How Do You Know If You Need to Go to the ER for Dehydration?

It’s normal to get dehydrated every now and then. You might find yourself feeling dizzy while recovering from a stomach bug. Or you may feel lightheaded after exercising on a hot day. But it can be hard to tell how serious your dehydration is when you’re the one experiencing it. 

When dehydration becomes severe, it can cause serious health problems. It can even lead to shock and organ failure. So how can you tell when dehydration is severe? And when should you go to the ER for dehydration? We’ll break it down here. 

What causes severe dehydration?

Dehydration happens when you lose more fluids than you take in. Severe dehydration means that your body doesn’t have enough water to function properly. And this puts your organs at risk for becoming damaged. This is even more concerning if you have a condition that makes it hard to drink fluids to recover. 

Severe dehydration can be caused by:

• Vomiting or diarrhea: Either of these can cause you to lose a lot of fluid, in a short amount of time. And if vomiting or diarrhea persist, it can be hard to drink enough fluid to make up for what your body is losing. 

• Heat: You lose more fluids through your sweat, when it’s hot out. This makes you more prone to dehydration. And depending on the circumstances, severe dehydration can happen without obvious sweating. 

• Vigorous exercise: The more intense your exercise is, the more fluids you lose. Fluid loss is even more of a concern if you exercise vigorously on a hot day. This leaves you at an even higher risk for severe dehydration. 

• Not drinking enough: For most people, your natural drive for thirst will warn you before you get severely dehydrated. But some people — like babies and people older than 65 — have a weaker thirst instinct. So, they’re more at-risk for severe dehydration. 

• Medications: Certain medications can lead to dehydration. For example, diuretics make you pee more. And laxatives can make you lose more fluids from your intestines. 

• Certain medical conditions: Some health conditions — like kidney disease and diabetes — can sometimes make you urinate more often. 

What are the symptoms of severe dehydration?

Symptoms of severe dehydration can be different depending on your age and general health. But in general, someone might experience: 

• Dizziness

• Confusion or grogginess

• Exhaustion

• Sunken eyes 

• Dry, cracked skin

• Extreme thirst

• Dark urine, or low amount of urine

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You can’t always tell exactly how dehydrated someone is from their symptoms alone. For example, a young and healthy person with food poisoning might feel dizzy, but only be mildly dehydrated. On the other hand, an older adult in a hot climate might have few symptoms and be at risk for kidney damage if they are not drinking enough.

Quiz: Should I go to urgent care or the ER?

When should you go to the ER for dehydration?

You should go to the ER if you think you or someone you care about is showing signs of severe dehydration. The symptoms of severe dehydration can be different depending on your age. 

Adults

Young, healthy adults are likely to experience different symptoms with severe dehydration than older adults. 

Symptoms of severe dehydration in adults include: 

• Extreme lightheadedness

• Fainting, especially when going from sitting to standing

• Dark urine

• Muscle cramps

• Headache 

• Nausea that won’t go away

• Increased heart rate (over 100 beats per minute)

Older adults

The signs of dehydration in older adults (over 65 years old) may be more subtle. As people age, their thirst mechanism tends to be weaker. So, they’re more likely to get dehydrated from lack of drinking. And older adults are more likely to have chronic medical conditions. This makes them more vulnerable to the effects of dehydration. 

Older adults can experience all the same symptoms as young adults. But they may also experience milder symptoms, even when dehydration is severe. Older adults might also notice:

• Confusion 

• Sunken eyes 

• Increased lethargy

• General weakness

• Extremely dry skin or cracked lips

• A lower blood pressure than their baseline

Children

The most common cause of severe dehydration in children is vomiting and diarrhea. So, it is especially important to watch for any symptoms of dehydration if your child has a stomach bug. Signs of severe dehydration in children can include: 

• Confusion or changes in mental status

• Exhaustion

• Cold, clammy hands and feet

• Fast heart rate

• Inability to drink fluids by mouth (because of persistent vomiting)

• Very dark pee or not peeing

Babies

Babies won’t be able to tell you they’re thirsty or complain if they have a headache. So, it’s even more important to know what to watch for with your baby. You should go to the ER if your baby is experiencing symptoms like:

• Fewer wet diapers (less than 3 diapers in 24 hours)

• Constant crying

• Appearing more sleepy than usual

• Fast breathing

• Crying with no tears

• Dry cracked lips

• A sunken soft spot on the top of their head

It’s important to remember that wet diapers are a very good indicator of hydration. If your baby still has regular wet diapers every few hours, they are unlikely to be severely dehydrated. If you are unsure what to do, don’t hesitate to reach out to your child’s pediatrician for guidance about your next best steps. 

Can you rehydrate without an IV?

People often assume that if they go to the ER for dehydration, they will need to receive IV fluids. This is when fluids are given through a needle placed in the vein. But not everyone who goes to the ER for dehydration will need IV fluids. 

Healthcare professionals in the ER can determine if you need IV fluids by:

• Assessing your vital signs: Dehydration can affect your vital signs. People who are severely dehydrated may have a higher heart rate and lower blood pressure. 

• Completing a physical exam: They will look for things like dry or elastic skin, poor circulation in your hands and feet, and general mental status.

• Performing blood tests: An electrolyte panel is the best way to assess your overall hydration. 

• Monitoring ongoing symptoms: Someone who is actively vomiting will be more likely to need IV fluids, since drinking fluids is not a good option.

But if your dehydration seems mild or moderate, the ER physician may start by offering you an oral rehydration solution. This involves drinking a liquid that has a good balance of sugar and electrolytes — it is not purely water. Oral rehydration treatments are especially helpful for children. And it spares them needing an IV placement.

How can you rehydrate at home? 

If you think you might be dehydrated, but aren’t yet showing signs of severe dehydration, you can try to hydrate at home. There are several ways to do this: 

• Make your own oral rehydration solution. Making a homemade rehydration solution is especially helpful if you are dehydrated from vomiting or diarrhea.

• Drink frequent, small sips of fluid. If you have been vomiting, your stomach might not tolerate large amounts of fluid, all at once. Instead, start small and drink frequently.

• Drink all kinds of fluids. Remember that you’re not limited to water. You can rehydrate with fluids like soup broth, juice, coconut water, tea, or milk. In fact, these types of fluids are often more helpful in replenishing your electrolytes.

• Eat hydrating foods. Eating water-rich foods like watermelon or grapes can help you rehydrate faster. Popsicles are a great option, especially for kids. Soup is another great way to hydrate from food. 

How can you prevent dehydration?

You can prevent dehydration by making sure that you drink enough fluids for your body. While that might sound easy, you might not notice subtle signs your body needs more fluids. To prevent dehydration, you should: 

• Drink regularly rather than waiting until you are really thirsty

• Drink more than usual when you’re exercising, feeling sick, or in hot weather

• Eat hydrating foods

• Notice if your urine is darker than usual, and start drinking more

Why trust our experts?

Written by:

Karen Hovav, MD, FAAP

Karen Hovav, MD, FAAP, has more than 15 years of experience as an attending pediatrician in a variety of clinical settings. She has worked in a large academic center in an urban city, a small community hospital, a private practice, and an urgent care clinic.

Edited by:

Katie E. Golden, MD

Katie E. Golden, MD, is a board-certified emergency medicine physician and a medical editor at GoodRx.

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