Signs of overhydration include symptoms such as nausea, headache, confusion, and swelling, particularly in the limbs. It occurs when excessive fluid intake disrupts the balance of electrolytes, specifically sodium. To prevent overhydration, individuals should monitor their fluid intake, particularly when engaging in activities like endurance sports. It's essential to drink according to thirst and be aware of the body's signals. Consulting with a healthcare provider for personalized hydration strategies can further aid in preventing overhydration.