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Why Chlorinated Water Is Your Enemy

By Megan Griffith

Reviewed for medical accuracy by Dr. Jaggi Rao,
MD, FRCPC Double board-certified dermatologist

Not much feels as refreshing as coming home after a relaxing day by the pool. Both your mind and your body feel refreshed; your skin feels loved by the sun, as well as by the chlorinated water. What could go wrong?

Chlorinated water may kill bad bacteria but it can also kill the good bacteria which our skin needs.

Indeed, your day by the poolside has probably brought innumerable benefits for your body. You completed your daily dose of muscle exercising, you soaked up the sun’s rays and their irreplaceable vitamin D content, you boosted your mood by being active yet well-rested. However, your fun outing has likely also had a detrimental effect on another key part of you – your skin. Indeed, while the rest of you was having fun, your hair and skin may have been suffering.

The biggest effect that chlorine has on your skin is that it can severely dry it up1. At the same time, many acne sufferers claim that chlorine benefits their skin. As it usually happens with beauty tricks, especially when it comes to skin problems, people are divided on the issue. The time has come to delve into chlorine’s properties and to evaluate its pros and cons for fighting acne.

What Is Chlorine And How Is It Used?

You probably already know this but let’s go over it, anyway. Chlorine is a substance popularly used in swimming pools and aqua parks with the goal of ridding them of germs and organic matter2. Essentially, we use chlorine to disinfect artificial bodies of water, so that we can soak in them for as long as possible without worrying about our health. If chlorine is not mixed into a pool, the water can become an excellent breeding ground for all sorts of pathogens such as e.coli, Shigella, giardia, etc. This would also allow for algae to form in artificial pools. All of this could lead to Recreational Waterborne Diseases to start emerging from our pools and Jacuzzis. If this sounds like something that came straight out of a horror movie scenario, then you now understand why people pour copious amounts of chlorine into man-made waterbeds.

If you are now beginning to wonder why we bathe in something that kills other organic matter, then you are on the right track. Chlorine is even a key ingredient in the water flowing from American faucets. Luckily, we have had the good sense to start diluting chlorine before dropping it into our water. Otherwise, we would have quickly become victims of the otherwise toxic chemical.

Could Chlorine Worsen Your Acne?

Many swear by the cleansing and relieving properties that the chemical has on their acne. Granted, its germ-killing abilities make it sound like the perfect solution to cleanse your face from the dirt that causes you an endless stream of zits. Particularly, people hope that chlorine would help annihilate the Propionibacterium acnes which fuels breakouts. After all, it does the same with all the other bacteria floating around the neighborhood pool. It is thus true that chlorinated water can reduce a breakout or diminish your zits. It can also dry out particularly stubborn pimples, leaving you with a fresh look for that upcoming summer party.  Just do not spend too much time in the water. Balance is your best friend – you can indulge in swimming around for a bit, but don’t forget to soak up some sun, as well, and let it revive your dried up skin. Also, make sure to regularly moisturize! It does not hurt to also add some protective product to your hair, as chlorine not only affects your complexion, but also your hair; just use a hydrating conditioner and you should be good to go.

However, science suggests that the believers in the beneficial effects of chlorine on skin may also be somewhat misguided. First and foremost, chlorine dries up skin like no other3. Your complexion may be glowing right after being in the pool, but soon after you may already be experiencing the bothersome flaky scaliness on your face and body. If you are lucky, this may be the end of the effect that chlorine has on your skin tone. However, if you are one of those less fortunate pool-goers, you may soon begin to develop zits as a result of your chlorine-filled day of fun.

So, why does the chemical dry up your skin so severely? The explanation is simple. Chlorine attacks the proteins that feed your skin. This leaves the cells on the outer layers of your skin without necessary nutrition and eventually kills them. Of course, the more chlorine there is in a pool, the more extreme this effect will be. This is why you may be sensing the first signs of dehydrated, rough skin as soon as you get home.

