What is the maximum recommended dosage of melatonin (melatonin) per day for healthy adults?

Maximum Recommended Melatonin Dosage for Healthy Adults

The maximum recommended dosage of melatonin for healthy adults is 15 mg per day, though starting doses should be 3 mg with titration in 3 mg increments only if needed, as lower doses are often more effective than higher doses due to receptor saturation effects. 1

Starting Dose and Titration Strategy

• Begin with 3 mg of immediate-release melatonin taken 1.5-2 hours before desired bedtime 1
• If ineffective after 1-2 weeks of consistent use, increase by 3 mg increments 1
• The maximum dose should not exceed 15 mg per day 1
• Most adults respond adequately to doses between 1-5 mg 2

Why Lower Doses Are Often More Effective

Higher doses (10 mg and above) may paradoxically reduce effectiveness through receptor desensitization or saturation, disrupting normal circadian signaling mechanisms. 1

• Melatonin works by binding to M1 and M2 receptors to suppress REM sleep motor tone and normalize circadian features 1
• Doses between 0.5-5 mg are similarly effective for reducing jet-lag and sleep latency, except that 5 mg produces faster sleep onset than 0.5 mg 3
• Doses above 5 mg appear to be no more effective for most sleep outcomes 3

Adverse Effects Associated with Higher Doses

Morning grogginess, headache, and gastrointestinal upset occur more frequently at higher doses due to melatonin's half-life extending into morning hours. 1

• Clinical trials reported headache (0.74%) and dizziness (0.74%) as the most frequent adverse events 1
• Higher doses (10 mg) were associated with more frequent morning headache and morning sleepiness 1
• Impaired motor function can occur with higher doses 1
• Gastrointestinal upset is reported more frequently at higher melatonin doses 1

Important Safety Considerations and Contraindications

• Use with caution in patients taking warfarin or those with epilepsy due to potential interactions 1, 4
• Melatonin has been associated with impaired glucose tolerance in healthy women after acute administration 4
• Melatonin has been associated with increased depressive symptoms in some individuals 4
• Concurrent medications may interact with melatonin metabolism, potentially amplifying effects of higher doses 1

Product Quality Concerns

Melatonin is regulated as a dietary supplement in the US, raising significant concerns about purity and reliability of stated doses. 1

• No regulatory agency oversees manufacturing or sale in the US 5
• Melatonin concentration of marketed preparations varies widely between product labels and manufacturers 5
• Choose United States Pharmacopeial Convention Verified formulations when possible for more reliable dosing 1, 4

Formulation Considerations

• Immediate-release formulations are generally more effective than slow-release formulations for sleep onset issues 6
• The relative ineffectiveness of 2 mg slow-release melatonin suggests that a short-lived higher peak concentration works better 3
• A study in older adults found that 5 mg melatonin produced maximum concentrations of approximately 4000 pg/mL, substantially higher than physiologic levels, and maintained levels >50 pg/mL for an average of 10 hours 7

Long-Term Use Considerations

• Long-term safety data beyond several months is limited, though available evidence suggests good tolerability 1
• Melatonin at low to moderate dosages (approximately 5-6 mg daily or less) appears safe for long-term use 5
• For intended long-term use, periodic attempts to reduce frequency and dose are indicated 1

Common Pitfalls to Avoid

• Timing is critical: taking melatonin early in the day can cause sleepiness and delay adaptation to local time 3
• Do not assume higher doses are more effective—receptor desensitization may reduce efficacy 1
• Do not rely on product labeling alone due to lack of regulatory oversight in the US 1, 5