The Skin Barrier and Skin Microbiome: What They Mean for Persistent Skin Problems
Updated: 1 day ago
The skin barrier is the outermost layer of your skin. It holds water in, keeps irritants out and is home to a community of microorganisms known as the skin microbiome. When the barrier is damaged, skin can feel tight, dry, stinging or reactive, and products that used to suit you may start to sting.
Persistent problems such as acne, eczema and rosacea each involve the barrier and the microbiome in different ways, alongside genetics, hormones, the immune system and lifestyle. Understanding which of these matter for you is often more useful than adding another product.
I'm Marina Kostadinova-Yankova, an NMC-registered nurse, and I run Juvenology Clinic in Maidstone, Kent. The sections below cover what the skin barrier and microbiome are, how to recognise a damaged barrier and help it repair, how far the new microbiome research goes, and when a skin concern needs your GP or a dermatologist.
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The skin microbiome: the microorganisms that live on your skin
Probiotics, prebiotics, postbiotics and live-microbe skincare
BIOJUVE, Dr Thomas M. Hitchcock and "living skin biome care"
Acne, eczema and rosacea: why one explanation does not fit every condition
Looking beyond skincare: hormones, lifestyle and wider health
What is the skin barrier, and why does it matter?
The skin barrier mainly sits in the stratum corneum, the thin outer layer of skin. It is often compared to a brick wall: flattened, protein-rich cells are the bricks, and the lipids between them, mainly ceramides, cholesterol and free fatty acids, are the mortar. [1] This structure limits how much water escapes from the skin and helps keep irritants and microorganisms out. [1]
When the barrier works well, skin stays comfortable and hydrated. When it is disrupted, more water is lost and irritants get in more easily, which can lead to dryness, inflammation and sensitivity. A disturbed barrier plays a part in several skin conditions, including contact dermatitis, psoriasis and atopic eczema. [1] That does not mean every skin problem is a barrier problem, as the condition sections below explain.
Signs of a damaged skin barrier, and what causes it
"Damaged skin barrier" is not a medical diagnosis, but it is a useful way to describe skin that has become irritated and less resilient. Common signs include:
skin that feels tight, dry or rough, or flakes
stinging or burning when you apply products that used to be fine
redness, which may look dark brown, purple or grey on darker skin [4]
itching or a patchy, uneven texture
Stinging, burning and itching in response to things that would not normally cause them are the hallmarks of what dermatologists call sensitive skin. The skin can look normal or slightly red. [2]
Common causes include:
Harsh cleansing and scrubbing. The NHS advises against scrubbing skin with acne because it can irritate it and make acne worse. [3]
Irritants. Contact dermatitis is most commonly caused by irritants such as soaps, detergents, solvents and regular contact with water. [4]
Too many active ingredients. Acids and retinoids can irritate the skin. NICE advises starting some topical acne treatments on alternate days or for short periods to reduce irritation. [5]
If your skin is cracked, weeping, painful, or not improving after you remove a likely trigger, see your GP. The NHS advises seeing a GP for persistent, recurrent or severe contact dermatitis. [4]
How to help a damaged skin barrier repair itself
There is no single product that "fixes" the barrier, but simple changes give it the best conditions to recover:
Simplify. Pause exfoliating acids, scrubs and other actives until your skin is comfortable again, then reintroduce one at a time.
Cleanse gently. Use a mild, non-soap cleanser and lukewarm water. For acne-prone skin, NICE recommends a non-alkaline cleanser, neutral or slightly acidic, twice a day. [5]
Moisturise. Moisturisers work in different ways. Occlusive ingredients form a layer that reduces water loss, humectants help the outer layer of skin hold water, and ceramides help restore barrier function. [6]
Protect from the sun with a daily broad-spectrum sunscreen.
Introduce new products one at a time, so you can tell which ones your skin tolerates.
If your skin keeps reacting despite a simple routine, there may be another explanation, such as eczema, rosacea, an allergy or a medicine you are using, and it is worth having it assessed.
How long does a damaged skin barrier take to repair?
There is no fixed timescale, and the figures quoted online vary. Recovery depends on what caused the damage, whether that cause has been removed and whether a skin condition is involved. The NHS says contact dermatitis usually improves or clears up completely once the substance causing it is identified and avoided. [4]
The skin microbiome: the microorganisms that live on your skin
The skin is home to bacteria, fungi and other microorganisms, collectively called the skin microbiome. Most are normal residents, not infections. Which organisms live where depends on the environment: oily areas such as the face and back are dominated by Cutibacterium (formerly Propionibacterium), moist areas such as skin folds by Staphylococcus and Corynebacterium, and dry areas such as the forearms have the most diverse communities. [7]
Resident microorganisms appear to have useful roles, including helping to protect against harmful organisms and interacting with the skin's immune system. [7, 8] The relationship between microbes, the barrier and the immune system is complex, and there is no single "healthy microbiome" that applies to everyone. The presence of a particular microorganism does not automatically mean it is causing harm.
