The Skin Microbiome: What Is Established, and What Is Still Marketing
Your skin carries a large and varied population of bacteria, fungi and viruses, and that population is genuinely involved in skin health. That much is well established. What is not established is most of what is currently sold on the strength of it. This is an honest account of where the line sits, because the gap between what the research shows and what the label claims is unusually wide in this particular field.
Your skin carries a huge and varied population of bacteria, fungi and viruses, and that population really is involved in how healthy your skin is. That much is settled. What is not settled is most of what is currently being sold on the back of it. This is an honest account of where the line falls, because in this particular field the gap between what the research shows and what the label claims is unusually wide.
The Skin Microbiome: What Is Established, and What Is Still Marketing: the essentials
The short version
Skin carries a diverse microbial community that differs by body site
Your skin carries a mixed population of microbes, and it is different on different parts of your body.
That community interacts with the skin barrier and the immune system
Those microbes interact with your skin’s protective barrier and with your immune system.
Composition differs in conditions such as atopic dermatitis and acne
The mix is different in conditions such as eczema and acne.
That a cosmetic product can durably alter it in a way that improves an outcome
That a cosmetic product can change that mix for long, in a way that actually makes anything better.
Barrier care and anti-inflammatory treatment, which have good evidence
Looking after the skin barrier, and treating the inflammation. Both have good evidence behind them.
Ask whether the outcome measured was a symptom or a bacterial count
Ask what they actually measured: how you felt and looked, or just a count of bacteria.
What is actually living on you
What is actually living on you
Skin is not a uniform habitat. Oily areas such as the face and upper back favour different organisms from moist areas such as the elbow crease, which differ again from dry areas such as the forearm. The communities are stable enough to be characteristic of a site and variable enough to differ substantially between individuals.
Your skin is not one habitat. Oily areas such as your face and upper back suit different organisms from damp areas such as the crease of your elbow, and both are different again from dry areas such as your forearm. These populations are steady enough to be typical of a place on the body, and varied enough to differ a lot from one person to the next.
This is well documented, and it matters clinically in at least one clear way: the assumption that bacteria on skin are a problem to be eliminated is wrong. Cutibacterium acnes, for instance, is a normal resident of the follicle in almost everyone, including people with no acne at all. Its presence is not the disease.
This is well documented, and it matters in at least one clear way: the idea that bacteria on your skin are a problem to be wiped out is simply wrong. The germ most associated with acne, for example, lives in the pores of nearly everyone, including people who have never had a spot. Its being there is not the disease.
That single fact reframes a great deal. Acne is not an infection to be sterilised; it is an inflammatory condition in which the organism is one participant among four. It is why antibiotics help but do not cure, and why using them alone breeds resistance without solving the problem.
That one fact changes how you should think about a lot of this. Acne is not an infection to be sterilised. It is an inflammatory condition in which that germ is one player out of four. It is why antibiotics help but never cure, and why using them on their own teaches germs to survive without fixing the problem.
Where the evidence is good
Where the evidence is genuinely good
The strongest findings concern association and mechanism rather than treatment. In atopic dermatitis, the community shifts during flares, with a well-documented increase in Staphylococcus aureus, and the shift is closely linked to barrier disruption and inflammation.
The strongest findings are about what goes together, and why, rather than about treatments. In eczema, the mix of organisms shifts during a flare, with a well documented rise in one particular bacterium, and that shift is closely tied to a damaged barrier and to inflammation.
What follows from that, clinically, is not a probiotic. It is the treatment that already had the evidence: repair the barrier, control the inflammation, and the community tends to normalise as the skin does. In other words, the microbiome finding supports the existing treatment rather than replacing it.
What follows from that in the clinic is not a probiotic. It is the treatment that already had the evidence: repair the barrier, get the inflammation under control, and the mix of organisms tends to settle back down as the skin does. So the microbiome finding backs up the existing treatment rather than replacing it.
There is genuine research into more direct approaches, including bacteriotherapy for atopic dermatitis, and some of it is interesting. It is research. It is not something available on a shelf, and a cosmetic product referencing it is borrowing credibility from work that has not concluded.
There is real research into more direct approaches, including putting particular helpful bacteria onto eczema skin, and some of it is genuinely interesting. But it is research. It is not something on a shelf, and a cosmetic product that name checks it is borrowing credibility from work that has not finished.
Where the claims outrun the evidence
Where the claims run ahead of the evidence
The commonest gap is between changing a measurement and changing an outcome. A product may demonstrably alter bacterial counts on the skin for a period. Whether that alteration persists, and whether it makes anything better, are separate questions, and they are frequently not answered.
The commonest gap is between changing a measurement and changing your life. A product may well shift the bacterial counts on your skin for a while. Whether that shift lasts, and whether it makes anything better, are separate questions, and they usually go unanswered.
