Sea Water, Sun and Chlorine for Eczema: What the Trials Show
and it points somewhere unexpected. Dilute bleach baths are a recognised adjunct for atopic dermatitis,
and NIAMS lists a diluted bleach bath twice a week among treatments, with the warning that you should not
use it without first talking to your doctor. But a 2017 meta-analysis of five studies found that at four
weeks, bleach baths and plain water baths performed the same: EASI fell from 24.9 to 11.0
in the bleach group and from 25.2 to 14.2 in the water group, with no significant differences
observed between them. The authors concluded bleach baths are effective in reducing severity but
do not appear more effective than a water bath alone. So the bathing is doing the work. For sun, NIAMS
notes doctors may use ultraviolet A or B light waves for severe cases, which is controlled phototherapy
rather than a beach holiday. For sea water specifically, we found no comparable trial evidence and have
not printed any.
Almost everyone with eczema has noticed that something about water changes it, and the internet is full
of confident explanations: the sea heals it, chlorine ruins it, sunshine clears it. The trial evidence is
narrower than any of those claims and more interesting than all of them.
Start with chlorine, because the answer is backwards
The intuition is that chlorine is harsh and dries out eczema. In dermatology, dilute sodium hypochlorite
is an established adjunctive treatment, and the National Institute of Arthritis and Musculoskeletal and
Skin Diseases lists a diluted bleach bath twice a week among things that may help treat
atopic dermatitis.
NIAMS attaches an unambiguous condition to that:
You should not use this treatment without first talking to your doctor.
That is not boilerplate. Concentration matters, and the concentrations used in research are very dilute:
published protocols describe roughly half a cup of household bleach in half a tub of warm water, producing
a solution in the region of 0.005% to 0.009% sodium hypochlorite. This is a measured medical intervention,
not an instruction to add bleach to a bath.
Then the finding that reframes the whole question
A systematic review and meta-analysis published in Annals of Allergy, Asthma & Immunology
in 2017 (PMID 29150071) pooled five studies, with 18 to 40 patients per trial, comparing dilute bleach
baths against plain water baths.
At four weeks, measured by EASI, the eczema area and severity index:
- Bleach group: 11.0 ± 7.8, down from a baseline of 24.9 ± 25.3
- Water bath group: 14.2 ± 7.7, down from a baseline of 25.2 ± 12.3
Both groups improved substantially. And then the line that matters:
There were no significant differences observed between bleach vs. water baths.
The authors’ conclusion: while bleach baths are effective in reducing AD severity, they do not appear to
be more effective than water bath alone.
What that implies for the sea
Read the two arms of that trial again. A regimen of regular baths in plain water, in
people with moderate to severe atopic dermatitis, roughly halved the severity score over four weeks.
Nobody adds anything. The water alone did that.
Which is worth holding in mind when someone reports that their skin improved dramatically on a beach
holiday. On that holiday they were bathing daily, in warm water, often with more consistent moisturising
afterwards, in a humid climate, while less stressed and better rested than usual.
The sea is the salient variable because it is the memorable one. It is not necessarily the operative one,
and the bleach trial is a clean demonstration that people routinely credit the additive when the bathing was
doing the work.
To be explicit about the limits of that reasoning: this is not evidence that sea water does nothing. It
is evidence that a plain water bath does a lot, which raises the bar for what any additive has to
demonstrate. We looked for controlled trial evidence on sea water specifically for eczema and did not find
comparable data, so we are not printing a figure for it.
Sun: the medical version is not the holiday version
NIAMS states that for severe cases doctors may recommend ultraviolet A or B light waves
to treat symptoms.
That is real, and it is phototherapy: specific wavelengths, measured doses, delivered in a clinical
setting with the exposure escalated carefully and the cumulative total tracked.
Sitting on a beach is a different intervention with the same active ingredient and none of the controls.
The wavelength mix is not selected, the dose is not measured, and the outcome you are risking is sunburn,
which damages the skin barrier that eczema treatment is trying to protect.
So the honest answer to “is sun good for eczema” is that ultraviolet light is used as a treatment under
supervision, and that the supervised version is what has evidence behind it.
What NIAMS actually recommends for bathing
This is the part with the least glamour and the most support, and it is specific:
- Lukewarm baths to cleanse and moisturise the skin without drying it excessively
- Limit baths to once a day
- Mild unscented bar soap or non-soap cleanser
- Pat the skin dry after bathing, and do not allow it to get too dry before moisturising
- Moisturise to seal in the water absorbed during bathing
Note the mechanism in that last point. The bath is not just cleaning; it is loading the skin with water,
and the moisturiser is there to stop it leaving. That is why the timing matters and why moisturising an hour
later is a different act from moisturising immediately.
Two things NIAMS says to avoid
Irritants and rough clothing, such as wool.
Lotions with high water or alcohol content, which can cause burning.
That second one deserves attention because it cuts against the instinct to reach for something light and
fast-absorbing when skin feels hot. A high-water, high-alcohol lotion evaporates, and on broken skin it
stings for a reason.
How to read the products people ask about
Search behaviour around eczema is dominated by brand names: which soap, which cream, which cleanser. The
guidance above answers those questions at the level of properties rather than brands: mild,
unscented, non-soap or gentle bar, low alcohol.
