Alcohol withdrawal is not a clear-cut process. It can vary widely from person to person based on the severity of their drinking habits, and get very messy in the interim before the body re-adjusts to functioning without alcohol. Therefore, alcohol withdrawal-induced headaches can be difficult to predict. The average withdrawal process can take a few days or, in rare cases, over a month to pass. Alcohol withdrawal symptoms can occur within hours after your last drink. However, the time distinction is not as important as the severity of the symptoms and does not follow a linear time-based schedule. Minor, moderate, or severe symptoms of withdrawal can occur at the very onset of the withdrawal process.