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What is melatonin?

Melatonin is a hormone the pineal gland produces to help regulate sleep–wake cycles.¹ It is synthesized naturally in the body using tryptophan, an amino acid.

A healthy brain produces melatonin in response to darkness, which helps establish a circadian rhythm.² Circadian rhythms are the physical, mental, and behavioral processes that follow a regular 24-hour schedule. Examples include waking in the morning when it becomes light and sleeping at nighttime.³

Darkness triggers the body’s release of melatonin. The hormone then activates certain brain, eye, and other receptors to regulate the body’s sleep–wake cycles and circadian rhythms.

Synthetic, animal, and microorganism versions of melatonin are used to produce over-the-counter (OTC) dietary supplements. Their ingredients are not regulated, and their contents are variable. These melatonin-based products may contain more or less melatonin than stated on the label. Research studies have shown that OTC melatonin supplements contain contaminants like serotonin.⁴

Since the US Food and Drug Administration (FDA) does not regulate dietary supplements, melatonin is not FDA-approved to treat any specific condition.

Despite being sold over the counter, melatonin should be taken under a doctor’s supervision.

What is melatonin used to treat?

Because of its role in regulating natural sleep cycles, the American Academy of Family Physicians considers melatonin a key pharmacological treatment for insomnia.⁵

Additionally, melatonin is typically used therapeutically in sleep–wake cycle disorders such as those seen in jet lag and with people working a nontraditional schedule.⁶

The hormone has also been used to treat a type of insomnia in people with blindness called non-24-hour sleep–wake rhythm disorder.⁷

Melatonin is also an antioxidant that has been associated with supporting cardiovascular, reproductive, and bone health.⁸

Although melatonin has been used by some in the treatment of depression, chronic pain, and even COVID-19, the available research has not proven its efficacy in those conditions.⁹

How do you take melatonin?

Melatonin sales in the US have increased significantly over the past few years.¹⁰

OTC melatonin supplements are available in various forms, including liquids, chewable gummies, and tablets for oral dosing, along with transdermal patches and rectal suppositories.¹¹ These may be formulated for immediate release, extended release, or a combination of both.

The most commonly used forms of melatonin are capsules and tablets.¹²

The FDA doesn’t regulate the contents of melatonin supplements or how much you should take. They are available in a variety of strengths, and there are no clear dosing guidelines.

In clinical trials, doses between 0.1 and 10.0mg were used up to two hours before bedtime.¹³ To find better quality melatonin supplements with more accurate dosing information, it’s best to look for those approved by the nonprofit organization United States Pharmacopeia. Such products will be labeled “USP verified.”¹⁴

Lower-dose formulations are available for children. However, these should be given with caution, as hospitalizations related to melatonin ingestion in individuals aged 19 years and under have risen in the last ten years.¹⁵

A review of clinical studies looking at melatonin use for jet lag found that people fell asleep faster and slept better when taking 5mg. Taking a dose higher than 5mg was not found to be more effective.¹⁶

Immediate-release supplements were found to be more effective for treating jet lag than the extended-release forms.

In addition, studies have found that melatonin given in physiologic doses of 0.1–0.3mg effectively helps with falling and staying asleep, while doses of 0.5mg and higher impact the phases of sleep.¹⁷

Follow the instructions on the dietary supplement label, and talk to your doctor for dosing instructions for your specific sleep-related symptoms.

Seeing results

When taking immediate-release melatonin orally, you’ll typically start to feel its sleep-enhancing effects within about one hour.¹⁸

Compared to extended (prolonged)-release formulations, the immediate-release form reaches peak plasma levels more quickly, meaning you’ll feel the effects sooner.

However, immediate-release formulas also demonstrate a shorter half life of the drug, meaning the drug leaves your body faster than with extended-release formulations.

The prolonged-release formulations take longer to act, peaking in 3–4 hours. The effects last longer, helping you stay asleep throughout the night.¹⁹

Who should not take melatonin?

Short-term use of melatonin supplements appears to be safe for many people.

