Melatonin Overdose: Effects and Recommendations

Although melatonin is produced naturally in the body, there are synthetic compounds containing this substance. Why should overdose be avoided?
Melatonin Overdose: Effects and Recommendations
Maryel Alvarado Nieto

Written and verified by the doctor Maryel Alvarado Nieto.

Last update: 16 September, 2022

A melatonin overdose can lead to health side effects. This hormone is naturally produced in the pineal gland and is involved in the circadian sleep-wake rhythm. This means that its secretion affects sleep patterns.

For this reason, it’s also available as a drug, as it’s an adjuvant for sleep difficulties. And, although it’s considered a relatively safe drug, there are some adverse effects that should be considered before taking it.

How is melatonin produced?

The hormone is synthesized from a precursor molecule, serotonin. This is modified by the action of enzymes. In general terms, its secretion is regulated by neurons located in the hypothalamus, which indicate when and in what quantity it is produced.

In turn, these neurons are stimulated by cells located in the retina, which are activated in the absence of light. Therefore, maximum secretion occurs in complete darkness.

A person with a pill.
The synthetic form of melatonin is used to treat sleep disorders.

What is it used for?

Although, in theory, the usefulness of the substance is broad, the studies justifying its use are usually small in scope. This has led to melatonin not having sufficient consensus approval for the management of various sleep disorders.

Moreover, neither is there any agreement as to which age it can be used from. Even so, it’s often prescribed in certain conditions, such as the following:

  • Insomnia
  • Sleep phase disturbances
  • Irregular sleep-wake rhythm
  • Sleep resynchronization in shift work
  • Jet lag
  • Some dementias, such as Alzheimer’s disease.
  • Circadian rhythm synchronizations in blind patients.

In addition to the scarce documentation on its use, errors in the prescription of melatonin are also described.

Firstly, due to poor training of primary care personnel on sleep disorders.

Secondly, because the substance can be found in two different forms of presentation; fast-acting and extended-release. Each has specific indications, which some people choose to ignore.

Melatonin overdose and its effects

Melatonin overdose is one of the most common mistakes made when using this substance. In the search for better effects, some people tend to overuse it.

Likewise, as it’s classified as a nutritional supplement, it’s often used on the recommendation of people who are not qualified to do so. As it’s a molecule with effects on the central nervous system, its prescription should be professionally monitored.

Among other things, there’s little documentation on melatonin overdose. In general, it’s considered a fairly safe molecule, since few adverse effects are described, and they aren’t usually serious.

Likewise, a maximum recommended daily dose hasn’t been established, but in usual practice between 1 and 10 mg per day are prescribed, always taking into account the patient’s age and the disorder to be treated.

Side effects

Although the literature on this subject is scarce, some adverse effects due to melatonin overdose have been described. In general, these are transient symptoms that aren’t serious and improve when the medication is discontinued.

However, the documentation of some more serious side effects tend to worry patients and families, so it’s important to clarify the frequency of such symptomatology.

Does melatonin have an increased risk of producing seizures?

Some experts fear that melatonin may cause seizures, especially in children. This fear originates from a study in which six pediatric patients – with significant neurological conditions – received treatment with melatonin and four of them reported seizures.

The main drawback with this result is that the underlying brain lesions could have been the cause of the seizure and not the medication. In addition, the population studied was small, so it doesn’t represent a significant sample. More research is needed.

Other authors make it difficult to reach a conclusion on this theory, as there are reports with contrary results. These reports describe improvements in epileptogenic activity in patients using melatonin. Therefore, its use should always be in the hands of a specialist.

Increased drowsiness

In contrast, high doses have caused increased drowsiness in patients, but these amounts aren’t usually used in the general population. In contrast, usual doses generate a synchronization of the sleep-wake cycle, which improves sleep patterns and daytime alertness.

To obtain these results it’s necessary to establish an accurate diagnosis in order to enable effective treatment.

Other adverse reactions that may occur with melatonin

In addition, other side effects of using the “darkness hormone” have been documented, but these are usually infrequent and reverse over time without major significance. These symptoms are considered trivial, as they don’t pose a threat to the patient.

Even so, if they do cause sufficient discomfort, discontinuation of the drug ameliorates such effects. These adverse reactions include the following:

  • Headaches
  • Disorientation
  • Abdominal pain
  • Skin rashes
A woman with a headache.
Melatonin overdose can trigger headaches, digestive discomfort, dizziness, and disorientation.


The regulation of sleep patterns is the main reason why melatonin is used. There are a number of situations that interfere with nighttime rest that can be worked on to avoid over-medication. However, assessment by trained personnel is ultimately the most important action in deciding whether melatonin treatment is the most appropriate.

Often, timely improvements in sleep hygiene make it possible to regulate the quality of rest, as disorders are secondary to bad habits. Among these recommendations, the following are worth highlighting:

  • The willingness to go to bed at the same time each day
  • Sleeping in complete darkness
  • Avoiding sources of distraction such as electronic devices in the bedroom.

On the other hand, the ideal time to take melatonin depends on the purpose of its use. In this sense, it’s suggested that you follow the recommendations of a physician with experience in managing this supplement.

In fact, depending on the circumstances, sometimes it’s prescribed during the day and other times at night. As for the dosage, it can be up to 300 mg without observing any serious adverse effects. Despite this, low doses are usually handled.

Precautions with the use of melatonin

To conclude, it’s important for the consumption of melatonin to be under medical supervision. Ideally, these recommendations should come from a specialist, thus freeing up doctors in primary care.

Special caution should be taken in patients with underlying diseases, such as those with autoimmune disorders, hematological disorders, asthma, diabetes, and epilepsy.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

  • Morera, A.; Henry, M.; De la Varga, M.; Seguridad en el Uso de la Melatonina; Actas Españolas de Psiquiatría; 29 (5): 334 – 337; 2001.
  • Zhang, B.; Kassim. S.; Harrouk, W.; Asante, K.; Melatonin Pharmacy Compounding Advisory Committee Meeting; United States Food and Drugs Administration; 2021.
  • de Rosula, G.; Plus, K.; Clindareach, K.; Melatonina: Usos, Efectos Secundarios, Interacciones, Dosis y Advertencias; 2022.
  • Escames, G.; Acuña, D.; Melatonina, Análogos Sintéticos y el Ritmo Sueño/Vigilia; Revista de Neurología; 48 (5): 245 – 254; 2009.
  • Arboledas, G.; Merino, M.; de la Calle, T.; Hidalgo, M.; Rodríguez, P.; Soto, V.; Madrid, J.; Consenso sobre el Uso de Melatonina en Niños y Adolescentes con Dificultades para Iniciar el Sueño; Anales de Pediatría; Asociación Española de Pediatría; XXX (XX): XXX.e1 – XXX.e9; 2014.
  • Jiménez, G.; Ugalde, O.; Ortíz, L.; Ramírez, G.; Benítez, G.; La Melatonina: un Coadyuvante Potencial en el Tratamiento de las Demencias; Salud Mental; 31: 221 – 228; 2008.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.