If melatonin is used, counsel patients to report new palpitations or worsening symptoms. 7
• Discontinue immediately if new arrhythmias develop. 7

For patients with heart failure:

• Melatonin may provide additional cardiovascular benefits beyond sleep improvement. 5
• Standard dosing (3-5 mg) appears safe and potentially beneficial. 5

Dosing Considerations for Safety

Lower doses may be safer than higher doses, as higher doses (10 mg) can cause receptor desensitization and are associated with more frequent adverse effects including morning headache and sleepiness. 2 The American Academy of Sleep Medicine recommends starting with 3 mg of immediate-release melatonin, with dose titration in 3 mg increments only if needed, up to a maximum of 15 mg. 2

Quality Control Concern

Melatonin is regulated as a dietary supplement in the US, raising concerns about purity and reliability of stated doses. 1, 2 Choose United States Pharmacopeial Convention Verified formulations when possible for more reliable dosing and to minimize risk of contaminants that could theoretically cause cardiac effects. 2, 8