According to abc13.com,

Chlorine in swimming pools don't make your eyes red, it's the urine. Quoting from the article:

One of the most shocking revelations the CDC shared was the truth behind what causes your eyes to become red and irritated after swimming in the pool. And it's not the chlorine.

"It's quite the opposite," said Beach. "Chlorine binds with all the things it's trying to kill from your bodies, and it forms these chemical irritants. That's what's stinging your eyes. It's the chlorine binding to the urine and the sweat."

Is there any truth to this claim?

  • 4
    The easiest way to see if this is true would be to take a swim in your toilet and see what it does to yor eyes.
    – Neil Meyer
    Commented Jan 3, 2016 at 14:04
  • 1
    Perhaps partly confirmed by the abstract of a Chinese-American study "Volatile Disinfection Byproducts Resulting from Chlorination of Uric Acid: Implications for Swimming Pools". I don't have access to the publication to analyse its content so as to provide an answer to OP question.
    – Graffito
    Commented Jan 3, 2016 at 23:16
  • 2
    Good find! The OP talks about redness of eyes which is the most consistent symptom usually attributed to viral conjunctivitis along with irritation after a swim. The virus causing this is known to spread through direct contact via swimming pool water. Conjunctivitis can also be due to an allergic reaction to irritants such as chlorine or other chemicals used to disinfect swimming pools as explained in the answer below. Commented Jan 4, 2016 at 7:22
  • How about the fact that you can get red eyes from a pool that has never had anyone swim in it (just been chlorinated)?
    – warren
    Commented Jan 9, 2016 at 2:48

1 Answer 1


Yes, it is to a large extent.

This paper by Lian et al. explores the formation of volatile chlorinated compounds that are formed from reactions with organic nitrogen compounds, such as urea, amino acids, uric acid and creatinine.

The authors exposed both dilute solutions of uric acid and bodily fluid analogs (mixtures of compounds intended to mimic the composition of bodily fluids such as sweat and urine) to the sodium hypochlorite disinfectant used in swimming pools.

They showed by mass spectroscopy that uric acid, when exposed to sodium hypochlorite, forms the toxic compounds cyanogen chloride and trichloroamine, and the bodily fluid analogs also produce similar levels of these chemicals when exposed to sodium hypochlorite.

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They also showed that physically adding uric acid (simulating urination) into actual samples of pool water caused the levels of cyanogen chloride and trichloroamine to increase:

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The researchers conclude that:

Because uric acid introduction to pools is attributable to urination, which is largely a voluntary process for most swimmers, opportunities exist for significant improvement of air and water quality in pools via changes in swimmer hygiene practices. Specifically, if swimmers avoided urinating in pools, then air and water quality would likely improve independent of other changes in water treatment or air circulation.

  • 1
    I think "yes" is misleading. It is the result of a reaction between urine and chlorine. Urine alone won't do it. Chlorine alone won't do it. Commented Jan 6, 2016 at 15:08
  • 4
    @HelloWorld The answer completely matches the claim quoted in the question text.
    – March Ho
    Commented Jan 6, 2016 at 15:20
  • 1
    The answer is technically correct. But if one reads the question, "Is urine the cause of redness of eyes", and then reads the first line in your answer, then the initial impression one gets is incorrect. The first line should have conveyed this message: "It's the combination of urine and x, not urine." Commented Feb 24, 2016 at 12:06

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