Likewise, your skin serves to regulate the hydration of your body according to the environmental factors around it. For instance, your skin’s moisture level can fluctuate depending on how hot or how humid it is around you. Therefore, when the outer layer of your skin becomes damaged, the levels of hydration will no longer be regulated in the same way.

Chlorine And Sensitive Skin

Various research has been conducted in an effort to demonstrate the drying effect of chlorine. Specifically, an experiment from 15 years ago proved that people with severe skin conditions are particularly negatively affected by chlorine. People with atopic dermatitis were placed in contact with increasingly chlorinated water, which immediately considerably dehydrated their skin4 – with its moisture decreasing as the chlorine increased. The chlorine percentage of the tested water never became much higher than that of most pools. It is important to note that this experiment was performed on a small scale – the patients were exposed to chlorine for less than a quarter of an hour. Imagine what a full day by the pool could be doing to your skin – especially if you suffer from frequent breakouts.

You may now be wondering why dry skin would lead to more acne. After all, isn’t excessive oiliness the main cause of pimples? Actually, the effect is often reversed. When your skin is dehydrated, your sebaceous glands work extra hard to develop the necessary natural oils for protecting your complexion. This only leads to a bunch of oil clogging your pores, which – you guessed it – directly leads to acne.

More than that, chlorine is harmful for the buffer that your skin represents between your insides and the various kinds of bacteria that are looking for ways to enter them – especially if your skin happens to be thin and sensitive. To be sure, the acidity of your skin normally relentlessly protects you against germs. However, when its balance is disturbed, as it happens when it is exposed to chlorine, it becomes harder and harder for your outside layers to guard your inner self from trouble.

Generally, it is a good idea to stay away from too much chlorine, whether or not you have acne. From changing your hair color via the proteins by your follicles, to making your skin burn from exposure, this chemical is definitely something from which you want to be protected.

Possible Alternative Explanations For Improved Skin After Chlorine Exposure

While pool bathers certainly may have experienced acne relief after going swimming, this is most probably due to any of the other factors that accompany pool visits. For instance, one of the most logical explanations for the improvement of their skin could be the sunshine they exposed themselves to for hours on end when lounging by the poolside. The amounts of vitamin D that you are able to gain from a summer day in the outdoors can easily account for an improvement in your skin condition. Additionally, the sun also provides hearty amounts of nitric oxide which fights inflammation.

Moreover, the acne relief that chlorine proponents experience after a pool visit could simply be due to the decreased tension in their body after a relaxing summer day. Stress is a key cause of breakouts and the lack of it logically leads to lessened symptoms. A related reason for the alleviation of acne could be the physical exercise that pool-goers get from swimming lap after lap. Last but not least, it is possible that a change in your general environment helped clear your acne. As recurring pimples may be caused by your usual diet or by your city’s dirty air, spending a day in a different place, with clean air and a cleansed water source, could be the reason why your skin improved.

How Much Chlorine Do We Really Absorb?

The truth of the matter is that your body takes in a lot more chlorine than you think. In fact, we not only swim in chlorine, but we may also be washing our bodies and clothes in it. Regardless of the way in which it enters you, your body takes in more than 60% of its chlorine through bodily contact, rather than through ingestion5 through the mouth (via tap water, pool water, etc.). Put simply, this means that while you swim around the pool during your next vacation, you should keep in mind that the chemicals in the water are freely entering your body – even if you are keeping your mouth tightly shut. That is because while your epidermis naturally shuts out bacteria, it does let the tiny chlorine particles through.

