How Can I Avoid Heat Exhaustion? with Dr. Rahul Sharma

Faith: Welcome to Health Matters, your weekly dose of health and wellness from New York Presbyterian. I’m Faith Salie.

Between the scorching temperatures and the stifling humidity, it’s important to be cautious in the extreme heat this summer.  Joining me this week is Dr. Rahul Sharma, emergency physician-in-chief at NewYork-Presbyterian/Weill Cornell Medical Center, to explain the signs of heat illness, the importance of staying hydrated — including how much fluid you need in a day—and other ways to protect yourself during a heat wave. 

Dr. Sharma, thank you so much for joining us on Health Matters.

Dr. Sharma: Thank you very much for having me.

Faith: It has felt like an extremely hot summer. We feel the heat, and we know the heat can be very dangerous, but it’s not always easy to tell if we’re experiencing something more serious. So, can you explain to us what is heat illness and what are the signs?

Dr. Sharma: Heat illness should really be looked at as a spectrum, which in its mildest form includes heat cramps, followed by heat exhaustion—which are moderate symptoms—to heat stroke, which is the most severe forms. Now heat cramps are the mildest form consisting of painful muscle cramps or spasms. And this could be spasms in your arms, in your legs, and usually treatment is to get in a cool shaded area, drink fluids, stop the activity. You could stretch or massage the affected area, and usually this self-resolves.

Then you get to moderate symptoms, which fall into heat exhaustion. This is a more severe form than heat cramps, and this is usually the result of loss of salt and water. And these patients have heavy sweating. They’re thirsty. Their skin could be, uh, clammy. They could be nauseous. They could be dizzy, and they could have a headache. And these patients, once again, you want to hydrate them, move them into a cool area. They potentially might need to go to the hospital, but if treated adequately, some of them will get better with some IV fluids and no further work is required, unless they have a chronic medical issue, or they actually did pass out. 

And then you have heat stroke which is the most severe form of heat illness and is actually a medical emergency. These patients need to go to the emergency room and 911 should be called. These patients usually have very high temperatures – greater than 104 – because their body’s ability to sweat and cool is impaired. Their skin is hot and dry versus heat exhaustion when it’s very sweaty. They could be confused. Their mental status could be altered. They could even have loss of consciousness. And you want to move them into a shaded area, put on wet or damp cloths on them or ice packs, and call 911, get them to the hospital.

Faith: Why is it that humidity makes heat feel worse?

Dr. Sharma: So, when the humidity is high, it means that there’s a lot of moisture in the air. Now, this could affect our bodies in several ways leading to a range of symptoms and physiological responses. So, uh, number one, you have reduced sweat evaporation. So our bodies cool down primarily through evaporation of sweat. High humidity will slow down that evaporation process because the air is already saturated with moisture. And this could result in overheating. As the body struggles to dissipate heat more efficiently. You know, you could also have increased heart rate. You could start feeling dizzy These are all the different symptoms when you combine high temperature with high humidity.

Faith: One of the biggest risk factors in the heat is dehydration. So let’s talk a bit about why hydrating is so important, especially in extreme heat.

Dr. Sharma: Dehydration can result from excessive sweating, especially during a heat wave. What dehydration does is it actually decreases the amount of blood flow, potentially, that goes to our organs: your heart, your brain, your kidneys. This is why you end up having darker urine. This is why people might feel dizzy. The heart rate might be elevated because the blood that flows to all these areas is limited when you’re dehydrated.

Think of hydration like fueling up your car. Just like your car needs to run smoothly, your body needs water to function well. Now when you’re properly hydrated, you generally feel good. Your energy levels are stable, your skin looks healthy, you’re not constantly thirsty. 

And also, to have appropriate blood flow to our brain, our kidneys, our heart—all of these are dependent on our hydration status.

Faith: How much fluid should we be drinking in a day to be healthy?

Dr. Sharma: A good rule of thumb is to aim for eight cups of fluid a day—now that’s on a normal day—which is roughly 64 ounces. Now that includes water, but also other hydrating drinks like herbal tea or even fruits and vegetables, and food that might have high water content.

However, everyone is different. And also you have to look at the environment you’re in. So, everyone’s needs can be based on various factors like activity level and climate. So it’s important to listen to your body and drink when you feel thirsty. However, this requirement can be several glasses of water even per hour. For example, two to three glasses of water in extreme heat or when you’re outside.

