Skip to main content


There has been an error in displaying this message. Please contact the site administrator.

What’s the difference between thirst and dehydration?

Written By: Simone Sonnier, UT Physicians | Updated: August 2, 2021
Woman drinking water

Warning signs of dehydration can range from fatigue to irritability.

We have all heard the saying, “If you’re thirsty, you’re already dehydrated,” but is there a difference between the two? Deepa Iyengar, MD, family medicine expert with UT Physicians, breaks down thirst versus dehydration and how to stay hydrated during the Texas summer heat.

Thirst or dehydration

Experiencing feelings of thirst is completely normal and should be addressed; however, it is not necessarily a good indicator of dehydration. Other common warning signs your body uses to alert you to drink more water are dry mouth, feeling weak, fatigue, irritability, and headaches.

What it takes to keep one person hydrated may not be enough for another. Iyengar says a person’s weight can sometimes determine the amount of water they need per day.

Deepa A. Iyengar, MD
Deepa A. Iyengar, MD

“Water content is a percent of your total body weight, so the higher the weight of a person, there is an increase in water needs in most cases,” she said.

How to hydrate properly

Iyengar recommends water above all else if you are feeling the effects of dehydration. However, certain sports drinks can be helpful if electrolytes need to be replenished due to excessive sweating, vomiting, or diarrhea.

“Sports drinks can definitely be beneficial in certain situations; however, individuals should be aware of the high sugar content in some of them,” said Iyengar, professor in the Department of Family Medicine at McGovern Medical School at UTHealth.

While trying to replenish your body, it is best to avoid certain foods and drinks. Your favorite cup of afternoon coffee is actually a mild diuretic and can worsen your state of dehydration. Salty snacks and alcohol should also be off-limits until you are feeling more quenched.

“Staying hydrated, especially during the summer months, is key to good health,” said Iyengar. “If you feel like you’re constantly thirsty or are experiencing dehydration symptoms frequently, no matter how much water you drink, it’s important to seek out the care of your primary doctor.”

As the clinical practice of McGovern Medical School at UTHealth Houston, UT Physicians has locations across the Greater Houston area to serve the community. To schedule an appointment, call 888-4UT-DOCS.