Sunscreen and Your Skin Microbiome: What Is the Real Story?
We have spent decades being told to protect our skin from the sun. Now science is asking a much bigger question: what happens to the living ecosystem on our skin when we do?
For years, the sunscreen conversation has been remarkably simple.
Sun exposure damages the skin.
UV radiation causes premature ageing.
Too much ultraviolet radiation increases the risk of skin cancer.
Therefore, apply sunscreen.
There is certainly good evidence that excessive UV exposure damages skin and that sensible sun protection has an important role in reducing UV-related damage.
But there is another story emerging.
Your skin is not simply a piece of inert tissue sitting between you and the outside world. It is a living ecosystem populated by bacteria, fungi, viruses and other microorganisms. Together, these organisms form the skin microbiome.
And researchers are only now beginning to understand how important this microbial community may be to maintaining healthy skin.
The question is therefore becoming much more interesting:
What does sunscreen do to the skin microbiome?
And perhaps even more importantly:
What does sunlight do to the skin microbiome in the first place?
The emerging research suggests that we should stop thinking about this as a simple argument of "sunscreen is bad" or "sunscreen is good".
The real story is considerably more complicated.
Your skin is alive – and covered in microorganisms
Most people think of bacteria as something that needs to be eliminated.
That is an understandable idea when we are talking about infectious bacteria.
But the vast majority of microorganisms living on and in our bodies are not simply enemies waiting to make us sick.
The skin microbiome is part of our normal biology.
Different areas of the body have different microbial communities. The bacteria living on the oily skin of the face are not necessarily the same as those living in the dry skin of the forearm or the moist areas of the body.
These microorganisms interact with the skin, its immune system, its barrier and the chemicals produced at the skin surface.
Some produce metabolites that can influence skin cells. Others compete with potentially harmful organisms. Some interact with the immune system.
In other words, healthy skin is not necessarily sterile skin.
It is an ecosystem.
And ecosystems depend on balance.
Recent research is increasingly investigating the relationship between the skin microbiome, the skin barrier and the way the skin responds to environmental stresses such as ultraviolet radiation. [1][2]
Then we have sunlight
Here is where the story becomes particularly interesting.
We have traditionally thought of UV radiation almost exclusively in terms of its effect on human cells.
UV damages DNA.
UV generates oxidative stress.
UV contributes to inflammation and photoageing.
UV contributes to skin cancer.
All of these are important considerations.
But microorganisms living on the surface of our skin are exposed to exactly the same environment.
They are also being exposed to sunlight.
And UV radiation can affect microorganisms.
Research now suggests that UV exposure can change the composition and behaviour of the skin microbiome.
Some microorganisms are more sensitive to UV than others.
Others appear to be remarkably resistant.
This means that sunlight may act as a kind of environmental selection pressure, changing which microorganisms survive and which become less abundant.
A 2025 review of the emerging research described the relationship between solar radiation and the skin microbiome as an important but still developing area of science. The authors highlighted evidence that UV exposure can alter microbial composition and potentially influence the skin barrier and immune response. [3]
This changes the conversation.
We should not simply ask:
"Does sunscreen affect the microbiome?"
We should also ask:
"Does preventing UV exposure protect the microbiome?"
And this is where some of the research becomes rather surprising.
Sunscreen may not be the enemy of your microbiome
One of the most interesting findings is that sunscreen can sometimes protect the skin microbiome from UV exposure.
In a 2024 human pilot study, researchers exposed skin to an erythemal dose of UV radiation and compared areas treated with sunscreen with areas that received a placebo formulation without UV filters.
The researchers found associations between sunscreen treatment and particular microorganisms, including Lactobacillus crispatus, and concluded that sunscreen treatment could protect aspects of the skin microbiome from UV exposure. [4]
That is important.
Because it means the simplistic argument that:
sunlight = natural and therefore good
while
sunscreen = artificial and therefore bad
doesn't hold up particularly well.
The biology is more complicated.
UV radiation itself can alter microbial communities.
Sunscreen can prevent some of that UV exposure.
Therefore, under certain circumstances, sunscreen may actually help preserve parts of the microbiome.
But that does not mean that every sunscreen is microbiome-friendly.
And this is where we need to start looking much more carefully at the formulation.
Not all sunscreens are the same
"Sunscreen" is not one ingredient.
It is a formulation.
Different products can contain completely different UV filters, preservatives, emulsifiers, fragrances, stabilisers and other ingredients.
Some UV filters have demonstrated antimicrobial effects in laboratory studies.
Some other ingredients used in cosmetic formulations may also affect microorganisms.
A 2024 review examining the available evidence concluded that some UV filters and other sunscreen components can affect skin microbes, while also noting that the evidence remains limited and that the effects vary considerably between formulations. [1]
This distinction is crucial.
