Alcohol can cause headache in two ways – either while you’re drinking, or as a delayed effect (a hangover). The headache normally has a pulsating quality and is aggravated by physical activity. There are a number of reasons why alcohol causes headache – it dilates blood vessels, causes dehydration, and produces irritating breakdown substances, all of which can trigger headache and the associated hangover symptoms. Secondary alcohol headache should also be differentiated from migraine triggered by alcohol consumption. This headache type will resolve spontaneously within 72 hours.
Headache attributed to a substance or its withdrawal – read more about other substances that may cause headache in the International Classification of Headache Disorders (ICHD-3)