However, you should avoid melatonin or consult your doctor before taking it if you have the following conditions:²⁰ ²¹

  • Seizure disorder

  • Dementia²²

  • Bleeding disorders or taking anticoagulant medications

  • Severe kidney or liver disease

  • Hypertension (high blood pressure)

  • Depression

  • Autoimmune disorders or taking immunosuppressant drugs after a transplant

  • During pregnancy or while breastfeeding 

Potential side effects of melatonin

In addition to its benefits for the treatment of insomnia and other sleep disorders, melatonin may cause side effects in some people.

Common side effects

These include any of the following:²³

  • Increased daytime sleepiness

  • Dizziness

  • Headaches

  • Dry mouth and skin itchiness

  • Irritability

  • Vivid dreams

  • Night sweats

  • Arm and leg pains

In addition, melatonin has been reported to affect certain body systems in the following ways:²⁴

  • Central nervous system: headaches, sleepwalking, nightmares, seizures

  • Cardiovascular system: hypotension or hypertension, palpitations

  • Gastrointestinal system: heartburn, gas, stomach pain and abdominal cramping, nausea, vomiting, diarrhea

  • General: sweating, hot flashes, reduced body temperature

Common side effects in children include drowsiness, bed wetting, headaches, nausea, diarrhea, and dizziness.²⁵

There has been concern that melatonin, since it’s a hormone, may interfere with growth and development. There is insufficient research to prove or disprove this assertion, so it should be used with caution in the pediatric population.²⁶

Severe side effects

Though uncommon, reported severe adverse effects include the following:

  • Elevated levels of hopelessness or sadness

  • Blurry vision

  • Passing out, feeling faint, or vertigo (a spinning sensation)

  • Difficulty breathing

  • Rapid heart rate

When to seek medical help

If you experience any severe side effects after taking melatonin, seek immediate medical attention.

Overdose information

Melatonin isn’t a medication. It has a high safety profile, and taking even a large dose of the supplement doesn’t usually result in significant toxicity.²⁷

Symptoms of an overdose may include the following:²⁸ ²⁸

  • Excessive fatigue or sleepiness

  • Nausea, vomiting

  • Rash

  • Gastritis

  • Agitation

  • Headaches

Contact the National Poison Control helpline if you or someone you know develops symptoms that aren’t life-threatening. The person should be supervised until their symptoms subside.

Seek emergency medical attention for any severe overdose symptoms.

Allergy information

Serious allergic reactions to melatonin are rare.

Symptoms of an allergy may include the following:

  • A skin rash, hives, or itching

  • Tightness in the chest or throat

  • Wheezing

  • Trouble breathing or talking

  • Vomiting

  • Swelling of the face, tongue, or throat

  • Fainting or loss of consciousness

Call 911 or go to the closest emergency department immediately if you experience these or any other life-threatening symptoms.

Long-term use of melatonin

While melatonin has generally been shown to be safe for short-term use, clinical evidence of its long-term safety and benefits for adults and children is relatively sparse.³⁰

Studies of its use from six to 12 months have shown no evidence of adverse effects.³¹

Research in children with autism spectrum disorder taking melatonin nightly over a two-year period showed no negative effects on puberty, height, or BMI, and no withdrawal symptoms were seen.³²

Melatonin and pregnancy

Recent studies have demonstrated that melatonin use during pregnancy or while breastfeeding is not associated with negative health outcomes for the mother or baby. However, because there has been insufficient research to clearly demonstrate safety, you should consult a healthcare professional before taking it during pregnancy or while breastfeeding.³³

Clinical studies on the effects of taking melatonin while breastfeeding are lacking. There is no specific indication of its safety for the infant or its impact on breast milk production.³⁴

Additionally, since melatonin is unregulated, there is no assurance of the amounts specified and other ingredients present in these OTC formulations. As a result, safety cannot be ensured.

Drug interactions

It’s recommended not to drink alcohol while taking melatonin because combining the two substances may cause you to sleep so deeply that your breathing becomes inconsistent, slows, or even stops altogether.

Caffeine should also be avoided since it opposes the effects of melatonin.

