How To Know if Your Kid Is Dehydrated — and How To Prevent It

Summer brings seemingly endless opportunities for fun for kids. There are splash-filled pool days, neighborhood kickball games, camping trips and just running around the yard.

But when the temperature rises, so does the risk for dehydration — and it can happen faster than you might think.

Pediatricians Richard So, MD, and Paula Sabella, MD, explain how to recognize symptoms of dehydration in kids, as well as how you can help them stay hydrated so you can have a safe summer.

Signs and symptoms of dehydration

While every child is different, here are some general signs of dehydration to look out for:

Irritability and drowsiness

Dehydration can cause children to feel tired and irritable, so pay attention to how their mood progresses throughout the day. A sudden change may point toward early dehydration.

“You may see them get a little more fatigued on the playground, a little sluggish or even a little cranky,” explains Dr. So.

And if your child is a young athlete, watch how they’re moving at practices or games for possible signs of dehydration. Performance will start to decline as dehydration begins to set in.

Decreased urination

When it comes to dehydration, it’s not just about the input of fluids. It’s also about urine output. With kids of all ages, Dr. Sabella says that urination changes are a major red flag.

Let’s start with color. Your child’s urine should normally be clear or light yellow. “If a child’s urine appears golden, darker in color or seems concentrated, this suggests dehydration and is an indication to give your child more fluids,” she explains.

Additionally, a decrease in urination is a serious sign of dehydration in children. If your child is an infant, call their pediatrician if they’ve had fewer than six wet diapers in a day. For older children, reach out if they’ve had no urine output for eight hours.

Quick breathing and fast heart rate

Especially during an active day, it’s normal for your child to breathe faster than usual. But keep an eye on how fast they’re breathing and their heart rate.

“If you’re dehydrated, it decreases your blood volume and affects your ability to dissipate heat in your body,” explains Dr. So. (The effect on the cardiovascular system leads to an increase in heart rate.)

Fast breathing and a quickening heart rate that doesn’t subside is usually a clear sign of dehydration — especially if your child’s heart rate goes higher than 110 beats per minute.

If their heart rate doesn’t go down after they drink water and rest, reach out to a healthcare provider to have them examined.

Vomiting

In extreme cases of dehydration and heatstroke, your child may exhibit symptoms of nausea and vomiting. This is a clear sign of your body reaching its limit from the heat and lack of hydration.

“The biggest red flag is if a kid is vomiting,” relays Dr. So. “That's a predictor for heatstroke.”

Pale skin and sunken eyes

If you notice your child’s skin getting pale, this can be a sign that they’re experiencing severe dehydration. Along with this, look out for their skin appearing splotchy or their eyes looking sunken in.

Dehydration signs based on age group

There are different signs and symptoms to look out for based on your child’s age, too.

How to tell if a baby or toddler is dehydrated

Identifying dehydration in babies and toddlers requires a little more investigation. While small children can’t express thirst with words, behaviors can reveal how they’re feeling.

Consider these clues of dehydration in infants and young children:

• They’re sleepier and less playful.
• They’re more irritable than usual.
• The soft spot on their head is sunken in.
• There’s a decrease in wet diapers.
• Fewer or no tears when crying.

“With infants, the clues to dehydration may be subtle,” says Dr. Sabella. “However, if you notice any of the signs, contact your child’s healthcare provider right away.”

How to tell if an older child is dehydrated

Older kids tend to show more of the familiar symptoms of dehydration than younger children. They also may be hesitant to sit out a bit at a sports practice or stop activities even if they’re feeling symptoms.

So, it’s important to help your older kids and teens understand the signs of dehydration and when they need a hydration break.

Signs of dehydration in older children include:

• Dry mouth or cracked lips.
• Dark or concentrated urine.
• A decrease in urination.
• Flushed skin or skin that feels dry or warm to the touch.
• Headache.
• Dizziness, weakness, sleepiness or feeling faint.
• Irritability.
• Cramps.
• Confusion.

Again, you should call your child’s provider if they show these symptoms. If your child is an athlete, extra care needs to be put in to make sure they aren’t reaching their limit with sports and activities.

How to prevent dehydration in children

Dr. Sabella says that hydration is important for everyone, especially on hot and muggy days.

“For older children and teenagers, water remains the preferred drink for hydration,” she states. “Teens can drink sports drinks to restore electrolytes they might have lost through excessive sweating and exercise. After a significant amount of vigorous exercise (about an hour or so), it’s OK to drink sports drinks in conjunction with water to recover.”

She adds that breast milk or formula is the main source of hydration for infants. She strongly recommends not giving infants water or diluting formula with it.

Make sure your child takes breaks

It’s hard to pull kids away from the fun, but it’s also necessary on the hottest days.

“During any exercise or activity, it's important to ensure good hydration in children,” emphasizes Dr. Sabella. “When it’s warm outside, hydration is absolutely necessary and kids of all ages should take breaks every 20 minutes.”

These breaks should give children the chance to hydrate, rest and get some shade or be in an air-conditioned or cooler environment.

Plus, make sure you always have a “cool down” zone available. Whether you’re on a beach or a soccer field, ensure your child has easy access to water, ice and a shady spot to chill out if needed.

“Sometimes, the best thing you can do for the little ones is give them a popsicle and a break from playing,” she adds.

Hydrate the night before

During the hot summer months, drinking water during an outdoor activity may not always be enough.

“When we talk about preventing dehydration, whether you’re playing sports or you’re just going to the playground, hydration actually starts the night before,” explains Dr. So.

In fact, he recommends that kids or teens focus on getting enough fluids the day before a big tournament or practice so they start with a “full tank” of hydration in their body. They should also drink plenty of water the morning of the event as well.

“You start with a full tank and there’s going to be fewer mental errors and less of a chance to get dehydrated,” he adds.

Avoid giving your child sugar or caffeine

Two things that aren’t good for dehydration: sugar and caffeine.

If your child is dehydrated, Dr. Sabella says sugary foods and drinks aren’t wholesome options. Stay away from caffeinated energy drinks, as well as caffeine, may act as a diuretic, causing your child to urinate more and speed up the dehydration process.

When is it too hot for kids to play outside?

Another question many parents and caregivers have is when the outdoors should be off-limits due to the heat. Dr. Sabella says it’s best to weigh hot-weather scenarios on a case-by-case basis.

But in general, you may have seen recommendations saying that children shouldn’t play outside when the heat index starts to reach around 90 degrees Fahrenheit (32 degrees Celsius) or higher.

“This is a good recommendation, but it’s good to consider the specific circumstances when determining if it’s safe for your child to go out and play,” she clarifies.

In other words, it depends on your child’s specific situation and preparation.

For example, consider two children on the same soccer team playing a game on a hot day. If one child hydrates the night before plus during and after the game while also taking breaks, they’re in a safer spot than a child who doesn’t hydrate and rest.

The bottom line

Sunny days and warm temperatures can open a world of possibilities for kids. From sports games to long days at the playgrounds, it’s important to know the signs and symptoms of dehydration before you get your summer activities into full swing.

Be sure your kids are hydrating before any big games or play dates and have a cool-down plan if they start to feel irritated or drowsy.

With these tips, you can make sure your kids have a fun (and hydrated) summer.