How Hydration Plays a Role in Getting Over Sickness

03.18.2025 | 3 min read

Medically reviewed by Gretchen Goltz, D.O.

Growing up you probably heard the same advice over and over when you were sick: drink plenty of fluids.

Have you wondered why this is such common advice and why hydration plays such a huge role in battling a cold or the flu? Here is the science behind it.

How does hydration help with being sick?

We constantly need to replenish things we lose, and water consumption is no different. When you eat all your food, you have to get more groceries. When your car runs low on gas, you have to fill it back up. We get dehydrated when our body loses more fluid than it absorbs, so when your body loses water – which it does when you sweat, urinate and even exhale – you need to replace what you lose because your body relies on water to function properly.

When we’re sick, we lose more fluid than you might think. Fever-induced sweating, sweating while trying to sleep, coughing, vomiting and diarrhea all expel water from your body. And even small fluid imbalances can cause you to feel dehydrated, which can increase body temperature and make you feel hot. Proper water intake regulates your internal body temperature.

Research shows proper hydration, through water and electrolyte replenishment, helps keep mucus thin and clear, allowing it to better protect you from germs, according to the Cleveland Clinic.

According to the Mayo Clinic, water also helps you get and stay healthy by:

Carrying nutrients and oxygen to cells.
Dissolving nutrients in the bloodstream to make them accessible to the body.
Lessening the burden on the kidneys and liver by flushing out waste products.
Lubricating joints.
Moistening tissues in the eyes, nose and mouth to loosen up stuffiness and congestion.
Protecting organs and tissues.

Drinks to consider and drinks to avoid while sick

Water is the most effective hydration option. If you want to liven up your h2O, add some lemon for a vitamin C boost.

Beyond that, electrolyte solutions like Pedialyte® can replenish your body with the water and electrolytes it loses when you vomit or have diarrhea. But these drinks should be consumed in small amounts as overdoing them could lead to an electrolyte imbalance, which could worsen your symptoms.

Electrolyte-heavy beverages aren’t meant to be all-day drinks. It’s best to drink mostly water as you recover from an illness and focus on replenishing electrolytes through diet. Fruits, vegetables, dairy products like milk and yogurt, beans, nuts, seeds and other whole foods are all rich in electrolytes.

Additionally, juices and sports drinks might seem like solid choices to replenish electrolytes, but their high sugar content can exacerbate stomach problems like nausea and diarrhea.

You should also steer clear of alcohol, which in addition to dehydrating you, can make cold and flu symptoms worse; when alcohol interacts with your immune system it diminishes its ability to fight infections.

How do I know if I’m drinking enough water?

Daily water intake recommendations vary by age, sex and activity level. According to the U.S. National Academies of Sciences, Engineering, and Medicine, the adequate daily water intake is:

About 15.5 cups (3.7 liters) of fluids a day for men
About 11.5 cups (2.7 liters) of fluids a day for women

Call your primary care provider or a medical professional immediately if you believe you are suffering from extreme dehydration, which can cause these serious symptoms:

Irritability or disorientation
Extreme lack of sleep
A consistent inability to keep fluids down
Diarrhea that lasts 24 hours or more
Bloody or black stool

More from MI Blue Daily:

Photo credit: Getty Images