Melatonin may have mild to moderate interactions with certain medications and supplements. It’s generally recommended to take it with caution alongside the following:³⁵

  • Warfarin (Jantoven, Coumadin) and other blood thinners like apixaban (Eliquis) and enoxaparin (Lovenox) or antiplatelet medicines like aspirin and clopidogrel (Plavix)

  • Antidepressants like sertraline (Zoloft) and amitriptyline (Elavil)

  • Antipsychotic medications, such as aripiprazole (Abilify) and clozapine (Clozaril)

  • Sedatives like alprazolam (Xanax) and diazepam (Valium)

  • Muscle relaxants, such as cyclobenzaprine (Flexeril, Amrix) and baclofen (Lioresal)

  • Opiates, such as tramadol (Ultram) and meperidine (Demerol)

  • Oral contraceptives

  • Non-steroidal anti-inflammatory medications (NSAIDs) like ibuprofen (Motrin, Advil), ketorolac (Toradol), and others

  • Immune-system-blocking medications, such as those taken after an organ transplant

  • Insomnia medications such as zolpidem (Ambien) and doxylamine (Unisom)

  • Tryptophan supplements for insomnia

  • Blood pressure medications, such as nifedipine (Procardia)

  • Anti-seizure medications like topiramate (Topamax) and phenobarbital (Luminal)

  • Alcohol, marijuana

What to discuss with your doctor before starting melatonin

Before taking melatonin, here’s some important information to discuss with your doctor:

  • The type of sleep issues you’re experiencing

  • Previous medications used to treat your condition and whether they caused any side effects

  • Any current mental and physical health issues

  • Any allergies to medications

  • All other medications you’re currently taking or take occasionally, including blood thinners, other sedatives, OTC products, and herbal and nutritional supplements

  • Your use of alcohol and caffeine

  • Pregnancy, breastfeeding, or plans for pregnancy

  • Any upcoming medical or dental procedures for which you may be prescribed medication

  • Your lifestyle, including type of work, since some side effects of melatonin may prevent you from driving and performing other activities that require you to be alert, such as operating machinery

Stopping melatonin

Always speak to your doctor before you stop taking melatonin or any other dietary supplement or medication.

Although melatonin is not generally considered addictive, your doctor can help ensure that you discontinue your dosing schedule safely and effectively.

Researchers looked at the potential for melatonin withdrawal with the use of prolonged-release formulations. They found that participants did not experience rebound insomnia after discontinuation and identified positive residual effects.³⁶

Tips for taking melatonin

  • Follow the instructions on the label for the appropriate time to take your melatonin supplement. It’s always best to review your situation and make a plan with your doctor before starting on melatonin.

  • Avoid driving, using machinery, riding a bike, or doing activities that require your full attention because melatonin may cause grogginess and a lack of focus.

  • Avoid taking melatonin if you are pregnant, nursing, or planning a pregnancy unless recommended by your doctor.

  • Don’t consume alcohol with melatonin because combining the two may affect your breathing during sleep.

  • Don’t consume caffeine with melatonin since it has the opposite effect.

  • Check with your doctor to see if you are taking other medications or supplements that may interact with melatonin.

  • Look for supplements that are USP-verified to be sure of their quality and that you’re getting the quantity specified.

Frequently asked questions

What does melatonin do?

Melatonin activates certain receptors in the body to regulate mental, physical, and behavioral processes that follow a 24-hour cycle. These are known as circadian rhythms and include sleeping at nighttime and waking in the morning light.

The supplement is often used to help with certain sleeping issues, such as insomnia, jet lag, and sleep disorders experienced by those who work a nontraditional schedule.

What are the negative effects of melatonin?

Along with its benefits, melatonin may cause drowsiness, headaches, dizziness, night sweats, nausea, dry mouth, and skin itchiness.

Children taking melatonin may also experience diarrhea, bed wetting, and an increased risk for seizures if they have a pre-existing neurological disorder.

In rare instances, more severe effects of melatonin may include vertigo, blurry vision, confusion, blood in the urine, feeling down or depressed, and psoriasis.

Is it good to take melatonin daily?

Melatonin may be used daily for short periods. This is something to discuss with your physician.

Some doctors recommend taking it just two or three times per week for a few weeks only.

If your sleep problems persist, you may need a formal medical consultation to get a diagnosis and appropriate treatment.

Who shouldn’t take melatonin?

