Melatonin. Recommended dose up to 10mg. Toxicity occurs if dose exceeds 20mg.
Melatonin Overdose. Above 10mg is above recommended doseage. A serious melatonin overdose in an adult is usually between 20-50mg. A melatonin overdose could lead to symptoms like marked sedation, headache, nausea, vomiting, upset stomach, low blood pressure, dizziness, confusion, disorientation, tremor, liver problems, weakness & seizures.