For some people, melatonin may cause headaches, which could be the reason for this reaction. Individuals can have different sensitivities to melatonin and other ingredients in the blend.
What you can do
Try starting with a smaller serving to assess your tolerance
Ensure you’re staying hydrated
Consult a licensed healthcare professional to determine if this product is right for you
If symptoms persist, it’s best to discontinue use and seek medical advice.