Coffee can act as a diuretic, which means it can increase urination and potentially lead to dehydration if not consumed in moderation. When you drink coffee, the caffeine in the beverage stimulates the kidneys to produce more urine, which can result in a loss of fluids and electrolytes from the body. This loss of fluids can lead to dehydration, especially if you don't consume enough water or other hydrating fluids throughout the day. However, it's important to note that the diuretic effects of coffee may not be significant enough to cause dehydration in moderate coffee drinkers who also consume enough fluids to stay hydrated. To avoid dehydration, it's recommended to drink plenty of water and other hydrating fluids throughout the day, and to consume coffee in moderation.