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Can You Overdose on Melatonin? How to Determine the Right Dosage

Note: The U.S. Food and Drug Administration (FDA) does not approve supplements for safety and effectiveness. Talk to a healthcare professional about whether a supplement is the right fit for your individual health, and about any potential drug interactions or safety concerns.

Some people take the over-the-counter (OTC) supplement melatonin to help them fall asleep. But it's actually possible to get too much melatonin, which can cause negative side effects.

As an over-the-counter supplement, melatonin also is not regulated by the U.S. Food and Drug Administration (FDA), so the amount of melatonin actually in a supplement may vary from what is listed.

In addition to speaking with your healthcare professional about melatonin, it's vital to know that you are using melatonin safely and what it looks like when you are not.

Melatonin overdoses leading to severe toxicity and life-threatening symptoms are rare at any dose, says Glenna S. Brewster Glasgow, PhD, RN, assistant professor at Emory University's Nell Hodgson Woodruff School of Nursing in Atlanta.

“Taking high doses can still cause unwanted side effects and disrupt natural sleep patterns,” Dr. Brewster Glasgow says.

While serious side effects are less common with melatonin compared with certain other sleep aids, you may experience substantial side effects if you overdose.

 They may differ for children and adults, Brewster Glasgow says.

“In children, melatonin overdose tends to present with milder symptoms compared with adults,” she says, “though the effects can last longer due to their smaller body size and slower metabolism.”

Brewster Glasgow says that signs of a melatonin overdose may include:

  • Severe drowsiness or prolonged sedation
  • Confusion, disorientation, and cognitive impairment
  • Vertigo or loss of coordination
  • Agitation or irritability
  • Slurred speech and tremors
  • Psychotic effects such as hallucinations and nightmares, which are rare
Typical melatonin side effects include:

  • Headache
  • Dizziness
  • Nausea
  • Drowsiness
Less common side effects may include:

  • Short-term depression
  • Low-level anxiety
  • Stomach cramps
  • Low blood pressure
  • Lower levels of alertness
  • Seizures, in children

“These mild symptoms usually subside after adjusting the dosage,” Brewster Glasgow says. “If you experience more severe symptoms, it is advisable to contact your healthcare provider.”

Although vivid dreams also can occur as melatonin side effects, they are not always signs of a melatonin overdose.

 Melatonin can increase rapid eye movement (REM) sleep — the sleep stage in which you dream the most — so your brain's natural response may be to produce more dreams.

Taking a low dose of melatonin for one to two months is considered safe for most healthy adults.

 But knowing what a low dose is can be tricky.
There is no officially recommended dosage for melatonin, but experts suggest adults start at 1 milligram (mg) and increase gradually, not to exceed 10 mg.

Some melatonin brands may recommend a dosage that's more than your body needs. Research also suggests that as much as 90 percent of melatonin products contain an amount different than what is labeled, sometimes containing as much as 3 times the advertised amount.

 For this reason, finding a reputable melatonin brand is essential if you want to try it.

A US Pharmacopeia (USP) logo on a product indicates that it has been independently verified that it contains the dosage it claims, does not contain harmful levels of contaminants, and has been manufactured according to the FDA's Good Manufacturing Practices.

A healthcare provider can help determine if melatonin is appropriate for your situation and guide you on the correct dosage.

Where to Start When Choosing a Melatonin Dosage

Most people produce enough melatonin in their body to sleep well. If you need a little extra melatonin to reset your sleep cycle, you probably don't need more than 3 mg, research suggests.

 Some people sleep better with as little as 0.3 mg.

Melatonin needs vary from person to person. A low dose can be just as effective as a higher dose, especially in people who are highly sensitive to melatonin.

It's best to increase your dose until you find an amount that improves sleep without causing side effects.

 Daytime drowsiness doesn't typically occur with melatonin, but it can happen if you take too much melatonin the night before.

The American Academy of Sleep Medicine recommends that parents consult with physicians before giving a melatonin supplement to a child.

Likewise, if you are pregnant or breastfeeding, talk to your doctor before trying melatonin, as there is not enough research about the potential side effects of melatonin supplements related to pregnancy. Doctors may only recommend melatonin to people with specific health problems or characteristics linked to low melatonin, such being pregnant and having preeclampsia.

Knowing how other medicines interact with melatonin may prevent uncomfortable or even dangerous effects on your health. As a rule of thumb, consult your doctor before taking any new supplements.

Melatonin can reduce the effectiveness of some prescription drugs, triggering possibly serious complications. Medication that may interact with melatonin include:

  • Anticoagulants Melatonin can increase the risk of bleeding in people who take medications to reduce blood clotting.
  • Blood Pressure Medications Melatonin may increase blood pressure in people who take medication to control their hypertension.
  • Anticonvulsants Melatonin supplements may block the effects of these medications and increase how many seizures occur in people who take them. This effect can be particularly pronounced in children with brain and nervous-system disabilities.
  • Contraceptives People who use contraceptives may experience extra sleepiness if they take melatonin.

