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Medically Approved

How much melatonin should I take?

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Is 20 mg of melatonin too much?Recommended dosageSide effectsWhat should you avoid?Summary
Melatonin supplements can help manage sleep problems such as insomnia, but taking the right amount is important. The dosage that is safe for you may not be safe for others.
Medically reviewed by Jennie Olopaade, PharmD, RPH
Written by D. M. Pollock
Updated on December 8, 2023

Melatonin is a naturally occurring hormone that your body makes at nighttime to help you fall asleep.

Your brain triggers the release of melatonin in response to darkness, which helps regulate your circadian rhythm. This is the internal 24-hour body clock that indicates your sleep and wake cycle.

Melatonin is available to buy as a dietary supplement in the form of tablets, liquids, or patches. They typically contain synthetic melatonin, but may contain alternatives from animals or microorganisms.

If you experience any of the following health concerns, melatonin supplements may help manage your symptoms:

  • insomnia (trouble sleeping)
  • pre-surgery anxiety
  • headaches
  • delayed sleep-wake phase disorder
  • jet lag
  • post-traumatic brain injury

Dosages of melatonin will vary depending on your specific needs and what your body can tolerate.

While melatonin supplements are safe and come with minimal risks, overdosing on these supplements can cause serious side effects. It’s important to know how much you should be taking to avoid unpleasant symptoms.

Is 20 mg of melatonin too much?

Man laying awake in bed to depict the question 'how much melatonin should I take?'
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Most capsules of melatonin come in 2-milligram (mg) tablets. This allows you to take small doses at first to see whether you can tolerate it before moving on to higher doses.

Certain factors will affect your tolerance to melatonin supplements, such as:

  • your weight
  • age
  • your general physiological sensitivity

Typically, doses that doctors recommend are between 1 mg and 5 mg. The maximum dose of melatonin you should take is 10 mg once daily, which can be effective for various pain conditions.

Depending on your reason for taking melatonin, a doctor may recommend only taking these supplements 2–3 times per week to see if this has a positive effect.

Melatonin supplements are safe, but healthcare professionals don’t typically recommend taking 20 mg at once.

The maximum recommended dose of 10 mg is usually enough to help ease conditions such as insomnia.

Melatonin supplements are slow release, meaning they gradually take effect during the night.

If you’re an adult with difficulty sleeping or a health condition that prevents you from getting good-quality sleep, a doctor may recommend melatonin supplementation.

It’s best to take melatonin with food. If your supplements are slow release, do not crush or cut them up.

The recommended dose for short-term insomnia in adults is 2 mg, to take 1–2 hours before you go to bed. This dosage typically has an immediate release.

Doctors don’t recommend taking melatonin for more than 4 weeks when dealing with short-term sleep problems.

If you’re still experiencing symptoms after this time, consider speaking with a healthcare professional.

For long-term insomnia, doses may increase to 10 mg per day, to take 30 minutes to 1 hour before you go to bed.

If you’re taking melatonin to help ease jet lag, you can’t take it for longer than 5 days.

You can also take melatonin when flying to avoid jet lag symptoms. The recommended doses are 0.5–2 mg to be taken preflight and 5 mg postflight for up to 4 days.

Side effects of taking too much melatonin

Melatonin is a very safe supplement, which is not known to be life threatening even at doses as high as 800 mg.

But taking more than a doctor recommends can result in side effects such as:

  • drowsiness
  • changes to your eyesight
  • feeling faint
  • unexplainable blood in urine
  • urinary incontinence
  • nightmares
  • dizziness
  • headaches
  • confusion
  • low blood pressure
  • fatigue (low energy)
  • hypothermia
  • rapid heart rate
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What should you not take with melatonin?

Before taking melatonin supplements, it’s important to speak with a doctor, as they can help you understand what you should do. This is especially important if you’re taking other medications.

Melatonin can affect how certain medications work or cause dangerous side effects when it interacts with these substances.

These medications include:

  • Benzodiazepines: Taking melatonin alongside benzodiazepines, such as diazepam (Valium), can increase your risk of melatonin overdose and increase the sedative effects of the benzodiazepine drug.
  • Zolpiem (Ambien): Zolpiem is a medication that can help relieve insomnia. Taking melatonin at the same time can cause extreme drowsiness and increase your chance of strong side effects.
  • Warfarin (Coumadin): There is evidence that melatonin can increase the action of warfarin and cause excess blood thinning. This may increase your chance of life threatening bleeding.
  • Nonsteroidal anti-inflammatory drugs (NSAIDs): NSAIDs can reduce the activity of melatonin, so be careful when taking medications like ibuprofen (Advil) with melatonin, as it may lower the effectiveness of the supplement.
  • Contraceptive pills: Taking melatonin at the same time as contraceptive birth control, such as levonorgestrel and ethinyl estradiol (Tyblume), may increase your likelihood of experiencing melatonin side effects like extreme drowsiness.
  • Antihistamines: First-generation antihistamines are sedatives that often cause drowsiness. Taking melatonin at the same time as one of these medications, like diphenhydramine (Benadryl), can increase your chance of side effects like extreme fatigue.

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20 mg of melatonin is above the standard recommended dose and may cause side effects like severe fatigue. The typically recommended dosage is up to 10 mg.

If you want to try melatonin for symptoms such as insomnia, it’s important to speak with a doctor first.

This is to ensure you’re not at risk of any harmful drug interactions, as other medications can increase the side effects of melatonin.  

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