Faith: I think I’ve heard you can’t count your coffee. I’m sure there are a lot of coffee drinkers hoping that you’re going to say, “yeah, coffee counts.” Is that true?

Dr. Sharma: Well, yes and no. So coffee does have water. But coffee also has a diuretic effect, which means that you could actually be dehydrated by drinking excessive coffee. So while coffee does have water, make sure that you’re supplementing with additional water.

Faith: Should you be drinking even if you’re not thirsty?

Dr. Sharma: Feeling thirsty is the most obvious sign that you might need more water. Now on days that are very hot. I would say it’s important to plan accordingly. You know, you should drink on a consistent basis, not just when you’re thirsty. Like, if it’s gonna be a hot day, it’s gonna be 95 degrees, you should be drinking water regardless of if you’re thirsty. 

Now there’s other signs, like feeling tired and sluggish, having a dry mouth or lips, having darker urine, or even a headache, can sometimes – these could also be signs that you should be drinking more

Faith: I would venture to say that most of us don’t drink as much water as we should, even though we know we’re supposed to. So do you have tips to help us keep ourselves hydrated?

Dr. Sharma: Yes. So, It’s good to have a reminder on your phone to say, all right, drink water. Always keep a bottle of water if you’re especially indoors, keep a large bottle of water and have it regularly filled. Whatever works for you, uh, try it. Just like you use reminders to do other things in life, you should use the same types of reminders for water.

Faith: Are there fluids we should avoid?

Dr. Sharma: In general, you want to limit your alcohol intake. Now, if you choose to drink alcohol, make sure you’re also supplementing with enough water, uh, because alcohol could also be a diuretic, it can make you lose water. You should also avoid sugary drinks, especially during a heat wave, as they could also result in you feeling more dehydrated. Um, salty drinks as well, and also caffeinated drinks. Those are in general the types of fluids to avoid, especially during a heat wave. 

Faith: Could you be drinking all the water you should and – and yet still be at risk for heat illness?

Dr. Sharma: Hydration is not the only thing that we need to do, uh, to prevent us from being impacted by heat illness. First of all, you gotta stay informed. Keep an eye on the weather forecasts and heat advisories. Now the CDC actually now offers this heat risk map, which anyone could use. You basically go to their website, put in your zip code, and it will tell you your risk of heat illnesses in your particular area, from either no risk to extreme risk. Prevention is key.

You want to stay inside. You want to stay in a cool, air conditioned area. But, if you must venture to the outdoors, try to avoid the peak heat hours. Don’t go out between 10am and 4pm when it’s extremely hot. 

Drink plenty of fluids, but not only when you’re thirsty. You need to do this throughout the day. Make sure you have adequate amounts of fluid. Every hour, especially if you’re in a hot environment. And as I said earlier, avoid alcohol as it can make you more dehydrated.

Dress appropriately. Lightweight, light colored, breathable clothing is the way to go. Sunglasses, sunscreen, hats, all great ideas. But the most important thing is to monitor yourself. Pace yourself, especially if you’re not used to working or exercising in a hot environment. Don’t ignore the symptoms. If you start feeling dizzy, nauseous, or have a headache, these might be signs that you need to take a break, drink fluids, and slow down.

Your body’s trying to tell you something and it’s important to listen. So, hydration is just one component at preventing heat illness.

Faith: Some people really lean towards electrolyte drinks because they’re very tasty and they have this promise to optimize hydration. How much truth is in that? Who needs to be drinking, you know, sports drinks or electrolyte drinks?

Dr. Sharma: Well, my general recommendation is that if you are eating enough food and you’re not in strenuous exercise for more than an hour, water is just fine, adequate water. Uh, electrolyte drinks certainly could help, but you have to be a little cautious. A lot of these drinks might have added sugar, which actually might not be that beneficial to your overall health. Um. 

If you are drinking water and you’re eating properly, you’re going to get your electrolytes from food. So you don’t necessarily need a supplement of additional electrolytes.

Faith: Dr. Sharma, thank you so much for explaining all this to us.

Dr. Sharma: It was my pleasure to be here and thank you for having me.

Faith: Stay cool, okay?

Dr. Sharma: Yes. [laughs]

Faith: Our many thanks to Dr. Rahul Sharma. I’m Faith Salie.

Health Matters is a production of New York Presbyterian. The views shared on this podcast solely reflect the expertise and experience of our guests. New York Presbyterian is here to help you stay amazing at every stage of your life.

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