What are the side effects of Natrol?

You took your Natrol melatonin at 10 p.m., slept through the night, and still woke up feeling like your head was packed with cotton.

That morning fog is melatonin's most commonly reported side effect, whichever brand you buy. In a review of 37 placebo-controlled trials, daytime sleepiness topped the list, ahead of headache and dizziness.

So what are the side effects of Natrol? Mostly melatonin's own, shaped by three things: the dose you take, the format it comes in, and whatever else is in the bottle. Here's what the research and Natrol's own labels say.

Table of Contents

• 1. What Are the Side Effects of Natrol? It Depends Which Natrol
• 2. The Side Effects That Come From Melatonin Itself
• 3. Dose: Where to Look First
• 4. Time-Release, Gummies and the Label-Accuracy Question
• 5. What Else Is in the Bottle
• 6. When to Check With a Doctor First
• 7. Controlling Your Dose: What a Liposomal Liquid Adds
• Frequently Asked Questions
• Conclusion
• Research References

1. What Are the Side Effects of Natrol? It Depends Which Natrol

Natrol is a brand, not an ingredient, and not every Natrol product contains melatonin. Drugs.com's side-effect page for Natrol SAMe, for example, warns against taking it with antidepressants or within 14 days of using an MAO inhibitor. None of that is a melatonin warning, so start by checking which Natrol product you have.

If your label says melatonin, this guide is for you. Natrol sells adult melatonin in several forms, including standard, fast-dissolve and time-release tablets, regular and time-release gummies, sleep blends with added ingredients, and a berry-flavoured liquid measured by dropper. Natrol's label for that liquid, recorded in the NIH's Dietary Supplement Label Database, warns that melatonin may cause drowsiness and cautions against driving, operating machinery or drinking alcohol after taking it.

The same label describes melatonin as an occasional, short-term aid, and it asks you to talk to a doctor first if you're under 18, take any medication, are pregnant or breastfeeding, or have an autoimmune condition or depressive disorder. Natrol's own FAQ puts the risk plainly: most people notice no side effects, and some notice mild drowsiness or vivid dreams. Its Fast Dissolve directions say to take 1 tablet 30 minutes before bedtime.

2. The Side Effects That Come From Melatonin Itself

Whatever the brand, the core side effects come from the hormone. A useful tally comes from a review of 37 placebo-controlled trials that used between 0.15 mg and 12 mg a day. These were the side effects reported most often:

• Daytime sleepiness: 1.66%
• Headache: 0.74%
• Dizziness: 0.74%
• Lower body temperature (hypothermia): 0.62%

Most of those side effects faded within a few days, or as soon as people stopped taking melatonin, and the reviewers found nothing life-threatening; rarer effects such as agitation, mood swings, nightmares and palpitations showed up in very few reports. A second review of 50 controlled studies found that 26 reported no statistically significant side effects at all, while the rest turned up mostly minor, short-lived effects such as fatigue, mood changes or slower reactions. A handful involved blood pressure, heart rate or blood sugar, effects that seemed to depend on dose, timing and interactions with blood-pressure drugs.

That points to 2 practical levers, timing and dose: the second review's authors concluded that most side effects can likely be avoided or managed by timing doses to match your natural body clock, and dose is covered next. One honest caveat: most of the 37 trials in the first review lasted 4 weeks or less, so the research says much less about years of nightly use. Our melatonin side effects and safety guide covers the longer-term picture, and our complete guide to melatonin for sleep explains how the hormone works.

3. Dose: Where to Look First

If a Natrol product is giving you side effects, look at the dose before you blame the brand. In a 2022 review of trials using 10 mg or more, drowsiness, headache and dizziness appeared about 40% more likely than with a placebo. Serious side effects didn't increase, but just 4 of the 79 trials were rigorous enough to pool, so read that 40% as a warning sign rather than a settled figure.

High strength is easy to find on the shelf: Natrol sells some of its melatonin as Advanced Max Strength time-release tablets. Smaller doses can work, though. In an MIT trial of adults over 50, 0.3 mg restored sleep. A dose ten times larger, 3 mg, also improved sleep, but it lowered body temperature and kept melatonin in the blood into the daylight hours.

If side effects are bothering you, try these 3 changes, one at a time:

• Drop the strength. In the MIT trial, 0.3 mg was enough to restore sleep, and our melatonin dosage guide explains how to find your own starting point.
• Follow the label timing. Natrol's Fast Dissolve directions say 30 minutes before bedtime, and a dose taken later in the night can leave less time for it to wear off before morning.
• Go carefully at 10 mg and above. That's the range where common side effects appeared about 40% more likely.

4. Time-Release, Gummies and the Label-Accuracy Question

Natrol says its time-release gummies release melatonin gradually through the night to help you stay asleep. That can suit people who wake at 3 a.m., but it also stretches melatonin's effect later into the night, and we found no study measuring next-day grogginess from time-release supplements specifically. The same page says the gummies aren't intended for anyone under 18, that Natrol tests every batch and uses independent labs, and that the gummies are made with extra melatonin so they still meet label strength by the expiry date.

