Not Drinking Enough Water

It’s when you lose more water than you take in. That makes it harder for your body to do some basic jobs, like keep your temperature steady and clear out waste. You lose water in your sweat, tears, and every time you go to the bathroom. Even breathing takes a little out of you. Usually, you make it up with what you drink and eat. But hot weather, exercise, and sickness can knock you off balance.

Whatever you do, make sure you get in those six to eight glasses, otherwise dehydration could cause a whole host of problems. Here are a few side effects:

1. Persistent headaches. One of the first things you might notice when you’re dehydrated is a throbbing headache. The good news? If dehydration is the cause, it should go away shortly after you drink a large glass of water.
2. Sluggish bowel function. “There are water receptors in the colon, and they pull water from the body to make the stools softer,” says Dr. Moghaddam. “If you don’t get enough water, hard stools and constipation could be common side effects, along with abdominal pain and cramps.”
3. Dull skin. Dehydration shows up on your face in the form of dry, ashy skin that seems less radiant, plump and elastic.
4. Fatigue. If you’re not replenishing your fluid intake, your energy levels could plummet and you could experience fatigue and brain fog. So the next time you reach for another cup of coffee, see if it’s water that you need instead.
5. Weight gain. “Sometimes people mistake thirst for hunger and they eat more, but really they just need to drink more,” says Dr. Moghaddam. “Sometimes if you have a glass of water, the hunger cues will go away.”
6. Dry mouth. If you’re not getting enough water, you can have dry mucous membranes—i.e., a lack of saliva. This can make it difficult to talk, swallow, and even breathe. Luckily, this can easily be solved by drinking water.

More than half your body weight comes from water. So if your levels are off, it can show up in a surprising number of ways. Mild dehydration can make you feel tired and give you a headache. Even your mental focus, mood, and memory can take a small hit. And when you push yourself hard at the gym, all that sweating actually lowers how much blood you have for a bit.

Almost never. These blends of water, salts, and sugars are made for high-level athletes, like marathon runners. Most of us don’t need anything more than water during exercise. You’ll only have to work harder to burn off the extra calories from sport drinks. If you do intense training for more than an hour, then they can make sense. Even then, you won’t need to start drinking one until the second hour.

When dehydration is mild or even moderate, you can often kick it with plenty of water. But if you have severe diarrhea or are throwing up, an oral rehydration solution might help. It’s more often kids who need one, but adults can use it, too. The special mix of salts and sugars is a closer match to what the body needs. You can buy it over the counter at a drugstore.

Yes, but no need to panic. That’s just how the body works. By the time you get the urge to quench your thirst, you’re already a little dehydrated. As long as you pay attention and snag a drink when your body tells you to, it’s not a problem. For older adults, the lag might be a little longer. So it can help to make a habit of drinking water, especially when it’s hot out or you’re feeling sick.

This old rule has zero science behind it. But it’s fine as a rough guide. The amount you need to drink depends on how active you are, where you live, and your overall health. So listen to your thirst. If you’re not sure you’re drinking enough, check the color of your pee. Clear or pale yellow means you’re all set. Darker means you need to drink up. 

You can lose over a gallon of water a day if you have diarrhea and throw up. Babies and kids are more likely than adults to get dehydrated because their bodies are smaller. Older adults need to be on the lookout because your sense of thirst gets duller with age. Kidney disease and some health conditions can make your body get parched. Pregnant or breastfeeding women need to drink more than usual.

Babies and little kids can’t always tell you what’s going on with their bodies. Look for a dry tongue, no tears when crying, no wet diapers for 3 hours, and more fussiness than normal. When it’s more severe, their mouths will be dry and sticky, and their eyes and cheeks may look sunken. They also may breathe fast and have a fast or weak pulse. And the soft spot on top of your baby’s head may be sunken.

You might be thirsty, and your mouth might feel dry or sticky. You won’t pee very often — under 4 times a day. When you do go, there may not be much pee, and it’ll be dark or have a strong smell. You may feel dizzy or lightheaded, especially when you stand up, and you may pass out. As it gets worse, your thirst cranks up. Your breathing and heart rate may be faster than normal. You can overheat, and you might feel confused or cranky.