Alcohol consumption can have several ill effects: 1. It slows down brain activity and nervous system function, impairing judgment and reaction time. This increases the risk of road accidents from drunken driving. 2. It lowers inhibitions, making drunk people more quarrelsome. This leads to increased violence and crime. 3. Heavy drinking on a single occasion can cause staggered movement, slurred speech, blurred vision, dizziness, and vomiting. Drinking large quantities can make a person pass out.