EAU CLAIRE, Wisconsin — Dehydration can affect much more than your thirst. It also can place extra stress on your heart and cardiovascular system, explains Brodie Marthaler, M.D., a cardiologist at Mayo Clinic Health System in Eau Claire.
“Think of the heart as a pump. For it to work properly, enough blood needs to return to it with every heartbeat,” Dr. Marthaler says. “When you become dehydrated, the amount of fluid circulating in your bloodstream decreases. That means less blood returns to the heart, so it has to work harder to keep blood moving throughout your body.”
Your body has several built-in ways to respond to dehydration. Blood vessels narrow to help maintain blood pressure, and your heart beats faster to keep blood moving. If dehydration becomes more severe, those usual responses can begin to fail. As a result, organs such as the brain, kidneys, liver and digestive system may not receive enough blood to function properly.
Recognizing dehydration and knowing your risks
As dehydration worsens, symptoms can include:
- Racing heartbeat or palpitations
- Fatigue
- Lightheadedness
- Dizziness
- Vision changes
- Shortness of breath
- Chest discomfort
“If dehydration becomes severe, it can lead to heatstroke or fainting,” Dr. Marthaler says. “These are medical emergencies and should be evaluated by a healthcare professional immediately.”
Anyone can become dehydrated, but some people are at greater risk, including:
- Older adults
- Children
- Athletes
- Outdoor workers
- People with heart disease
- People taking certain medications
“People with heart failure or other forms of heart disease should be especially careful,” Dr. Marthaler adds. “Their hearts may have less reserve to respond to the added stress of dehydration. Many also take medications that remove fluid from the body, lower blood pressure or slow the heart rate, which can limit the body’s usual ability to compensate.”
Staying hydrated and preventing complications
There isn’t a one-size-fits-all recommendation for how much water you need. For most healthy people, thirst is a reliable guide. If you feel thirsty, drink something. If you know you’ll be spending time outdoors in the heat or exercising for an extended period, increase your fluid intake beforehand.
Dehydration isn’t always easy to recognize, so it helps to look for other signs. Dry mouth, dry skin, dark urine, foamy urine or a burning sensation when you urinate may all indicate you need more fluids. One of the simplest ways to monitor your hydration is to pay attention to the color of your urine. Pale or clear urine generally suggests you’re well hydrated, while darker urine may be a sign that you need more fluids.
Water is an excellent first choice for staying hydrated, but if you’re truly dehydrated, water alone may not always be enough. Your blood contains electrolytes such as sodium, potassium and magnesium. Drinking water along with consuming something salty may help replace both fluids and electrolytes. People participating in prolonged exercise or endurance activities also may benefit from electrolyte-containing sports drinks.
Highly caffeinated drinks also can contribute to dehydration. If you’re trying to rehydrate, choose water or electrolyte-containing drinks instead of sugary drinks or soda.
“The best way to prevent dehydration is to stay ahead of it. Make drinking fluids a regular part of your day. Drinking smaller amounts throughout the day is often more effective than consuming a large amount all at once,” Dr. Marthaler says. “If you’ll be gardening, exercising or working outdoors in hot, humid weather, plan ahead, stay aware of how you’re feeling and adjust your activities if needed.”
Most importantly, know your personal risk. If you’re older, have heart disease or take medications that affect your body’s fluid balance, you may need to pay especially close attention to staying hydrated. Planning ahead, listening to your body and recognizing the signs of dehydration can help protect your heart and your overall health.