     These medications also increase melatonin levels, so supplementing melatonin can push levels above a healthy threshold.
  • Immunosuppressants Because melatonin may increase immune-system activity, it may reduce the effectiveness of medications that limit immune-system function.
  • Steroids Melatonin boosts the immune system, which steroids are actively trying to control, and may lessen steroids' effect.
  • Diabetes Medications Melatonin can affect blood glucose levels, which diabetes medications aim to control.
  • CNS Depressants If you use a central nervous system (CNS) depressant, such alprazolam (Xanax) or diazepam (Valium), melatonin may cause extra drowsiness.

  • Selective Serotonin Reuptake Inhibitors (SSRIs) Melatonin has reduced the depression-treating effects of SSRIs such as fluoxetine and desipramine in animal studies, although more research is necessary to confirm similar effects in humans.

  • Fluvoxamine (Luvox) This SSRI significantly increases melatonin levels by inhibiting its metabolism, potentially leading to more potent effects or increased side effects, Brewster Glasgow says.

  • Ritlecitinib (Litfulo) Used to treat alopecia, this drug may increase melatonin metabolism and reduce its effectiveness, Brewster Glasgow says.

  • Viloxazine (Qelbree) This selective norepinephrine reuptake inhibitor (SNRI) is an ADHD treatment.

     Brewster Glasgow advises against taking melatonin while on this medication because of unpredictable interactions.
You should avoid taking melatonin if you have a diagnosis for an autoimmune disease, such as lupus. Autoimmune diseases result from an overactive immune system, and inflammation is a common effect of these diseases. Melatonin can stimulate immune-system activity, increasing inflammation and worsening an existing disease.

Serious melatonin side effects are rare. In the case of a severe overdose or side effect, speak to a doctor as soon as you can. Symptoms that require medical attention include:

  • Blurry vision or other eyesight changes
  • Feeling faint
  • Confusion
  • Dizziness
  • Vertigo
  • Bleeding that doesn't stop
  • Blood in the urine
  • Bruises you can't explain or don't remember getting

You can speak to Poison Control by phone 800-222-1222 or online at PoisonHelp.

Symptoms that require immediate medical attention include changes to breathing and an inability to wake up fully after taking melatonin. Call 911 or visit the nearest emergency room if these symptoms occur.

“Most people do not need medical assistance after a melatonin overdose, but if there is difficulty breathing, or lethargy, or just if anyone is concerned, I would recommend going to the emergency room,” says Kacey West, PharmD, associate professor of pharmacy practice at Butler University's College of Pharmacy and Health Sciences in Indianapolis.

A low dose can be safe for a child. The American Academy of Pediatrics (AAP) advises that even though no specific guidelines recommend a dosage for children, kids may see helpful effects on sleep after taking 0.5 to 1 mg of melatonin around 30 to 90 minutes before sleep.

Not a lot of research is available in this area, however. It is crucial to speak with your child's doctor because of potential risks.

Brewster Glasgow advises that the main risks of melatonin in children include drowsiness, low alertness, and a slower metabolism.

“Although severe toxicity is rare, children may be at higher risk due to accidental ingestion, especially with flavored or gummy formulations (of melatonin) that appeal to young children,” she says.

Melatonin has become the most reported ingested substance among children to poison control centers.

 According to the National Poison Data System, about 1.7 percent of calls were for children with severe symptoms. While the risks exist, most children experienced mild or no symptoms and felt better after home care.

The Centers for Disease Control and Prevention also reported that 11,000 ER visits in the United States between 2019 and 2022 occurred because of children finding and eating melatonin without supervision, often in the form of gummies.

West adds that although accidental melatonin ingestion or overdose by children can be manageable at home, symptoms such as severe drowsiness or breathing difficulties warrant medical attention.

Vomiting and excessive sleepiness that affect daytime activities are also hallmark symptoms of melatonin poisoning in children. Likewise, if a child's speech is slurred for any reason, visit the emergency room.

For children who have trouble sleeping, the AAP recommends a consistent bedtime routine and avoiding screen exposure an hour before bedtime.

  • Melatonin itself is a naturally produced hormone that plays a large role in telling our body when to stay awake and when it's time to sleep.
  • It is possible to overdose on melatonin and for it to have negative interactions with other medication.
  • Common symptoms of melatonin overdose include nausea, dizziness, drowsiness, and headaches. Symptoms that require emergency attention include breathlessness, loss of consciousness, and vision changes.
  • When taking melatonin, start with the lowest dosage and slowly build up to a helpful amount. Speak to your doctor about ideal dosage and which supplement brands are reputable.

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