Why Do Hot Tubs Dehydrate You?

Remaining well-hydrated is absolutely essential for our well-being.  You probably already know that our bodies are made up of around about 60% water. It’s therefore not surprising to learn that if we become dehydrated then our bodies start not functioning at their best. 

It’s very easy to become dehydrated in a hot tub and to start to feel unwell. So, why is it that getting dehydrated in a hot tub is such a common experience and what can you do to prevent it from happening to you?  I decided to do some research into hot tubs and hydration and this is what I found out:

 Why do hot tubs dehydrate you?  The water in a hot tub is commonly 2 or 3 degrees higher than our body temperature.  This means that we sweat in a hot tub to keep our body temperature regulated. As we sweat we lose water and can dehydrate. As we are relaxing in a hot tub rather than exercising it’s easy to forget to keep drinking which is why many people end up becoming dehydrated. 

There are a number of other reasons why people frequently become dehydrated in hot tubs as well and we’ll look at those in a few minutes so that you can be careful to avoid them. First of all, let’s look at what being hydrated means and, more importantly, what happens when you become dehydrated.

How can you tell if you are dehydrated in your hot tub?

The first thing to say is that if you have noticed any symptoms of being dehydrated whilst in your hot tub then, to a certain extent, you have left it a little bit late and you should get out of your hot tub cool down and rehydrate immediately. The key is to be aware that dehydration can occur in your hot tub and to take preventative measures if possible.

Medlineplus.gov describes dehydration as occuring when your body is losing more fluids than it is taking in and therefore can’t work properly. These are the main symptoms of dehydration that you should look out for.

Feeling thirsty and a dry, sticky mouth – This is the most obvious symptom of being dehydrated and one that we will all be fairly familiar with.  If you already feel thirsty then you are probably well on your way to being dehydrated so, as soon as you get the dry or sticky mouth, then you should really be drinking. 

However, not all of us are particularly good at recognizing this feeling of thirst so, if you know that you don’t regularly drink as much as you should do throughout the day, it might be worth carrying a water bottle with you as a visual reminder so that you can sip regularly to stay hydrated.

There seems to be a lot of different ideas as to how much we should be drinking per day.  I read a number of sources that say around about 2 litres of water is the recommended daily intake but the Mayo Clinic does actually recommend up to 3.7 L of fluids per day for men and 2.7 L per day for women.  Apparently about 20% of our water intake is derived from food which is good to know and we also will possibly drink tea coffee and other beverages so it doesn’t need to be 100 % water. 

However, rather interestingly I did read that even a water deficit of as little as 1.36% In women can lead to lack of concentration, fatigue, headaches and feeling unwell.

Feeling tired, confused or irritable – Research has shown that even been mildly dehydrated can cause feelings of tiredness, confusion and irritability. Interestingly, being in a hot tub, to a certain extent, will very naturally counteract these feelings.  You will be in a relaxed state which will most probably put you in a good mood so if you are feeling irritable in your hot tub then it could well be that you are overheating and dehydrated. It can be be easy when you are relaxing in the hot water to confuse the feeling of extreme relaxation with feeling tired as well which can make it difficult to recognise this as a being a symptom of dehydration.

Blurry vision or headache –  Getting a headache or blurry vision for some people is a very common symptom of dehydration.  This can sometimes be accompanied with feelings of nausea and the headache can also develop into a full-blown migraine if the body is not hydrated quickly and remains too hot. 

Muscle cramps – Having muscle cramps or tightness in your muscles particularly after exercise is a sign of severe dehydration. It happens because of a loss or both water and salt in the body and can be obviously prevented by remaining hydrated whilst exercising but also by drinking water that is infused with electrolytes which will replace the salts more effectively than plain water alone.

You aren’t sweating –  If you know that you are hot and you aren’t actually sweating then you are most likely severely dehydrated. The body’s cooling system relies on sweat to cool you down and if you do not have enough fluid in your body to allow for your body to sweat then you are going to overheat and dehydrate very quickly.

Dark – colored urine –  If your urine is a dark brown colour rather than being a light straw yellow then this is also a sign that you are dehydrated.

 

Why do people not notice getting dehydrated in a hot tub?

So I’m sure that having read the above information you’re pretty much familiar with what it feels like to be dehydrated.  Most of us know that when we are thirsty we need to drink more and when we are getting a headache we are probably dehydrated. So why is it that so many people still managed to suffer the effects of dehydration when in a hot tub?

It’s hard to sweat in a hot tub – First of all, bear in mind that it’s actually quite hard work for our bodies to sweat and keep us cool in a hot tub. You will probably be almost completely submerged up to your neck in water that is above your body temperature so the only part of the body that gets chance to really cool down is the head. This is a relatively small area compared with the rest of our body surface area and so we can start to sweat profusely.

You don’t notice sweat in a hot tub – The second problem is that you don’t really notice that you are sweating so profusely in a hot tub because you are already wet! You might not realize how much sweat you are losing because you are wet already and it doesn’t register in your mind that you need to drink until it’s too late and you are well on your way to becoming dehydrated.

Hot tubs are often in very hot positions – This isn’t helped by the fact that hot tubs are often located in sheltered sunny spots. This is great for keeping the hot tub warm and also for when you are getting in and out of the hot tub and lounging around but, if you are submerged in very hot water and the sun is beating down on your head as well, you will have a very hard time not to overheat.

Not exercising / out of mind – We also tend to associate sweating and keeping hydrated with exercising and working hard. Being in a  hot tub is the complete opposite of this and so we are just not in the right frame of mind to drink regularly.

