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.

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.

“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

• Headache
• Dizziness
• Nausea
• Drowsiness

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

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“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.”

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

• 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.

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   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.

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• 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.

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• 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.

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

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

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   Brewster Glasgow advises against taking melatonin while on this medication because of unpredictable interactions.

• 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.

“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.

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.

“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.

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.

• 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.