Key Takeaways
  • A melatonin overdose occurs after taking an excessive amount and is influenced by factors like age, gender, health conditions, and timing.
  • Melatonin users should be wary of inaccurate dosages on labels and should never consume more than the recommended amount.
  • Common symptoms of melatonin overdose include excessive sleepiness, stomach problems, and headaches. Extremely high doses can potentially cause cardiovascular issues.
  • Consult a healthcare provider before taking melatonin or giving melatonin to children.

Melatonin is a hormone that plays a significant role in the regulation of sleep and circadian rhythms. Dubbed the sleep hormone, melatonin is formed in the brain’s pineal gland in response to falling light levels to prepare the body for sleep.

In recent years, melatonin supplements marketed to treat a variety of sleep disorders have become common. From 2007 to 2012, melatonin use in the U.S. doubled and it now ranks as one of the nation’s most popular supplements. Its popularity stems in part from its image as a natural alternative to traditional sleep medications, which are known for side effects. However, this does not mean melatonin supplements are harmless.

It is important to be aware of the safety risks posed by taking too much melatonin. We take a closer look at melatonin dosing, potential symptoms of a melatonin overdose, and when to contact a doctor.

How Much Melatonin Is Safe to Take?

Melatonin is available to purchase in any quantity, without a prescription in the U.S. However, there is currently no formal consensus on the optimal dosing regimen for this supplement.  Studies frequently use doses ranging from 0.1 to 10 milligrams , but 1 to 5 milligrams is often considered an appropriate amount to start.

There are many challenges to determining the appropriate amount of melatonin for any one person to take. Individual responses to this supplement can vary considerably due to factors that are not fully understood but can include age, gender, specific sleep issues, other health conditions, and timing of administration.

Infographic explaining melatonins half-life and dosage guidelines.

In addition, not all melatonin supplements are created equal. Differences in preparation can significantly alter melatonin’s impact. Depending on the formulation, taking 1 to 10 milligrams of melatonin can raise the body’s melatonin blood levels anywhere from 3 to 60 times the normal amount.

Melatonin users should also be wary of the dosages listed on supplement labels, which have shown to be alarmingly inaccurate. A random sampling  of 31 brands of melatonin supplements determined that most did not contain the labeled dose, with the actual amount ranging anywhere from less than 80% to nearly 500% as much. Additionally, over one quarter of the supplements contained serotonin.

Despite the lack of data and variability around dosing regimens, with typical use, melatonin is largely considered safe and is generally well-tolerated in healthy adults. The risk of side effects is low, but can include mild headache, dizziness, nausea, and sleepiness.

Finding Reputable Sleep Supplements

The safety and efficacy of supplements is not closely monitored by the U.S. Food and Drug Administration (FDA). Shoppers should take additional measures to make sure they are purchasing reputable products.

Can You Overdose on Melatonin?

So far, there is no clinical evidence that short-term melatonin use can cause long-term problems in healthy adults. However, it is important to discuss melatonin supplementation with your doctor, as they can help you determine the proper dosage. Starting with the lowest possible dose is typically recommended. This can help prevent unwanted side effects.

It is also important to note that high-quality studies addressing higher doses of melatonin are lacking. The current body of evidence consists mostly of small studies and case reports.

In one study, 12 adult males were administered intravenous melatonin in doses of 10 milligrams, 100 milligrams, or a placebo. There were no reported differences in sedation among the groups, and there were no harmful reactions. A second study gave five patients 1,000 milligrams of oral melatonin for approximately four weeks.  While changes in pituitary hormones were observed, no toxic effects were reported.

What Are the Symptoms of a Melatonin Overdose?

Unwanted or troubling side effects can occur with any supplement, even if it is considered relatively safe. Concerning symptoms have been reported with higher doses of melatonin.

Possible symptoms of too much melatonin include:

  • Headache
  • Hypotension (low blood pressure)
  • Hypertension (high blood pressure)
  • Drowsiness
  • Vomiting
  • Worsening of alopecia areata (an autoimmune disorder causing hair loss)

Because melatonin can affect the cardiovascular, dermatologic, and central nervous systems, those with other conditions may be vulnerable to additional risks. Evidence suggests that melatonin supplementation may induce depression , particularly in people predisposed to or currently experiencing it. Research on this topic, however, is conflicting, since some studies have demonstrated the potential for melatonin to treat depression .

People taking blood thinners and benzodiazepines should be careful, as there is a possibility for interaction . Those with epilepsy should also exercise caution, as melatonin has been associated with increased seizures. People who are currently taking other medications or supplements should discuss potential interactions directly with their doctor before taking melatonin.

Research suggests that elderly people, who have lower natural levels of melatonin , may be more sensitive to the effects of melatonin supplements. Therefore, older people are encouraged to check with their doctor before taking melatonin and start with the lowest possible dose.

What Do I Do If I’m Experiencing Symptoms of a Melatonin Overdose?

Compared with most other sleep aids, melatonin clears the body quickly, and its effects are short-lasting. If you are experiencing unwanted symptoms after taking melatonin, you can most likely just wait it out as your body processes the drug. However, when in doubt, it’s always a good idea to seek professional advice. Don’t hesitate to contact your doctor or local poison control for guidance on managing worrisome symptoms or determining whether you need medical care.

What Are the Long-Term Effects of Taking Melatonin?

Minimal research exists on using melatonin beyond a few months. Therefore, there is much we do not know about its long-term effects. There is not even agreement on what constitutes long-term melatonin use.

Most of the concern around taking melatonin for extended periods centers around it’s potential to affect reproductive hormones. While the exact mechanism of action is still unclear, some reports indicate that melatonin may inhibit reproductive hormones .

Is Melatonin Safe for Children?

Further research is needed regarding the safety of melatonin for children.

Nearly 25% of children have difficulty sleeping , and parents increasingly turn to melatonin for help. Between 2007 and 2012, pediatric melatonin use rose seven-fold and is now the second most common natural supplement in this age group.

Despite its prevalence, there are reasons for parents to be cautious about using melatonin. It appears that children may be particularly vulnerable to the possible effects of this supplement on reproductive hormones. Melatonin has been associated with puberty delays , irregular menstruation, and overproduction of the hormone prolactin.  It is important to note, however, that research on this topic is conflicting , and experts agree that the topic is understudied.

Parents should also be aware that melatonin may decrease blood pressure or serum glucose levels . Children taking other medications or who have illnesses affecting these systems should consult their doctor before starting melatonin.

Melatonin should only be used for children under the guidance of a doctor. Most pediatric sleep disorders can be managed with behavioral changes, such as proper sleep hygiene and cognitive therapy. Melatonin should not be used before trying other measures.

When Should I Talk With a Doctor?

While melatonin is largely viewed as safe, it is not without risk. Perhaps the most significant risk is what we do not know about this supplement. While you are unlikely to cause any serious damage using melatonin, it’s best to proceed with caution. Seeing a doctor for an accurate diagnosis of a sleep condition can help you determine whether melatonin is suitable for your situation.

Medical Disclaimer: The content on this page should not be taken as medical advice or used as a recommendation for any specific treatment or medication. Always consult your doctor before taking a new medication or changing your current treatment.

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