Drinking alcohol – However, when we do drink in a hot tub many of us go for an alcoholic drink. This fits in really nicely with the chilled out and relaxed vibe of the hot tub experience but alcohol is well known for dehydrating you. This puts an even greater strain on the body which is already working hard to keep cool and hydrated. Adding alcohol into the mix makes the risk of dehydration much higher.

Hot tubbing after exercise – Many people also like to jump into the hot tub after a workout or exercise. This is great as it relaxes muscles and is a great way to rejuvenate your body. However, you might already be overheated or dehydrated from exercising even if you are not experiencing any of the symptoms as yet. Getting into the hot tub will fast track the dehydration and cause you to start feeling unwell more quickly.

Forgetting how long you have been soaking– Finally, it can be very hard to keep track of how long you have been in a hot tub. In many ways this is great because you will probably be in a very relaxed state, unplugged from your phone and maybe just chatting to family or friends. However, if you do lose track of the time you won’t be able to stay in your hot tub for the recommended 15 – 30 minutes or so before you will possibly start overheating and dehydrating. Even if you have water and are trying to remember to drink losing track of time or getting absorbed in conversation is an easy way to forget to regularly take sips of water.

Why do I get a headache after being in a hot tub?

The most likely reason for getting a headache in your hot tub is that you are becoming dehydrated. Try to drink sips of water regularly whilst you are soaking and also remember not to stay in any longer than the recommended 15 – 30 minutes at a time.

It is also possible that you are reacting to the chlorine in the hot tub. Some people are very sensitive to breathing chlorine in and it can cause respiratory issues and possibly headaches. Check that your chlorine levels are at a safe level and, if the problem persists consider changing to another sanitizer. 

It’s always a good idea to make sure that there is a good flow of fresh air around your hot tub. If you are indoors then good ventilation will be vital but, even if you are under a gazebo or in a sheltered spot in the garden try to allow space for the breeze to flow round.

This will remove the chemical vapors from the hot tub and also the cooling breeze will help to keep your body temperature regulated meaning that there will be less risk of dehydration and headache.

How much do you sweat in a hot tub?

First of all it’s important to realise that we do actually sweat whilst in the water. The effects of sweating aren’t very effective underwater obviously but we still do it. You will lose anywhere between 200 milligrams and 700 milligrams of sweat in an hour in a hot tub. So, taking an average of 500 milligrams – that’s the equivalent of ½ a litre or just over a pint of sweat.

This does seem to be a huge amount! Probably the most concerning thing is that all of this sweat just gets taken into the water! If there are a number of bathers in the hot tub and the hot tub is in use for a few hours the amount of sweat in there is fairly disgusting.

Thank goodness for modern filtration and sanitization systems!

How to prevent dehydration in your hot tub

So, having learned all of this how do we go about preventing dehydration in a hot tub?

Use a water bottle – The most important thing to do to prevent dehydration is to drink frequently. You could just rely on remembering to have a glass of water every so often but, if you have a set quantity of water in a water bottle you will find it much easier to keep track of your fluid intake.

A water bottle will also act as a visual reminder to drink. If it’s there on the side of your hot tub you are more likely to notice it and to actually use it. One of the most common problems with getting dehydrated is not actually realizing that you are dehydrated until it’s too late. The water bottle method is one way of trying to prevent this from happening.

Stay aware of the time – It’s very easy to lose track of the time in your hot tub and to stay soaking for too long. The recommended maximum time is between 15 and 30 mins as this will prevent your body from overheating too much. Once the time is up it’s important to get out and to cool down before going back into the hot tub again. Obviously, if you do overheat you are going to get dehydrated and start to feel unwell.

Try to either set a timer or have a clock within sight when you are in the hot tub. You can get sand timers which will let you know when time is up or a simple kitchen timer or alarm on your phone will do the job just as well.

Remember, just becuase time is up on your soak it doesn’t mean that the fun is over. Take a little while to rehydrate and cool off away from the hot tub and then you can safely return for another session.

Don’t get in already hot or dehydrated – It’s also important to get into the hot tub well hydrated and with your body at normal temperature. If you have been exercising then you may already be dehydrated or over hot so take some time to relax, cool off and take on some fluids before getting into the hot tub.

If you are already hot and dehydrated when you enter the hot tub the chances are that you will dehydrate further very quickly and start to feel unwell.

Get in the shade – If your hot tub is in full sun have a think about how you could potentially provide some shade so that you have a chance to keep cooler. Sun sails and sun shades work well and you might want to maybe consider a gazebo or shelter if yoou want something more permanenet.

Avoid alcohol – This is the big one! In many ways, there’s nothing like sipping your chilled favorite alcoholic beverage whilst relaxing in the hot tub! However, just be aware that alcohol does lead to dehyration. If you are going to drink alcohol in your hot tub then it’s a good idea to alternate alcoholic drinks with water and to keep your hot tub sessions relatively short to prevent overheating and dehydration.

Related Questions:

Should you drink in a hot tub? It’s a very good idea to drink water and other non-alcoholic fluids whilst in a hot tub as this will help to prevent dehydration. Drinking alcohol is not recommended as it dehydrates the body more quickly.

If you do choose to drink alcohol whilst in a hot tub then try to alternate the alcoholic drink with a non-alcoholic one and stay in the hot tub for shorter periods of time to help prevent overheating and dehydration.

Why is staying in a hot tub too long bad? If you stay in a hot tub for too long there is a risk that your body will overheat and that you will start to suffer from the effects of dehydration.

Can a hot tub make you dizzy? Yes, being in a hot tub can make you feel dizzy. As you sit in the warm water your blood vessels dilate leading to a drop of blood pressure. It’s this lowering of the blood pressure that can lead to dizziness.