Ethanol's diuretic effects can also quickly dehydrate you, and a headache is just one of many symptoms of dehydration. In your bloodstream, ethanol can cause headaches through vasodilation. This means that it makes your blood vessels expand. Vasodilation can stimulate certain brain nerves and result in pain.
dizziness explanation: alcohol can cause your blood sugar to fall. if your blood sugar dips too low, you may experience fatigue, weakness, shakiness, or dizziness.
