Swimming and your eyes: what really causes the redness, and how to protect them in pools and the sea

Published 9 September 20266 min read

The line everyone repeats when they climb out of a pool with red eyes is that the chlorine was strong today. That line is wrong almost every time. Chlorine at its correct concentration barely irritates the eye. What actually stings are compounds formed when chlorine reacts with what people carry into the water with them: sweat, skin oils, product residue and urine. Put more plainly, the pool that burns your eyes is not an over-disinfected pool, it is a pool that needs more disinfectant. That distinction is not a matter of wording, because it completely changes what you should do about it. The answer is not to avoid well-treated pools, but to protect the eye surface from the water itself, to favour places that keep their water balanced, and to respect the one absolute rule that is never bent: water must never get between a contact lens and your eye. This guide covers what happens to your eyes in water, how to choose goggles that genuinely hold, what to do after you get out, and when redness is more than passing irritation.

What happens to the eye surface in water

The eye is protected by a thin tear film of water, lipids and proteins that keeps the surface smooth, vision clear, and microbes from taking hold. Open your eyes underwater and that film is washed away within seconds, leaving the surface bare and far more vulnerable to irritation and to anything floating in the water. On top of that, pool water matches neither the salt concentration nor the acidity of tears, so water is drawn into or out of the surface corneal cells. That is the source of the temporary haze and the halos around lights straight after a swim. The haze usually clears within minutes to an hour and is not lasting damage in itself, but it is a clear signal that the eye surface has met something it was not built for. Sea water does something similar by a different route: it is far saltier than tears, which is why the sting is sharper in the moment even though it is chemically cleaner.

The stinging and redness mostly come from chloramines, formed when disinfectant reacts with organic dirt, rather than from chlorine itself.
A sharp chlorine smell in an indoor pool is a sign of water that needs better treatment and ventilation, not of excessive disinfection.
Haze and halos after swimming come from the cornea taking up water, and usually settle on their own within a short time.
A quick shower before getting in reduces the organic load in the water, and is the single most effective collective step for cutting irritation for everyone.

Goggles: choosing a pair that actually holds

Goggles are the real solution rather than a luxury, because they preserve the tear film and keep water off the eye surface altogether. Yet most people who complain about goggles bought a size that does not match their face. The practical test is simple: press the two eyecups onto your eye sockets without the strap. If they hold for a second or two by suction, the size is right; if they drop immediately, the gaskets do not match your face shape and no amount of strap tension will fix it. Over-tightening the strap is a common mistake — it does not compensate for a poor fit, it leaves marks around the eyes and can press on soft tissue. Fogging is another problem badly handled: the lenses carry an internal anti-fog coating that wiping destroys, so the worst thing you can do to your goggles is rub the inside with a finger or a towel. Rinse them in clean water after use and let them air-dry away from direct sun.

Test the suction before buying: the cups should hold on your face for a moment with no strap if the size is right.
Never wipe the inside of the lens: wiping strips the anti-fog layer and turns a new pair into a permanently fogged one.
For outdoor swimming choose a dark or mirrored lens with full UV protection, since the water surface reflects extra light.
If you need vision correction, swim goggles come in ready-made approximate powers, with fully custom prescription options available through opticians.
For children, a proper child-sized fit matters more than the brand: a leaking pair makes a child reject the water itself, not just the goggles.

Contact lenses and water: the rule that is never broken

This is the most serious point in the whole subject and deserves stating without softening: do not swim, shower, or sit in a hot tub while wearing contact lenses. A lens traps water between itself and the cornea and acts as an incubator for whatever lives in it. The headline risk is a parasite found in fresh water, tap water and pools that causes a rare but intensely painful corneal infection which is difficult to treat and can leave permanent marks on vision. That organism resists the chlorine levels normally used in pools, so a clean pool does not remove the risk. The second issue is that soft lenses absorb water, swell and stick to the cornea, and forcing them off at that point scratches the surface and opens the door to a further infection. If you want to see clearly in the water, the answer is prescription swim goggles, not a contact lens under a pair of goggles. And if you do end up in the water in lenses unavoidably, take them out as soon as you get out, throw them away, and do not return them to the case.

No water on a lens ever: not pool, sea, shower, tap water for rinsing, nor storage in plain water.
If you truly must wear them in water, use daily disposables and bin them the moment you get out — harm reduction, not a safe option.
Severe pain out of proportion to how the eye looks after swimming in lenses is a sign for urgent assessment, not for waiting.
Prescription swim goggles are the correct alternative, available either in near-enough ready powers or made to your prescription.

