Caffeine withdrawal occurs when a person who regularly consumes caffeine suddenly reduces or stops their intake. Caffeine is a stimulant found in beverages like coffee, tea, and energy drinks. When the body becomes accustomed to caffeine, its absence can lead to various symptoms. Common symptoms of caffeine withdrawal include headaches, fatigue, irritability, and difficulty concentrating. These symptoms typically begin 12 to 24 hours after the last caffeine consumption and can last for several days. The severity and duration of withdrawal can vary depending on the individual's usual caffeine consumption levels.