Gummies raise a separate question: how much melatonin you're actually getting. A JAMA analysis of 25 melatonin gummies found 22 (88%) didn't match their labels, with actual melatonin ranging from 74% to 347% of the amount stated.

Other formats aren't immune. A 2017 study of 31 melatonin supplements in several forms found content from 83% below to 478% above the label, with up to 465% variation between batches of the same product, and 26% contained serotonin that wasn't listed. Both studies sampled products across the market, so they describe a risk for the whole category, not a verdict on any one brand, which is why batch testing and a certificate of analysis are worth asking any brand about.

5. What Else Is in the Bottle

The melatonin is just one part of what you're taking. Natrol's Fast Dissolve tablets list xylitol, a sugar alcohol, first among their other ingredients, and they also contain soy polysaccharides, which matters if you have a soy allergy. Xylitol is common in products made for people, including chewable vitamins and other supplements, but it can poison dogs: the FDA warns that a dog's blood sugar can crash within 10 to 60 minutes of eating it. Check the label on any supplement you keep at home, and keep every bottle well out of your pet's reach.

Combination products bring their own profiles too. Natrol's Sleep + Restore gummies pair melatonin with GABA, magnesium, vitamin B6 and 3 botanicals (tart cherry, lemon balm and chamomile), and the label adds cautions for kidney disease and for anyone already taking other magnesium products. If a blend doesn't agree with you, try plain melatonin before deciding melatonin is the problem, because any of those 3 botanicals or other added ingredients could be the culprit instead.

6. When to Check With a Doctor First

Melatonin can interact with several kinds of medicine. Mayo Clinic lists 7 groups: blood thinners, seizure medicines, birth control, blood pressure medicines, diabetes medicines, immunosuppressants and drugs broken down by the liver. Natrol's own label asks anyone taking medication, pregnant or breastfeeding, or living with an autoimmune condition or depressive disorder to talk to a doctor first, and our melatonin drug interactions guide walks through the main combinations.

Older adults have their own reasons to start low. Mayo Clinic lists a raised risk of falls and confusion among melatonin's less common side effects, and in the MIT trial of adults over 50, the 3 mg dose lowered body temperature while 0.3 mg was enough to restore sleep. Our guide to melatonin side effects in older adults goes further.

Children need extra care. US poison centres received 260,435 reports of children and teens swallowing melatonin between 2012 and 2021, the yearly number rose 530%, and hospitalizations climbed too, mostly from accidental swallowing by children aged 5 and under. Natrol's adult labels advise a doctor's check for anyone under 18, and several say the product isn't intended for that age group at all, so keep every bottle, especially gummies, out of children's reach and talk to a pediatrician before giving a child melatonin.

7. Controlling Your Dose: What a Liposomal Liquid Adds

If your side effects trace back to dose, a useful feature to look for in any melatonin product is control over how much you take. The research above points the same way: common side effects appeared to rise at 10 mg and above, and in the MIT trial a dose one-tenth the size did the job. A liquid measured by dropper lets you take less without splitting a tablet, and Natrol's own liquid works that way too.

Bio Absorb Nutraceuticals makes Liposomal Liquid Melatonin 5mg, a sublingual liquid you hold under your tongue before swallowing, with the melatonin encapsulated in phospholipid spheres called liposomes. It's made in Canada in a GMP-certified facility and third-party tested every batch, with a certificate of analysis available on request. It's non-GMO, gluten-free, nut-free, dairy-free (vegan) and corn-free, and backed by a 100% money-back guarantee. See current pricing and serving details.

To be clear about the limits: no published trial has compared our liquid with Natrol's products head to head, so we can't promise fewer side effects, and it may not suit you. What differs is the format, which we compare side by side in Natrol vs liposomal melatonin, and if you'd rather weigh several brands, our guide to alternatives to Natrol melatonin covers the options. If you're following the start-low advice, Bio Absorb also lists Liposomal Liquid Melatonin 1.5mg.

Frequently Asked Questions

Why do I feel groggy the morning after taking Natrol?

Start with the dose. In an MIT trial, 3 mg kept melatonin in the blood into the daytime, while 0.3 mg restored sleep, so a lower strength taken at the label time is worth trying. Our guide to whether melatonin makes it hard to wake up covers other causes.

Can Natrol melatonin cause vivid dreams or nightmares?

Yes, and Natrol's own FAQ lists vivid dreams as a possible mild effect. In a review of 37 clinical trials, nightmares were among the few side effects considered clinically notable, and most side effects faded within days or after stopping. If dreams are disrupting your sleep, try a lower dose first.

Is it safe to take Natrol melatonin every night?

Natrol's label describes its melatonin as an occasional, short-term aid, and most clinical trials have lasted weeks, not years. Short courses look well tolerated in the research, but if you need melatonin most nights for longer, talk to your doctor. Our article on melatonin tolerance and long-term use looks at what's known.

Can children take Natrol melatonin?