It is entirely possible for one sunscreen formulation to have little measurable effect on the resident microbiome while another formulation affects particular organisms.
So asking:
"Does sunscreen damage the microbiome?"
may actually be the wrong question.
The better question is:
"How does this particular sunscreen formulation interact with the particular microbial ecosystem living on my skin?"
That is a much harder question to answer.
And science is only beginning to do so.
Mineral sunscreens add another interesting piece to the puzzle
One of the more recent human studies looked specifically at sunscreens containing titanium dioxide or zinc oxide.
Researchers tested the formulations against several common skin bacteria and then studied the skin microbiomes of 20 human volunteers.
The results were surprisingly reassuring.
After sunscreen application, the researchers found no significant changes in overall microbial diversity during the 24-hour observation period.
The core microbial communities remained stable, and the tested bacteria did not show loss of viability after short-term exposure. [5]
This is an important finding because it challenges another simplistic narrative:
"Putting sunscreen on your skin must wipe out your good bacteria."
The evidence does not support that conclusion.
At least for the mineral formulations examined in this particular study, the skin microbiome demonstrated considerable resilience.
But there is another important qualification.
The study looked at relatively short-term exposure.
We still need considerably more research examining what happens with repeated daily application over months and years, across different formulations and different skin types.
That is the research gap that matters.
Your microbiome may actually help your skin deal with sunlight
Perhaps one of the most fascinating developments in this field is that scientists are beginning to ask whether the relationship works in both directions.
We know that sunlight affects the microbiome.
But could the microbiome also influence how our skin responds to sunlight?
There is growing evidence suggesting that it might.
Microorganisms produce metabolites and other compounds that can interact with skin cells and influence inflammation, immunity and the skin barrier.
Some microorganisms may even possess mechanisms that help them tolerate UV radiation.
Research on people exposed to substantial sunlight has identified changes in particular microbial populations, while laboratory work has suggested that certain skin bacteria may produce compounds capable of helping to reduce oxidative stress. [6]
This is an exciting area of research.
It suggests that our skin microbiome may not simply be an accidental collection of bacteria sitting on the surface.
It may form part of the skin's environmental defence system.
Think of it as another layer of biology between you and the outside world.
The next generation of sunscreen may need to protect two things
This could eventually change the way sunscreen is designed.
Until now, the primary question has been:
How effectively does this product protect human skin from UV radiation?
The next generation of products may need to ask another question:
How effectively does it protect the skin while preserving the microbial ecosystem living on it?
Researchers are already discussing the possibility of "microbiome-friendly" sunscreens.
Rather than simply blocking UV radiation, future formulations could potentially be designed to:
-
protect the skin from excessive UV exposure
-
minimise unnecessary disruption of beneficial microorganisms
-
preserve microbial diversity
-
support the skin barrier
-
work alongside naturally occurring skin microorganisms
-
potentially incorporate microbial metabolites or microbiome-supportive ingredients
This concept is already appearing in the scientific literature surrounding next-generation suncare. [2][3]
In other words, the future of sunscreen may not be about killing everything on the skin.
It may be about protecting the skin while respecting the ecosystem that lives there.
But here is where we need to be careful
There is a tendency in the health and wellness world to take emerging research and immediately turn it into a definitive conclusion.
We should resist that temptation.
The science surrounding sunscreen and the skin microbiome is still relatively young.
Some studies suggest sunscreen can alter microbial communities.
Other studies suggest particular sunscreens can preserve the microbiome during UV exposure.
A recent study involving mineral sunscreens found no significant short-term disruption of the skin microbiome.
Another small 2024 study examining a particular sunscreen formulation found no evidence that it induced the type of dysbiosis associated with acne. [7]
So the evidence does not currently justify saying:
"Sunscreen destroys your skin microbiome."
Nor does it justify saying:
"Sunscreen has absolutely no effect on your microbiome."
Both statements go further than the evidence.
The more accurate conclusion is much more interesting:
The skin microbiome is affected by UV radiation, sunscreen formulations can interact with skin microorganisms, and different formulations may have very different effects.
We need more long-term human research to understand the consequences.
This is why the ingredients matter
If you are concerned about your skin microbiome, it may be worth moving beyond the simple question of SPF.
SPF tells you something important about protection against UVB-induced sunburn.
Broad-spectrum protection tells you more about protection across UVA and UVB.
But neither tells you everything about how a formulation interacts with your skin ecosystem.
The full ingredient list matters.
The type of UV filters matters.
The preservatives matter.
The formulation matters.
And your own skin matters.
Two people can use the same product and experience very different outcomes.
This is one of the fundamental lessons we are learning from microbiome research generally:
Biology is individual.
There is no single "normal" microbiome that looks exactly the same in every person.