There is also a definitional problem. A probiotic is, strictly, a live organism administered in an amount that confers a health benefit. Most cosmetic products described as probiotic contain no live organisms, because keeping bacteria alive in a cosmetic emulsion is difficult and preservatives are designed to prevent exactly that. Many contain fragments or fermentation products instead, which may or may not do anything and are a different claim.
There is also a problem with the word itself. Strictly, a probiotic is a live organism given in an amount that does you some good. Most cosmetics described as probiotic contain no live organisms at all, because keeping bacteria alive in a cream is difficult and the preservatives in it are designed to stop exactly that. Many contain fragments, or the leftovers of a fermentation, instead. That may or may not do anything, and it is a different claim.
None of that makes these products harmful, and some are perfectly good moisturisers. The point is narrower: if a product improves your skin, it is worth knowing whether that is because of the microbiome mechanism on the label or because it is a well-formulated moisturiser, since the second is a much commoner explanation.
None of that makes these products harmful, and some of them are perfectly good moisturisers. The point is narrower: if a product improves your skin, it is worth knowing whether that is because of the microbiome story on the label, or because it is simply a well made moisturiser. The second is a much more common explanation.
What is actually worth doing
What is actually worth doing
The practical advice that follows from microbiome research is, slightly anticlimactically, the advice that was already good: do not over-clean, do not over-exfoliate, protect the barrier, and treat inflammatory conditions properly rather than trying to sterilise them.
The practical advice that comes out of microbiome research is, a little disappointingly, the advice that was already good: do not over clean, do not over scrub, look after the barrier, and treat inflamed skin properly rather than trying to sterilise it.
Harsh antibacterial cleansing, aggressive exfoliation and stripping surfactants all disturb both the barrier and the community that lives on it, and both take time to recover. That is a reasonable, evidence-supported use of the microbiome idea, and it costs nothing.
Harsh antibacterial washing, aggressive scrubbing and stripping cleansers upset both the barrier and the community living on it, and both take time to recover. That is a fair, evidence backed use of the microbiome idea, and it costs nothing.
If a skin condition is not settling, the useful step is a diagnosis rather than another product. Persistent redness, itch or rash has a cause, and the treatments with the strongest evidence are prescription ones aimed at that cause.
If a skin problem is not settling, the useful next step is a diagnosis rather than another product. Redness, itching or a rash that keeps going has a cause, and the treatments with the strongest evidence are prescription ones aimed at that cause.
Questions patients ask
Are microbiome skincare products worth buying?
Are microbiome skincare products worth buying?
Some are good moisturisers, and a good moisturiser is worth having. The specific claim that they improve outcomes by changing the microbiome is not currently supported by strong evidence in cosmetic products, so judge them as moisturisers.
Some of them are good moisturisers, and a good moisturiser is worth having. The specific claim that they help by changing the microbes on your skin is not currently backed by strong evidence in cosmetic products, so judge them as moisturisers.
Does washing my face destroy my microbiome?
Does washing my face destroy my microbiome?
Ordinary gentle cleansing does not cause lasting harm; the community recovers. Repeated harsh or antibacterial cleansing is a different matter, and it disturbs the barrier as well, which is the more immediate problem.
Ordinary gentle washing does no lasting harm, and the population bounces back. Repeated harsh or antibacterial washing is a different matter, and it damages your barrier too, which is the more immediate problem.
Is the bacterium in acne something to be killed off?
Should the acne germ be killed off?
No. It is a normal resident of the follicle in people with and without acne. Treatment aims to control inflammation and blockage as well as bacterial activity, which is why antibiotics are paired with other agents and used for limited periods.
No. It lives in the pores of people with acne and people without it alike. Treatment aims at the inflammation and the blockage as well as at the germ, which is why antibiotics are given alongside other things and only for a set time.
Will microbiome treatments become real medicine?
Will microbiome treatments become real medicine?
There is active research, including in atopic dermatitis, and it may produce treatments. Whether it does, and for which conditions, is not yet known, and that uncertainty is worth stating plainly rather than presenting as imminent.
There is active research, including in eczema, and it may well lead to treatments. Whether it does, and for which conditions, is not yet known. That uncertainty is worth saying out loud rather than dressing up as just around the corner.
How do I evaluate a microbiome claim on a label?
How do I judge a microbiome claim on a label?
Ask what outcome was measured. A change in bacterial counts is a measurement; an improvement in dryness, itch or a rash is an outcome. Claims that report the first and imply the second are the ones to be careful with.
Ask what they measured. A change in bacterial counts is a measurement. Less dryness, less itching, or a rash clearing up is a result. Claims that report the first and let you assume the second are the ones to be careful with.
Talk it through with a physician first.
Every plan starts with an assessment of your skin, your anatomy and what you actually want to change.
This page is general health information, not medical advice. It cannot tell you whether a treatment is right for you. Approved uses, risks and results differ from person to person, and product labelling changes. Ask us at Dermatology and Laser Centre about your own situation, or make an appointment, and seek urgent care for any serious symptom.
