Side Effects of a Melatonin Overdose

Melatonin supplements are a synthetic version of the naturally occurring hormone melatonin, which helps regulate your body's sleep-wake cycle. Taking appropriate doses of melatonin may help alleviate issues associated with sleeping problems, such as insomnia and jet lag, according to MedlinePlus. Before taking this supplement, discuss the side effects of a melatonin overdose with your medical provider.

A melatonin overdose may cause severe drowsiness.


Severe drowsiness may occur if you take an unusually large dose of melatonin, warns. This supplement is typically used to induce sleep and may affect your ability to remain attentive or focused during your daily activities. Excessive drowsiness may cause you to fall asleep shortly after treatment and you may remain asleep for several hours.

Upset Stomach

High doses of melatonin may irritate your digestive tract. Consequently, you may experience stomach irritation, nausea or vomiting following an overdose of melatonin. These side effects may also contribute to a decrease in your normal appetite. Consult a doctor as soon as possible if you experience severe stomach discomfort or persistent vomiting after taking melatonin.


Headache pain may arise following an overdose of this supplement. This side effect may interfere with your ability to focus on daily tasks and can exacerbate sensations of drowsiness or fatigue. If you develop sudden or severe headache pain after taking melatonin, seek care from your primary medical provider.

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