If you are interested in the science behind that, you should know that chlorine’s 35.4 molecular weight is practically undetectable by your skin, which normally only aims to stop particles that are about 85 times heavier than that. As if that wasn’t enough, it can also freely enter your skin cells which tolerate molecules that are 21 times heavier, and even your blood which welcomes more than 4 times heftier molecules. Scientists claim that if we spend just 10 minutes in a pool, we may be taking in as much as two liters of chlorinated liquid. Indeed, you also take in a lot more chlorine from soaking in a pool than if you are merely showering with chlorinated water. This means that your blood will directly be taking it in, rather than a gradual, and, hopefully, partial absorption through the stomach. Additionally, if you happen to have low levels of iodine, you might even be ingesting more of the chlorine than you would be otherwise. As these two are both halides, your body will substitute iodine with chlorine, and absorb it at a faster rate than it normally would.

Want to check exactly how much chlorine you will take in from a pool you are about to enter? Bring a chlorine test kit with you and first test the chemical content of the water. Then proceed to stir the water in the cup with your finger for about a minute, at which point you should check its chlorine levels once more. You should be seeing quite a different chlorine content than the first time around. Where did it all go? Into your skin, of course.

Chlorine’s Effects On Your Internal System

Let’s face it – chlorine is a chemical. This fact, in itself, contradicts the possibility that it is a completely harmless substance. Indeed, exposure to chlorine has been not only been linked to skin issues, but also to various illnesses and conditions. For instance, research from the last decade has connected the chemical to a 0.45 higher-than-normal possibility of bladder cancer6. Generally, it has been suggested that chlorine could be killing the good bacteria in your intestines, while increasing the amounts of yeasts such as candida. When you take chlorine in (for example, from swallowing some of it while swimming), you could be risking nutrient imbalance, intestinal infection, increased intestinal permeability, etc. Chlorine has also been blamed for inborn fetal disorders, stillbirths and miscarriages. Regardless of whether or not your body is truly vulnerable to such serious ailments due to chlorine, the fact that the chemical could potentially cause such problems should be a sign that you do not want its inflammatory properties anywhere near your skin!

More Unintended But Inevitable Effects Of Chlorine

Did you know that as much as a quarter of US citizens urinate while swimming in public pools?  Surely the number is even larger, but most people would probably be embarrassed to come clean about it. That alone should turn you off from going for a swim in those infested baths. Still, if you are willing to risk it at this point, just read until the end of this section. Urine responds to the chlorine in pools, forming cyanogen chloride, which is actually the basis for various chemical weapons. It is therefore poisonous when it comes to your organs and it can very well kill a human being. When it comes to acne, cyanogen chloride causes recurring inflammation, which means that your skin will have a higher tendency to become irritated over and over again – leading to ongoing breakouts.

Naturally, the amounts of this compound that are formed in a pool are not nearly large enough to affect you in this way, but it’s still something to think about. Even though a swimming pool’s ingredients won’t kill you, they can cause other troubles such as inflammation. After all, chemical weapons are prohibited by international law! Indeed, this is only one of the countless disinfection byproducts that can result from chlorine’s presence in pools. These byproducts are typically a consequence of the reaction of chlorine7 with organic substances, such as bodily fluids. The terrifying part? Each and every swimming pool is unique in regards to its byproducts. This is because every pool’s contents differ depending on a myriad of factors. If you were to come to suffer from any of the listed ailments, including acne, you could never actually find out exactly what caused it.

A pool can also cause you to become a victim of cancerous haloacetic acids. These acids also increase your body’s susceptibility to all kinds of inflammation. An experiment found8 that all of its 49 test subjects of all ages tested positive for these acids between half an hour and three hours after coming into contact with them. By ‘coming into contact’ we don’t necessarily mean swimming in the pool – some of the subjects were merely standing close by and became victims of the substance by breathing it in. Granted, the swimmers sported four times more haloacetic acids, but children, for instance, took it in much faster than adults. Scary stuff, right?

Another kind of byproduct that you may be faced with are the various issues related to your reproductive system that result from the availability of trihalomethanes in pools, and even in some drinkable water. These enter your body through your respiratory system and can cause problems9 ranging from miscarriage to cancer. In regards to acne, trihalomethanes decrease your glutathione which is an antioxidant you need for the cleansing of your cells.