Any product meeting that description is doing what the guidance describes, and any product failing it is
not, regardless of what the packaging says about sensitive skin. That is a more durable test than a brand
ranking, because formulations change and the properties do not.
Frequently Asked Questions
Is salt water good for eczema?
We could not find controlled trial evidence for sea water specifically, so this page does not give a
figure for it. What the evidence does show is that plain water baths alone produced substantial improvement:
in the water bath arm of a 2017 meta-analysis, EASI fell from 25.2 to 14.2 over four weeks. If your skin
improves at the coast, regular bathing, humidity, consistent moisturising and lower stress are all changing
at the same time, and the trial evidence suggests the bathing itself is a strong candidate for the effect.
Is chlorine bad for eczema?
Not in the way most people assume. Dilute sodium hypochlorite baths are a recognised adjunct in atopic
dermatitis and NIAMS lists a diluted bleach bath twice a week among treatments. That said, a 2017
meta-analysis of five studies found no significant differences between bleach baths and plain water baths at
four weeks, so the added chlorine did not demonstrably improve on water. Swimming pool chlorine is a
different exposure again, uncontrolled in concentration and paired with drying, and is not what those studies
tested.
Should I try a bleach bath at home?
Not without asking your doctor, and NIAMS states that directly: you should not use this treatment without
first talking to your doctor. Concentration is the whole issue. Research protocols use extremely dilute
solutions, in the region of 0.005% to 0.009% sodium hypochlorite, made by adding roughly half a cup of
household bleach to half a tub of water. Getting that wrong on inflamed, broken skin is a real risk, and the
meta-analysis suggests the upside over a plain bath is not established anyway.
Does sunshine help eczema?
Ultraviolet light is used as a treatment, and NIAMS notes doctors may recommend ultraviolet A or B light
waves for severe cases. That is phototherapy: selected wavelengths, measured doses, clinical supervision and
tracked cumulative exposure. Unsupervised sun exposure delivers the same active ingredient without any of
those controls, and carries a sunburn risk that damages the skin barrier eczema treatment is trying to
restore.
How often should I bathe if I have eczema?
NIAMS advises lukewarm baths to cleanse and moisturise without drying the skin excessively, and to limit
baths to once a day. The key detail is what happens afterwards: pat the skin dry rather than rubbing, and
moisturise before it gets too dry, in order to seal in the water absorbed during the bath. The bath is
loading the skin with water and the moisturiser is what keeps it there.
What soap should I use?
NIAMS describes the property rather than the product: mild unscented bar soap or a non-soap cleanser.
That is the useful test to apply to any brand you are considering, because it survives reformulation in a way
that a product recommendation does not. It also rules out a large share of what is marketed for sensitive
skin, since fragrance is common even in products positioned that way.
Why do lotions sometimes sting?
NIAMS specifically advises against lotions with high water or alcohol content, noting they can cause
burning. This runs against the instinct to use something light and quick-absorbing on hot, irritated skin. A
high-alcohol, high-water lotion evaporates rather than sealing, and on broken skin the stinging is a signal
rather than an inconvenience.
Does any of this replace prescribed treatment?
No. Everything on this page is supportive care around the medical treatment of atopic dermatitis, which is
a condition with real prescription options that this article does not cover. Bathing and moisturising
routines are part of standard management rather than an alternative to it, and if your eczema is moderate or
severe, the treatments with the strongest evidence are the ones your doctor prescribes.
Sources
- Chopra R, Vakharia PP, Sacotte R, Silverberg JI. Efficacy of bleach baths in reducing severity of atopic
dermatitis: A systematic review and meta-analysis. Annals of Allergy, Asthma & Immunology, 2017.
PMID 29150071. Five studies, 18 to 40 patients per trial; at four weeks EASI 11.0 ± 7.8 versus baseline
24.9 ± 25.3 in the bleach group and 14.2 ± 7.7 versus baseline 25.2 ± 12.3 in the water bath group; no
significant differences observed between bleach versus water baths; conclusion that bleach baths are
effective in reducing AD severity but do not appear more effective than water bath alone —
Full text - NIAMS, Atopic Dermatitis: Diagnosis, Treatment, and Steps to Take: lukewarm baths limited to once a day;
mild unscented bar soap or non-soap cleanser; patting skin dry and moisturising before it gets too dry to
seal in absorbed water; a diluted bleach bath twice a week with the instruction not to use it without first
talking to your doctor; ultraviolet A or B light waves for severe cases; avoiding irritants and rough
clothing such as wool; avoiding lotions with high water or alcohol content which can cause burning. Checked
August 2026 —
niams.nih.gov - NIAMS, Atopic Dermatitis overview: environmental contributors including tobacco smoke, certain air
pollutants, fragrances and other compounds in skin products and soaps, and excessively dry skin —
niams.nih.gov
Figures above are taken from the published meta-analysis abstract and
from NIAMS guidance, checked August 2026. Where no controlled trial evidence could be located for a specific
exposure, such as sea water, no figure is printed rather than a number being supplied from elsewhere.
