Melatonin Side Effects

You’ve probably heard of melatonin and seen it on the shelves of pharmacies, health food stores, and even grocery stores. It’s true that melatonin is naturally produced in our bodies, but just like any supplement we take, there is a chance it may have side effects.

Melatonin chemical formula

Melatonin is a hormone produced by the pea-sized pineal gland in our brains and is known to help regulate our sleep-wake cycles. Our sleep-wakes cycles (circadian rhythm) are directly related to darkness and light.

When exposed to light, the pineal gland suppresses the release of melatonin. These levels are minimal during the daytime and rise in the evening, making us feel drowsy and preparing us for sleep.

Background on Melatonin and Why it Could Cause Side Effects

Some factors, such as age, shift work, jet lag, or lifestyle habits may actually keep your body from producing enough melatonin. The inability to produce enough of this sleep hormone can give you trouble trying to get to sleep at night.

If you have trouble sleeping, you may be considering trying an over-the-counter melatonin supplement, and are probably wondering what it is and if it has any side effects.

Melatonin supplements come in different forms such as chewable tablets, pills, and liquids.

There are two different types of melatonin supplements, natural and synthetic. While the natural form of melatonin may sound like a better option, some say that since this type of melatonin comes from the pineal gland of animals, there is a risk of viruses. The synthetic form is man-made and is made to have the same chemical structure as natural melatonin.

There are some studies that show that taking melatonin is safe when taken short-term and that adverse effects are minimal when taken long-term. (1)

It’s also important to note that while melatonin by its self may be safe, it could interfere with other medications and may not be safe to take for those with certain medical conditions.

These adverse effects of melatonin include:

  • Daytime sleepiness
  • Dizziness
  • Headaches
  • Nausea
  • Irritability
  • A “hangover-like” feeling the next day (2)

Other melatonin side effects that have been reported include:

  • Feelings of depression while taking melatonin
  • Worsening of bleeding in those with bleeding disorders
  • Increased blood pressure in those who are taking certain blood pressure medications
  • May increase the risk for seizures in those with a seizure disorder

Melatonin Safety for Kids

There is not much evidence to determine the long-term safety of melatonin in children and adolescents.(3) There are also no human studies done on the safety of melatonin in women that are pregnant or breastfeeding, so it’s best to avoid it altogether if you’re in these categories.

Is it Safe to Take Melatonin Daily?

There are no known dangers of taking melatonin daily.  There is little-no data published on long term melatonin use. (4)

If you decide that a supplement isn’t right for you, there are other ways to try and boost your melatonin production naturally. Some things you can try include eating a healthy diet, reducing blue light exposure 2-3 hours before bedtime, getting sunlight during the day, and avoiding the use of lights if you wake up during the night.

If you are considering adding a melatonin supplement to your routine, make sure you discuss it with your doctor first, especially if you have any medical conditions or are taking medication.

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10 thoughts on “Melatonin Side Effects


    CRAIG [email protected] 17th MAY 22

    I have been taking Melatonin for 6 months as prescribed by my doctor . I take it at 9.30
    pm and by 10.30pm I am asleep .

    I wake in the morning with a hangover which consists of a slight headache as
    well and a dull brain feeling . After a cup of tea I start to feel better but I haven’t trained for 6 months which is starting to get me down due to a lazy feeling and this is getting me down .

  2. Gabe Reply

    I’m 51, just took it for the first time to try and recover from a few days of little sleep. I slept for over 9 hours, but woke up feeling like I had a hangover… pressure in my head, slight headache, and hazy. I’ve been up for five hours and the feeling is still there. I won’t be taking it again.

  3. Freeda Pain Reply

    I was taking the melatonin chewies (2) nightly. It did help with sleep but after several weeks, vision was not great and I became exhausted all the time. Then my pulse went from being normal to just 48 bps. Work or exercise had no effect on pulse rate. I stopped taking melatonin and switched to Benadryl. In a couple days, everything was back to normal. Be careful taking this stuff long term.

  4. Elena musk Reply

    I took it and had a horrible throbbing in my ears called pilistine tinnitus it stopped when I stopped it and my heart was flipping around from it and very sad any one else had strange effects

  5. Lex Reply

    My Granddaughter has been taking 6 mg of Melatonin nightly Sunday – Thursday since she was 5 years old, she will soon be 12. Her doctor did suggest Melatonin as the over counter brand and at 5 mg.

    It does help her sleep but some mornings she says she is still sleepy before going to school, it gets better as the day goes on.

    She doesn’t take it on Friday or Saturday, time off for school holiday breaks and summer vacation.

  6. Jane Reply

    I take 10 mg of Melatonin with “Cyclosome Technology” a sustained released product. that helps to increased my sleep hours. My sleep doctor also suggested I take 75 mg of Amitriptyline at night. I have been taking a low dose of Amitriptyline-(25 mg 2x/day), for years to prevent daily headache. I now take it as directed and it definitely helps maintain sleep, as I now sleep 7-8 hrs/night.

  7. Bob Reply

    I am a 69 year old man who has been taking up to 20 mg of melatonin for years.

    I have been feeling anxious and depressed lately, with a lack of energy, symptoms that I associated with the incredibly dismal state of affairs in our society.

    Last night I skipped taking the melatonin. This morning I woke up around 3 AM and could not get back to sleep. Today I realize my eyesight has improved remarkably.

    I had been associating my poor vision to dryness and age. I had been having trouble focusing on objects up close. Today my eyesight is sharp and clear.

    I also feel less depressed and tired. Getting my vision back is huge.

  8. Rick Rosato Reply

    I have been taking Melatonin 10 mg for some time now and I find I am always tired all day long. I think they help with my sleeping at bedtime but don’t last all night long and want to know if having effect from this Med?

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