Dehydration may seem like something that only occurs to marathoners or desert castaways, but in reality, it’s much more widespread—and much more insidious—than you’d believe. It can happen to anyone, from children to adults to the elderly. Think of your body as a finely tuned machine, and water as the fuel that keeps the wheels turning. When you don’t get enough, things can easily become chaotic.
Water is a huge part of what we’re made of, to 78% of our bodies, precisely. Your heart and brain are roughly three-quarters water, your kidneys and muscles almost 80%, and even your bones rely on it. Water helps digest food, sweeps waste out, keeps joints lubricated, makes saliva, controls chemicals, carries oxygen, protects organs, and keeps you warm. When you’re hot or physically active, your body also loses heat by sweating. Sweat is equivalent to water loss, and if you don’t restore it, your body starts to fail.
Dehydration results when you lose more water than you’re taking in. That may be from sweating on a hot day, fever, vomiting, diarrhea, or even not drinking enough water. Certain medications, including diuretics, also hasten the loss of fluids. While thirst is the body’s built-in warning system, not everyone catches it right away. Babies, toddlers, and old people are especially at risk, as they might not be able to express or even notice thirst as strongly.
The symptoms of dehydration are not always noticeable. Adults may have the following symptoms: headaches, exhaustion, dizziness, dry mouth, rapid heart rate, loss of appetite, reddened skin, swollen feet, muscle spasms, difficulty managing heat, constipation, and dark-colored urine. Your urine should be pale, light yellow. If it’s darker, you need more fluids. In children, watch for the following: dryness of the lips and tongue, absence of tears with crying, fewer wet diapers, sunken eyes, dry skin, fast breathing, or cold, blotchy hands and feet.
One of the biggest shocks to learn about dehydration symptoms is a headache. When you’re fluid-deprived, your brain can contract slightly, retracting from the head and exciting pain in the surrounding nerves. It might feel like a pressure headache, a throbbing pain, or something in between—and it might worsen if you move. If your headache clears up after hydrating and resting, dehydration is likely to blame.
But it is not merely a matter of getting a headache or being tired. Severe dehydration can be dangerous. It can cause a disorder in your body’s electrolytes, leading to heat disorders like heatstroke, affecting kidney function, and even result in shock, coma, or death if not treated. In extreme situations, like cholera, where people lose too much fluid from vomiting and diarrhea, dehydration can kill within hours. Dehydration is especially dangerous for kids because it can make people have low blood sugar and can cause kidney issues if it happens quickly.
The good news? Dehydration is almost always preventable. The secret is to drink water all day long, not just when you’re thirsty. Pack a refillable water bottle, opt for water instead of sugary or caffeinated drinks, and try adding lemon or lime if you require a little flavoring. Keep in mind that foods like vegetables, fruits, and soup also count toward your hydration. If you are active or exercising outdoors in the summer heat, it is important to drink more water before, during, and after exercise. While sports drinks can help replenish electrolytes if you’re sweating heavily, water is enough for most daily needs.
Everyone’s water needs are different. Your age, weight, activity level, and the climate you live in are taken into account. The old “eight glasses a day” rule of thumb is a good starting point, but if you have medical conditions like diabetes or heart disease, talk with your healthcare provider to find out what will be best for you.
Staying hydrated isn’t just about quenching your thirst—it’s about helping your body function at its best, keeping your mind sharp, and staying energized. So the next time you’re feeling off, try drinking a glass of water. It might be just what your body needs.