What about washing the sunscreen off?
There is another part of this conversation that deserves more attention.
If we start thinking of our skin as an ecosystem, then the question becomes bigger than sunscreen.
What happens when we apply sunscreen?
Then cleanser.
Then exfoliant.
Then toner.
Then antibacterial products.
Then retinoids.
Then moisturiser.
Then another layer of sunscreen.
Then we wash everything off and start again the next morning.
Modern skincare can involve an extraordinary number of interactions with the skin.
And every one of those products has the potential to influence the skin's microbial environment.
This is one reason the microbiome revolution in skincare is so important.
The question isn't simply:
"What should I put on my skin?"
It is also:
"What am I repeatedly removing from my skin?"
Your skin does not necessarily need to be sterilised
This is perhaps the biggest change in thinking.
For decades, cleanliness has often been associated with eliminating microorganisms.
But microbiome science has taught us that the goal is not necessarily to eliminate bacteria.
The goal is to maintain an ecosystem capable of supporting health.
That means we need to distinguish between harmful microorganisms and the enormous community of organisms that normally live with us.
Your skin is not supposed to be sterile.
Your gut is not supposed to be sterile.
Your mouth is not supposed to be sterile.
And your skin microbiome is not supposed to be sterile.
Health is much more about balance, diversity and resilience than simply eliminating every microorganism we can find.
And this brings us back to the gut
If you have been following the research into the gut microbiome, this should sound familiar.
The skin has a microbiome.
The gut has a microbiome.
The mouth has a microbiome.
These microbial ecosystems communicate with their host tissues and immune system in complex ways.
The emerging concept of the gut–skin axis suggests that what happens inside the body can influence the skin, while the skin itself represents an enormous interface between the body and its environment.
This does not mean that taking a probiotic automatically fixes a skin condition.
That would be far too simplistic.
But it does mean that skin health cannot necessarily be separated from the rest of the body's biology.
The better we understand the microbiome, the harder it becomes to view the body as a collection of isolated organs.
So should you stop using sunscreen?
No.
That is not what the current evidence says.
Excessive UV exposure is a genuine threat to skin health, and sunscreen remains one component of sensible photoprotection.
The emerging microbiome research does not overturn that.
Instead, it adds another layer to the conversation.
We should be asking whether the products we use can protect the skin without unnecessarily disturbing its natural microbial ecosystem.
That is a much more intelligent question than simply declaring sunscreen either "good" or "bad".
And it is a question that researchers are now actively investigating.
The real story is bigger than sunscreen
The most exciting thing about this research isn't discovering whether sunscreen is a friend or enemy of your microbiome.
It is discovering that the skin itself is an ecosystem.
For years, we focused almost entirely on the skin cells.
Now we are beginning to understand the organisms living alongside those cells.
And the relationship between them may be far more important than we previously realised.
UV radiation can change the microbial environment.
Some sunscreen ingredients can affect microorganisms.
Some sunscreen formulations may help preserve the microbiome by preventing UV damage.
Other formulations may have little measurable effect.
And the microbiome itself may contribute to the skin's ability to respond to environmental stress.
The science is still developing.
But one thing is becoming increasingly clear:
The future of skincare will not be about simply protecting the skin from the outside world. It will be about understanding and supporting the living ecosystem that helps the skin function in the first place.
Perhaps the next generation of sunscreen will not simply say:
"Protects your skin from the sun."
Perhaps it will say:
"Protects your skin — and respects the microbiome that lives on it."
That is where the science is heading.
And that is a far more interesting story than simply asking whether sunscreen is good or bad.
The evidence behind the story
[1] Grant GJ, Kohli I, Mohammad TF. A narrative review of the impact of ultraviolet radiation and sunscreen on the skin microbiome. Photodermatology, Photoimmunology & Photomedicine, 2024.
[2] Mercer SD, McBain AJ, O'Neill CA. The Skin Microbiome, Microbial Metabolites and the Epidermal Response to Ultraviolet Radiation—Towards Next Generation Suncare. Experimental Dermatology, 2025.
[3] Gilaberte Y et al. Exploring the impact of solar radiation on skin microbiome to develop improved photoprotection strategies. Photochemistry and Photobiology, 2025.
[4] Schuetz R et al. Sunscreens can preserve human skin microbiome upon erythemal UV exposure. International Journal of Cosmetic Science, 2024.
[5] Smith ML et al. The human skin microbiome remains unchanged after 24 h of sunscreen application. Applied and Environmental Microbiology, 2025.
[6] Research into skin bacteria enriched following prolonged sun exposure has identified microorganisms with potential protective effects against UV-associated oxidative stress.
[7] Arantes AB et al. Facial dysbiosis and UV filters. Archives of Dermatological Research, 2024.