Alcohol is a huge dehydrator – it interferes with the brain and kidney communication making you wee more, which can lead to dehydration.
Source: 6 Reasons to Drink Water @ WebMD
- Dehydration – Causes @ NHS Choices
Excerpt: Dehydration can also occur as a result of drinking too much alcohol. Alcohol is a diuretic, which means that it makes you pee more.