Dehydration is a condition that has many different signs and symptoms. It’s important to know the warning signs of dehydration so that they can be addressed as early as possible for optimal health. The most common sign of dehydration is dry mouth, which may cause bad breath or sticky saliva. Other indicators are dark yellow urine, excessive thirst, lethargy, light headedness, headache, and dizziness. These often lead to other complications such as fainting spells or seizures because the brain does not have enough water to function properly. You should immediately consult a doctor if you experience any of these symptoms for more than an hour at a time!