Natrol does sell a Kids melatonin line, marketed for ages 4 and up, but its adult melatonin labels ask for a doctor's advice for anyone under 18, and several say the products aren't intended for that age group at all. Natrol's own FAQ says to talk to your child's doctor first, so check with a pediatrician before giving any child melatonin, and store bottles, especially gummies, where children can't reach them.

Can I take Natrol with antidepressants or blood thinners?

Check with your doctor or pharmacist first. Natrol's melatonin label asks anyone with a depressive disorder or taking medication to consult a physician, Mayo Clinic lists blood thinners among the medicines melatonin can interact with, and if your Natrol product is SAMe rather than melatonin, its antidepressant warning is stricter still. Our melatonin drug interactions guide covers the details.

What should I do if my dog eats Natrol Fast Dissolve tablets?

Call your vet, an emergency clinic or an animal poison control centre right away. The tablets list xylitol among their ingredients, and because serious effects in dogs can be delayed, your dog may need monitoring even if it seems fine at first.

Conclusion

So what are the side effects of Natrol? Mostly melatonin's own, led by sleepiness, headache and dizziness, which appeared about 40% more likely at 10 mg and above, plus whatever the format and added ingredients bring. Start with the lowest strength that works, read the whole label, and if you'd like a liquid you can adjust by the dropper, see current pricing and serving details for Bio Absorb's Liposomal Liquid Melatonin 5mg.

Research References

1. Adverse Events Associated with Melatonin for the Treatment of Primary or Secondary Sleep Disorders: A Systematic Review. CNS Drugs, Vol. 33 (2019). Across 37 placebo-controlled trials, daytime sleepiness, headache and dizziness were reported most often, and most side effects resolved within days.
2. Adverse events associated with oral administration of melatonin: A critical systematic review of clinical evidence. Complementary Therapies in Medicine, Vol. 42 (2019). Of 50 controlled studies, 26 found no statistically significant side effects, and most reported events were minor.
3. Safety of higher doses of melatonin in adults: a systematic review and meta-analysis. Journal of Pineal Research, Vol. 72 (2022). At 10 mg or more, drowsiness, headache and dizziness appeared about 40% more likely than with placebo, with no detectable rise in serious events.
4. Melatonin treatment for age-related insomnia. Journal of Clinical Endocrinology & Metabolism, Vol. 86 (2001). In adults over 50 with insomnia, 0.3 mg restored sleep; 3 mg also improved sleep but lowered body temperature and kept melatonin elevated into the daytime.
5. Quantity of Melatonin and CBD in Melatonin Gummies Sold in the US. JAMA, Vol. 329 (2023). 22 of 25 melatonin gummy products were inaccurately labelled, at 74% to 347% of the stated amount.
6. Melatonin Natural Health Products and Supplements: Presence of Serotonin and Significant Variability of Melatonin Content. Journal of Clinical Sleep Medicine, Vol. 13 (2017). Melatonin in 31 supplements ranged from 83% below to 478% above label, and 26% contained serotonin.
7. Pediatric Melatonin Ingestions — United States, 2012–2021. Centers for Disease Control and Prevention, MMWR Vol. 71 (2022). US poison centres recorded 260,435 pediatric melatonin ingestions, with the annual number up 530%.
8. Melatonin side effects: What are the risks? Mayo Clinic (accessed September 2026). Common and less common side effects, a 5-hour no-driving window and 7 groups of interacting medicines.
9. Natrol Liquid Melatonin: label record. NIH Office of Dietary Supplements, Dietary Supplement Label Database (2025). Natrol's label warnings on drowsiness, short-term use and who needs a physician's advice first.
10. Paws Off Xylitol; It's Dangerous for Dogs. U.S. Food and Drug Administration (2025). In dogs, xylitol can cause a sharp drop in blood sugar within 10 to 60 minutes.
11. Natrol SAMe Side Effects. Drugs.com (accessed September 2026). A non-melatonin Natrol product with its own warnings, including against use with antidepressants.
12. Melatonin Fast Dissolve Strawberry Tablets. Natrol (accessed September 2026). Label ingredients, including xylitol and soy polysaccharides, directions, and Natrol's FAQ on side effects and children's use.
13. Melatonin Gummies Time Release. Natrol (accessed September 2026). Natrol's description of time-release delivery, batch testing and its disclosed overage.
14. Melatonin Advanced Max Strength Time Release Tablets. Natrol (accessed September 2026). Natrol's maximum-strength time-release tablet and its label warnings.
15. Sleep + Restore Gummies. Natrol (accessed September 2026). A combination formula with GABA, magnesium, vitamin B6 and three botanicals, plus its label cautions.

About the Author

David Kimbell is a health writer, digital entrepreneur and former aerospace engineer, based in Ottawa, Canada. He loves translating complex science into clear, actionable guidance for consumers seeking evidence-based solutions.

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Important Disclaimers

Medical Disclaimer: This article provides educational information only and is not intended as medical advice. Always consult with a qualified healthcare provider before starting any new supplement, especially if you have existing health conditions, take medications, or are pregnant or nursing.

FDA/Health Canada Statement: These statements have not been evaluated by the Food and Drug Administration or Health Canada. This product is not intended to diagnose, treat, cure, or prevent any disease.