What Can You Do To Protect Yourself?

If we were to recommend for you to never set foot in a pool again, you will most probably not take our advice. After all, most people picture a fun time by a swimming pool when they think of their perfect summer day. Therefore, if you dare to still frequent public pools, the easiest thing you can do to protect yourself is to take showers as soon as you exit the water. You might also want to regulate the iodine in your system. As mentioned, if you have a healthy amount of iodine in your organism, then the chlorine you ingest will be a lot less than otherwise. Increase your iodine by consuming more fish, eggs and dairy. Additionally, high levels of iodine will also somewhat guard you from the other two redundant halides – fluoride and bromine.

On the other hand, if you happen to own a private pool, throw away all your chlorine and opt for iodine, instead. This is a pricier option but it does disinfect water equally well and carries far fewer risks than chlorine. You could also go for a saline salt pool, although this only serves to produce its own chlorine, albeit after some time.

If you are looking for public places to swim freely, without the burden of constantly fearing the water you are in, try to take a longer trip to the seaside, instead. Not only does saltwater not contain chlorine, but its minerals could benefit your skin (unless you have really sensitive skin – but you would probably already know that). If you are up for a longer vacation, and are looking for water that will truly rejuvenate your skin, opt for a trip to the Dead Sea, which is full of healthful minerals. If the sea happens to be too far from your location, you might also want to jump for a swim into a lake.

Should you be worried? You have, after all, survived your entire life while happily bathing in chlorinated swimming pools. If getting rid of acne is your main priority, or if you have extremely sensitive skin, then you should stray far from pools. If, on the other hand, you are only slightly worried about your skin and you love hanging out in a swimming pool, then you can continue to do so, as long as you shower your body thoroughly after exiting.


  1. Li J., Wang Z., Zhu X., Deng Z., Cai C., Qiu L., Chen W., Lin Y. Health Effects from Swimming Training in Chlorinated Pools and the Corresponding Metabolic Stress Pathways. PLoS One. 2015.
  2. Black A.P., Kinman R.N., Keirn M.A., Smith J.J., Harlan W.E. The disinfection of swimming pool waters. I. Comparison of iodine and chlorine as swimming pool disinfectants. American Journal of Public Health and the Nation’s Health. 1970;60(3):535–545.
  3. Fernández-Luna Á., Burillo P., Felipe J.L., del Corral J., García-Unanue J., Gallardo L. Perceived health problems in swimmers according to the chemical treatment of water in swimming pools. European Journal of Sport Science. 2016;16(2):256-65.
  4. Seki T., Morimatsu S., Nagahori H., Morohashi M. Free residual chlorine in bathing water reduces the water-holding capacity of the stratum corneum in atopic skin. The Journal of Dermatology. 2003;30(3):196-202.
  5. Chowdhury S. Predicting human exposure and risk from chlorinated indoor swimming pool: a case study. Environmental Monitoring and Assessment (Journal). 2015;187(8):502.
  6. Villanueva C.M., Cantor K.P., Grimalt J.O., Malats N., Silverman D., Tardon A., Garcia-Closas R., Serra C., Carrato A., Castaño-Vinyals G., Marcos R., Rothman N., Real F.X., Dosemeci M., Kogevinas M. TBladder cancer and exposure to water disinfection by-products through ingestion, bathing, showering, and swimming in pools. American Journal of Epidemiology. 2007;165(2):148-56.
  7. Kim H., Shim J., Lee S. Formation of disinfection by-products in chlorinated swimming pool water. Chemosphere (Journal). 2002;46(1):123-30.
  8. Cardador M.J., Gallego M. Haloacetic acids in swimming pools: swimmer and worker exposure. Environmental Science & Technology. 2011;45(13):5783-90.
  9. U.S. National Library of Medicine. Chlorine. Toxicology Data Network. Accessed 2019.
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