Taking too much melatonin can lead to an overdose, though it is generally considered one of the least toxic medications. Symptoms of melatonin overdose commonly include drowsiness, dizziness, fatigue, headache, confusion, nightmares, hypotension (low blood pressure), tachycardia (fast heart rate), and hypothermia (low body temperature)
. More specific signs of melatonin overdose can include:
- Excessive sleepiness or grogginess during the day
- Persistent nausea and vomiting
- Stomach pain or cramps
- Irritability, anxiety, or mood changes including short-term depression symptoms
- Dizziness and headaches
- Diarrhea and sudden joint pain
- Changes in blood pressure, sometimes hypotension
- Trouble breathing or slurred speech in severe cases, which require emergency medical attention
While melatonin overdose is rarely life-threatening, severe symptoms such as difficulty breathing, seizures, loss of consciousness, or very high blood pressure (180/120 mm Hg or higher) warrant immediate emergency care
. In children, melatonin poisoning has increased, with signs including extreme sleepiness, repeated vomiting, and slurred speech, which may require emergency evaluation
. Treatment for overdose is mainly supportive, involving monitoring vital signs and managing symptoms. Gastric lavage and activated charcoal have been used in clinical cases of large ingestion, followed by observation and psychiatric consultation if the overdose was intentional
. Because melatonin supplements are not tightly regulated, dosages on labels may be inaccurate, and effects vary by individual factors such as age, weight, sensitivity, and concurrent medications. Recommended doses for adults generally range from 1 to 5 mg, with doses above 10 mg potentially causing more side effects. Starting with a low dose and consulting a healthcare provider before use is advised
. In summary, taking too much melatonin can cause unpleasant side effects mostly related to excessive sedation and gastrointestinal discomfort, with rare but serious symptoms requiring urgent care. Careful dosing and medical guidance help minimize risks associated with melatonin supplementation.
