When the weather turns hot, many people wonder, “Should I drink water or a sports drink?” or “Should I be drinking an oral rehydration solution every day?”
In fact, the best drink for staying hydrated depends on the situation.
In this article, we look at the differences between water, sports drinks and oral rehydration solutions, based on research data.
For Everyday Hydration, Water Comes First
For staying hydrated in daily life, water is all you need.
We lose about 2 to 2.5 liters of water a day through breathing, sweat, urine and more. That is why it is important to drink small amounts often, before you start to feel thirsty.
Unless you are sweating heavily, water is enough to replace the fluids your body needs.
Sports Drinks Are Recommended When You Sweat a Lot
When you sweat heavily during exercise, outdoor activities or time under the blazing sun, you lose not only water but also electrolytes such as sodium.
In these situations, drinking large amounts of plain water alone can lower the sodium concentration in your body, making it harder to retain fluids.
A systematic review of 19 studies published in 2024 suggested that, after dehydration from exercise, sports drinks containing carbohydrates and electrolytes may be more helpful for rehydration than water alone.
In other words, when you have sweated a lot, it is important to replenish electrolytes as well as water.
Oral Rehydration Solutions for Heatstroke and Dehydration
If you are dehydrated because of heatstroke, diarrhea or vomiting, an oral rehydration solution is more suitable than a sports drink.
Oral rehydration solutions are designed with a balance of water, sodium and glucose that the body can absorb most easily.
This is because they make use of a mechanism in the small intestine called the “sodium-glucose cotransporter (SGLT1).”
When sodium and glucose are absorbed together, water is also taken into the body efficiently.
For this reason, many studies as well as guidelines in Japan and abroad show that, when you need to rehydrate quickly, such as with heatstroke, oral rehydration solutions can replenish water and electrolytes faster than water or typical sports drinks.
Choose Your Drink to Match the Situation
Here is a simple guide:
• Everyday hydration: water
• After heavy sweating: a sports drink
• With heatstroke or signs of dehydration: an oral rehydration solution
Keep in mind that sports drinks contain a lot of sugar, and oral rehydration solutions have a high sodium concentration, a composition meant for times of dehydration.
For that reason, neither is meant to be your regular, everyday drink for hydration.
Summary
When it comes to hydration, what matters is not only “what you drink” but also “when you drink it.”
Make water your everyday basic, choose a sports drink when you have sweated a lot, and an oral rehydration solution for heatstroke or dehydration. This will help you stay hydrated more effectively.
The hot season is also a time when it is easy to feel unwell.
We hope this helps you remember to drink often, take it easy and look after your health.