Tetley Peach Ginger & Dandelion Tea with Vitamin B6

This tea gives me an instant, severe headache.
Curious about the ingredient that might be the culprit, any ideas?

• White hibiscus
• Orange leaves
• Dandelion leaves & root
• Ginger root
• Hibiscus
• Natural flavours
• Sweet blackberry leaves
• Peach juice granules (maltodextrin, peach juice concentrate)
• Vitamin B6 [1, 2]