Risks of Taking More Than 5mg of Melatonin
Taking more than 5mg of melatonin is generally unnecessary and may increase the risk of side effects such as daytime drowsiness, headache, and dizziness, without providing additional therapeutic benefits. 1, 2
Dosage Recommendations and Efficacy
The American Academy of Sleep Medicine provides clear guidance on melatonin dosing:
- For adults with sleep disorders: 1-5 mg taken 1-2 hours before bedtime is recommended 1
- For specific conditions requiring higher doses:
- Adults with Delayed Sleep-Wake Phase Disorder (DSWPD): 5 mg taken between 7:00-9:00 PM 1
- Patients with REM Sleep Behavior Disorder: starting with 3 mg at bedtime, which may be titrated up to 15 mg if needed (one of the few conditions where higher doses are supported) 1
- Elderly patients: lower doses (1-2 mg) are recommended initially 1
Side Effects of Higher Doses
Research shows that doses exceeding 5mg do not generally provide additional benefits but may increase the risk of adverse effects:
Common side effects of higher doses include:
- Daytime sleepiness (1.66% of users)
- Headache (0.74%)
- Dizziness (0.74%)
- Hypothermia (0.62%) 3
Less common but clinically significant adverse effects that may occur with higher doses:
A 2022 meta-analysis of high-dose melatonin (≥10 mg) found a statistically significant increase in adverse events compared to placebo (Rate Ratio = 1.40 [1.15,1.69], p < .001), though serious adverse events were not increased 2.
Special Populations and Considerations
Higher doses of melatonin require additional caution in certain populations:
- Patients with epilepsy: Potential for interaction, though melatonin can be used to regulate sleep-wake rhythm with appropriate monitoring 1, 4
- Patients taking warfarin: Case reports suggest potential harmful interactions 5
- Patients with hepatic impairment: Require special caution due to altered metabolism 1
- Children: Concerns about potential effects on growth hormone regulation and reproductive function/development with long-term use 1
Proper Administration for Maximum Benefit
To maximize effectiveness while minimizing risks:
- Take melatonin on an empty stomach
- Administer 1-2 hours before bedtime
- Typical target bedtime: 10 pm to midnight 1
- For jet lag: Take close to target bedtime at destination (10pm to midnight) 5
- Avoid taking early in the day as it may cause sleepiness and delay adaptation to local time 5
Key Considerations for Higher Doses
Lack of long-term safety data: Few studies have examined melatonin use beyond 29 weeks, with most lasting 4 weeks or less 3, 6
Diminishing returns: Doses above 5mg appear to be no more effective for most sleep disorders 5
Formulation matters: Short-acting formulations with higher peak concentrations may work better than slow-release formulations for certain conditions 5
Individual variability: Response to melatonin varies significantly between individuals, with some experiencing more pronounced side effects at higher doses 2
Quality control issues: As an over-the-counter supplement in many countries, melatonin products may vary in actual content and purity 5
In conclusion, while melatonin has a generally good safety profile even at higher doses, exceeding 5mg provides little additional benefit for most conditions while potentially increasing the risk of side effects. The only exception is REM Sleep Behavior Disorder, where doses up to 15mg may be warranted under medical supervision.