Signs of overhydration include symptoms such as excessive thirst, frequent urination, and swelling, particularly in the hands, feet, or face. A dangerous condition known as hyponatremia can develop, where low sodium levels lead to nausea, headache, confusion, and in severe cases, seizures and coma. Athletes, especially during prolonged exercise in hot weather, may be at higher risk if they consume large amounts of water without adequate electrolyte balance. Monitoring fluid intake and ensuring proper hydration during activities is crucial to prevent these symptoms.