Why Hot Tubs Can Lead to Dehydration and How to Stay Hydrated

Soaking in a Hot Tub feels like bliss—until you step out dizzy and parched! The short answer? Heat makes you sweat (even underwater), leading to sneaky dehydration. Want to avoid the hot tub hangover? Stick around for simple tips to stay hydrated while you soak!

The Science Behind Hot Tub Dehydration

Heat-Induced Sweating: Your Body’s Cooling Mechanism

Ever noticed how you start sweating when it’s hot outside? That’s your body’s natural way of cooling down. The same thing happens in a hot tub—except you don’t realise it because you’re already wet!

Warm water raises your body temperature, triggering your sweat glands into action. But instead of evaporating like it would in the open air, that sweat just mixes into the water, making it easy to miss how much fluid you’re actually losing.

How Sweating Leads to Fluid Loss

Sweating isn’t just about losing water—it also drains your body of electrolytes like sodium and potassium. These little guys keep your muscles working and your energy levels stable.

Lose too many fluids without topping them up, and you could end up feeling sluggish, dizzy, or worse.

Vasodilation: Blood Vessel Expansion and Fluid Shifts

Ever felt a little lightheaded after a long soak? That’s vasodilation at work. When you’re in a hot tub, your blood vessels widen to help release excess heat.

While this helps your body cool down, it also causes fluids to move away from your organs and muscles. That’s why you might feel a little wobbly when you stand up too quickly after a soak.

The Impact of Vasodilation on Blood Volume

With fluid shifting around, your overall blood volume drops. Less blood circulating means your heart has to work harder, which can lead to dizziness, fatigue, or even fainting.

Combine that with fluid loss from sweating, and you’ve got a recipe for dehydration.

Duration and Temperature: The Key Factors

The hotter the water and the longer you soak, the greater your risk of dehydration.

How Longer Soaks Increase Dehydration Risk

A 10-minute dip? No problem. A 45-minute soak? Your body might start waving a white flag.

Spending too long in a hot tub forces your body to work overtime to regulate temperature, increasing sweat production and fluid loss.

The Effect of Hot Tub Temperature on Fluid Loss

Cranking up the heat might feel amazing, but temperatures above 40°C (104°F) speed up dehydration. Your body struggles to cool itself down, leading to even more sweating and fluid depletion.

Exacerbating Factors: Alcohol, Caffeine, and More

Alcohol’s Diuretic Effect: A Double Whammy

Few things feel fancier than sipping wine in a hot tub. Unfortunately, it’s one of the worst things you can do for hydration.

How Alcohol Increases Urination and Dehydration

Alcohol is a diuretic, meaning it makes your body get rid of more fluid—mostly through extra bathroom trips. Mix that with the sweating from the hot tub, and you’re losing double the fluids in half the time.

Caffeine’s Role: Another Diuretic to Consider

Morning coffee in the hot tub? Sounds relaxing, but caffeine can also make dehydration worse.

The Impact of Caffeine on Hydration Levels in a Hot Tub Setting

Like alcohol, caffeine tells your kidneys to flush out more water. So while you’re enjoying your soak, your body is busy losing fluids faster than you can say “tea time.”

Other Contributing Factors

Some people are more prone to dehydration than others.

Pre-existing Medical Conditions

If you have heart problems, kidney disease, or diabetes, your body may already struggle with fluid balance. Adding a hot tub into the mix could make things worse.

Certain Medications

Diuretics, blood pressure meds, and some antidepressants can increase fluid loss. Always check with your doctor if you’re unsure about soaking safely.

Recognising the Signs: Hot Tub Dehydration Symptoms

Common Dehydration Symptoms

Headache and Dizziness

A pounding headache or sudden dizziness? Your body is likely crying out for water.

Muscle Cramps and Fatigue

When electrolytes drop too low, your muscles start rebelling. Cramps and weakness are common signs you need to rehydrate.

Dry Mouth and Skin

Hot tubs may be filled with water, but that doesn’t mean your skin stays hydrated. If you feel like you’ve been licking sandpaper, it’s time for a drink.

Increased Heart Rate

Dehydration forces your heart to pump harder to compensate for lower blood volume. If your pulse feels unusually fast, step out and rehydrate.

Dark Urine

Your pee should be light yellow. If it’s dark, you’re dehydrated—simple as that.

Recognising Severe Dehydration

Extreme dizziness, confusion, or feeling faint? That’s a red flag. Get out, cool down, and drink fluids immediately.

Staying Hydrated: Prevention and Mitigation Strategies

Pre-Soak Hydration: Setting Yourself Up for Success

Drinking Water Before Entering the Hot Tub

Start hydrated, stay hydrated. Sip some water before getting in to give your body a head start.

During Your Soak: Maintaining Fluid Levels

Keeping Water Readily Available

Keep a water bottle within reach. Make drinking water as easy as relaxing in the tub.

Sip Regularly, Even If You Don’t Feel Thirsty

Thirst is a late warning sign. Get ahead of it by drinking small sips throughout your soak.

Post-Soak Recovery: Replenishing Lost Fluids and Electrolytes

Importance of Electrolyte Drinks

Water is great, but sometimes you need a boost. Sports drinks or electrolyte tablets help replenish lost minerals.

Rehydrating with Water and Fruit

Foods like watermelon and oranges pack a hydrating punch, giving you fluids and nutrients in one go.

Hot Tub Best Practices

Limiting Soak Time

Stick to 15–20 minutes per session to prevent excessive fluid loss.

Controlling Water Temperature

Keep the temperature under 40°C (104°F) to reduce dehydration risk.

The Role of Electrolytes in Hot Tub Hydration

Understanding Electrolyte Loss

Key Electrolytes Lost Through Sweat

Sodium, potassium, and magnesium are essential for hydration and muscle function.

Replenishing Electrolytes: Drinks and Foods

Sports Drinks and Electrolyte Supplements

Choose low-sugar options for better hydration without the sugar crash.

Natural Electrolyte Sources in Food

Bananas, leafy greens, and coconut water are fantastic natural electrolyte sources.

Hot Tubs and Specific Populations: Increased Risk Factors

Elderly Individuals and Dehydration

Older adults don’t regulate temperature as efficiently, making dehydration a bigger risk.

Children and Hot Tub Safety

Kids lose fluids faster than adults, so shorter soak times and extra hydration are key.

People with Existing Health Conditions

Anyone with heart or kidney issues should take extra precautions before using a hot tub.

Final Thoughts

A hot tub should leave you feeling relaxed, not wrung out like an old sponge. Keep an eye on your hydration, limit your soak time, and skip the booze while you bathe. With a little care, you can enjoy the heat without the dehydration headaches. Now, where’s that water bottle?