Talk to your doctor before taking melatonin, particularly if you are pregnant or nursing; have dementia, a seizure disorder, diabetes, depression, glaucoma, liver or kidney disease, an autoimmune disorder, a clotting or bleeding condition, or high or low blood pressure; or are taking blood thinners, other sedatives, or organ transplant medication.

  1. Melatonin | NIH: StatPearls

  2. Melatonin: What You Need To Know | NIH: National Center for Complementary and Integrative Health

  3. Circadian Rhythms | NIH: National Institute of General Medical Sciences

  4. Melatonin Natural Health Products and Supplements: Presence of Serotonin and Significant Variability of Melatonin Content (2017)

  5. Melatonin | NIH: StatPearls

  6. Melatonin for the prevention and treatment of jet lag (2002)

  7. Non-24-Hour Sleep–Wake Rhythm Disorder in the Totally Blind: Diagnosis and Management (2017)

  8. Melatonin: Pharmacology, Functions and Therapeutic Benefits (2017)

  9. Melatonin | MedlinePlus

  10. Melatonin: What You Need To Know | NIH: National Center for Complementary and Integrative Health

  11. Melatonin | NIH: StatPearls

  12. Nanotechnology-based advances in the efficient delivery of melatonin (2022)

  13. Melatonin | NIH: StatPearls

  14. (As above)

  15. Melatonin: What You Need To Know | NIH: National Center for Complementary and Integrative Health

  16. Melatonin for the prevention and treatment of jet lag (2002)

  17. The effectiveness of melatonin for promoting healthy sleep: a rapid evidence assessment of the literature (2014)

  18. Melatonin Treatment for Pediatric Patients with Insomnia: Is There a Place for It? (2022)

  19. (As above)

  20. Melatonin | NIH: StatPearls

  21. Melatonin | MedlinePlus

  22. Clinical Practice Guideline for the Treatment of Intrinsic Circadian Rhythm Sleep-Wake Disorders: Advanced Sleep-Wake Phase Disorder (ASWPD), Delayed Sleep-Wake Phase Disorder (DSWPD), Non-24-Hour Sleep-Wake Rhythm Disorder (N24SWD), and Irregular Sleep-Wake Rhythm Disorder (ISWRD). An Update for 2015 (2015)

  23. The effectiveness of melatonin for promoting healthy sleep: a rapid evidence assessment of the literature (2014)

  24. (As above)

  25. Melatonin Treatment for Pediatric Patients with Insomnia: Is There a Place for It? (2022)

  26. Melatonin | MedlinePlus

  27. Melatonin’s Benefits and Risks as a Therapy for Sleep Disturbances in the Elderly: Current Insights (2022)

  28. Potential Uses and Benefits of Melatonin | Poison Control

  29. Melatonin | NIH: StatPearls

  30. Melatonin: What You Need To Know | NIH: National Center for Complementary and Integrative Health

  31. Melatonin for Insomnia in Medical Inpatients: A Narrative Review (2022)

  32. Sleep, Growth, and Puberty After 2 Years of Prolonged-Release Melatonin in Children With Autism Spectrum Disorder (2021)

  33. Melatonin use during pregnancy and lactation: A scoping review of human studies (2021)

  34. Melatonin | NIH: Drugs and Lactation Database (LactMed®)

  35. Melatonin dosing, indications, interactions, adverse effects, and more. | reference medscape

  36. Prolonged-release melatonin for insomnia – an open-label long-term study of efficacy, safety, and withdrawal (2011)

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Disclaimer

Here at HealthMatch, we’ve done our best to ensure that the information provided in this article is helpful, up to date, and, most importantly, accurate.

However, we can’t replace the one-to-one advice of a qualified medical practitioner or outline all of the possible risks associated with this particular drug and your circumstances.

It is therefore important for you to note that the information contained in this article does not constitute professional medical or healthcare advice, diagnosis or recommendation of treatment and is not intended to, nor should be used to, replace professional medical advice. This article may not always be up to date and is not exhaustive of all of the risks and considerations relevant to this particular drug. In no circumstances should this article be relied upon without independent consideration and confirmation by a qualified medical practitioner.

Your doctor will be able to explain all possible uses, dosages, precautions, interactions with other drugs, and other potential adverse effects, and you should always talk to them about any kind of medication you are taking, thinking about taking or wanting to stop taking.

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