Alcohol makes you throw up primarily because vomiting is a protective reflex to expel toxins from the stomach. When alcohol enters the body, it is metabolized by the liver into acetaldehyde, a toxic substance. If acetaldehyde accumulates faster than the liver can process it, the body triggers vomiting to get rid of the excess toxin. Additionally, alcohol irritates the stomach lining and causes increased acid production, which can inflame the stomach (gastritis) and make you feel nauseous, also leading to vomiting. Alcohol also slows down digestion, causing proteins in the stomach to rot and produce toxic substances that can trigger vomiting. Moreover, excessive drinking can cause the pyloric valve to relax, allowing bile reflux into the stomach, which further irritates it and induces vomiting. Thus, throwing up after drinking is the body's way of protecting itself from alcohol toxicity and stomach irritation.