Why do smoothies give you a headache?

Smoothies can cause headaches for several reasons. One common culprit is the sugar content, especially if they contain high amounts of fruit or added sweeteners, which can lead to blood sugar spikes followed by crashes. Additionally, if you consume a smoothie too quickly, the rapid intake of cold liquids can trigger a "brain freeze" headache. Dehydration or ingredient sensitivities, such as lactose or certain fruits, can also contribute to headache symptoms.