Sun over water: half the light arrives from below

A water surface is a strong reflector of ultraviolet light, which means anyone beside an open-air pool or on a beach takes a dose from above and a second one bouncing up from below eye level — the direction a hat and your brow never cover. Pale sand adds to it, as does any bright surface around a pool. Heavy exposure during peak hours can cause what amounts to sunburn of the cornea: a painful surface inflammation that appears hours later as fierce burning, watering and light sensitivity, usually healing within a day or two but thoroughly miserable while it lasts. Over years, accumulated exposure contributes to well-recognised changes on the eye surface and to earlier clouding of the lens inside the eye. Sensible protection is not complicated: sunglasses that block ultraviolet completely, with relatively large or wrapped lenses that cover from the sides, a brimmed hat, and less open sitting during the middle of the day.

Ultraviolet protection is independent of how dark the lens is, and a dark lens without it is worse than wearing nothing.
Children are more exposed because the lens inside their eye is clearer and passes more light, so protecting them poolside is not fussiness.
Polarised lenses noticeably cut the glare reflected off the water and are more comfortable for anyone spending long periods beside it.
Burning, pain and watering that begin hours after a long day on the water follow a known pattern, and deserve assessment if they do not improve within two days.

After you get out: what soothes the eye and what harms it

The first reaction of a swimmer emerging with red eyes is to rub them, and that is the worst possible move: the corneal surface is swollen and fragile at that moment and rubs scratch it easily. The alternative is straightforward — rinse your face with clean water with your eyes closed, then use preservative-free artificial tears to rebuild the watery layer and flush whatever is clinging to the surface. A cool compress on the closed lids for a few minutes eases redness and puffiness. Avoid whitening drops that work by constricting blood vessels; they flatter the appearance without treating the cause, and with repeated use the redness returns worse than before. Normally the eye settles within an hour to a few hours. What is not normal is redness lasting beyond a day, real pain rather than mere stinging, blurred vision that does not clear, purulent discharge, or severe light sensitivity. That cluster does not wait, and needs a specialist look.

Do not rub your eyes after swimming however much they itch: the surface is at its easiest to scratch right then.
Preservative-free artificial tears and a cool compress are enough in the great majority of simple irritation.
Whitening drops are a cosmetic stopgap; relying on them masks the problem and worsens redness when you stop.
Redness beyond a day, or pain, reduced vision or purulent discharge, are signs for examination rather than watchful waiting.

Frequently asked

Can pool water pass on an eye infection?+

It can, but not in the way people picture. A well-maintained pool with an appropriate disinfectant level kills most bacteria and viruses within minutes, and the commonest transmission around pools is not through the water but through everything beside it: shared towels, hands, borrowed goggles, and surfaces touched after rubbing an eye. The water itself becomes a risk when its balance is neglected or the place is crowded without adequate treatment, and that is when clusters of irritation and infection appear. The important exception is the parasite that causes corneal infection and resists ordinary chlorine, whose practical risk is almost entirely confined to people swimming in contact lenses. So the useful rules are: your own towel and goggles, wash your hands afterwards, do not rub your eyes, and never get in wearing lenses.

My child refuses to wear swim goggles at all. What can I do?+

In most cases the refusal is about the fit, not the idea. An adult-sized pair on a small face leaks, presses on the nose and leaves marks around the eyes, so the child associates goggles with discomfort. Start with a genuine child size, test the suction on their face before buying, then set the strap to be secure rather than tight, and let them wear the pair dry at home for a few minutes before the first time in water. The second half is psychological: let them pick the colour themselves so the goggles are theirs rather than imposed. Avoid putting them on in a tense moment, or pushing them to duck under on the first attempt. If they still refuse, the most valuable win is teaching them not to open their eyes underwater and not to rub afterwards, with artificial tears if things get irritated, until they come round to goggles gradually.

Can I just swim in my normal prescription glasses?+

It is neither practical nor safe. Ordinary glasses do not stay put once you are moving in water; the first knock or jump loses them, and searching the bottom is usually a losing game. More importantly, everyday lenses and frames are not built to resist impact in a crowded environment, and breakage close to the eye is a genuine risk not worth taking. Water also degrades some coatings over time, and chlorine and salt leave their mark on metal frames. The purpose-built alternative is prescription swim goggles, which come in two forms: ready-made approximate powers that cover most mild to moderate short-sightedness, or goggles made to your prescription when there is a big difference between your eyes or significant astigmatism. If you swim as a sport rather than for leisure, the made-to-prescription version earns its cost.

When is red eye after swimming a reason to worry?+

Redness that starts as you get out and gradually improves over an hour to a few hours, with mild stinging and passing haze, is expected irritation and needs nothing more than artificial tears, a cool compress and some rest. What warrants a specialist look is redness persisting beyond a day without improvement, genuine pain in the eye rather than surface stinging, blurring that does not clear when you blink, light sensitivity severe enough to stop you opening the eye in a lit room, sticky yellow discharge, or obvious lid swelling. And one situation tolerates no delay at all: severe pain after swimming in someone who was wearing contact lenses in the water. That is assessed urgently, because early diagnosis changes the outcome substantially in corneal infection.