Probiotics, prebiotics, postbiotics and live-microbe skincare
Skincare marketing uses these terms loosely, but they have specific scientific definitions:
Term | What it means | Example in skincare |
Probiotic | Live microorganisms that, in adequate amounts, give a health benefit [9] | Products containing live bacteria |
Prebiotic | Something that resident microorganisms use selectively, giving a health benefit [10] | Ingredients intended to "feed" beneficial microbes |
Postbiotic | Inactivated microorganisms or their components that give a health benefit [11] | Heat-killed bacteria and lysates |
Strictly, a product only meets these definitions if a health benefit has been shown. Many products described as "microbiome-friendly" may not have been tested in that way. Do not try to culture or apply bacteria to your skin yourself.
BIOJUVE, Dr Thomas M. Hitchcock and "living skin biome care"
One example of how microbiome science is being turned into skincare is BIOJUVE, a skincare range from Crown Laboratories. Dr Thomas M. Hitchcock, a geneticist, is Crown's Chief Science Officer. [12, 13] He founded Xycrobe Therapeutics, which Crown acquired in 2019. [12, 24]
The idea behind it starts with a bacterium usually linked to acne. Cutibacterium acnes is a normal resident of oily skin, but it is not one uniform organism. It is divided into subspecies and many strains, which can behave differently. [14] A recent systematic review found that some strain types were more common in acne lesions and others in healthy skin. [8] That is why researchers increasingly talk about the balance of strains, rather than simply "acne bacteria".
Crown's Xycrobe technology uses a particular strain of C. acnes subspecies defendens [25], and the BIOJUVE regimen tested in published studies contains a live strain called XYCM42 together with a ferment produced by it. [14, 15] Laboratory work suggested the strain and its ferment may have antioxidant, anti-inflammatory and some antimicrobial activity. [14]
Juvenology does not sell BIOJUVE. It is discussed here as a research example, not as the only model for skin health or as a product every person needs.
What the clinical research does and does not tell us
We found three published clinical studies of the XYCM42 regimen. All three were funded by Crown Laboratories, and all or most of the authors work for the company. [14, 15, 16]
Study | Design | What was measured | Main findings | Limits |
Rhee et al. 2023 [14] | Laboratory work, a 3-week pilot (10 people) and an 8-week study (121 people, 32 assessed in clinic) | General skin health: hydration, redness, sebum | Authors report improved hydration and reduced redness | No comparison group described in the published summary |
Alqam et al. 2023 [15] | Randomised study of 40 adults with acne scars having four microneedling sessions; BIOJUVE versus standard skincare | Overall appearance, acne scar scores, safety | Greater improvement on a clinician-rated appearance scale between the 2- and 6-month visits; acne scar improvement not significantly different between groups at 2 months | Small; single centre run by the company; uneven drop-out; blinding not described; active, not placebo, comparison |
Alqam et al. 2025 [16] | 8-week study, 140 people with acne-prone skin enrolled (136 completed), no comparison group | Tolerability, irritation, acne lesions | No adverse events reported; no one reported worse acne | Designed to test safety, not to show it treats acne; authors say results are not conclusive |
Taken together, these studies suggest the regimen was well tolerated in the people studied, including those with acne-prone skin. They do not show that it treats acne, eczema or rosacea, and they have not been independently replicated or tested against a placebo product. An independent systematic review describes the evidence for probiotic approaches to acne as preliminary. [8]
Microbiome-based skincare may influence how skincare and aesthetic treatments are planned in future. For now, it is emerging science rather than established treatment.
Acne, eczema and rosacea: why one explanation does not fit every condition
These are different conditions with different biology, so neither the barrier nor the microbiome is a universal explanation.
Acne involves oil production, blocked hair follicles and inflammation; bacteria can grow in blocked follicles. [3] C. acnes is part of normal skin, and strain differences and microbial balance appear to matter. [7, 8] NICE says there is not enough evidence to support specific diets for treating acne. [5] Effective treatments are available from a GP [3], and acne that is causing scarring or persistent pigmentation may need referral to a dermatologist. [5]
Atopic eczema involves a weakened barrier, the immune system and genetic factors [1, 19]; changes in the filaggrin gene, which helps build the barrier, are a major risk factor. [17] During flares, Staphylococcus aureus tends to make up a bigger share of the skin's bacteria. [18] Eczema cannot be cured, but emollients and treatments prescribed by a GP help control it. The NHS advises not changing your diet unless a doctor tells you to. [19]
Rosacea causes facial redness, flushing and sometimes spots. Its cause is not known. Common triggers include alcohol, spicy food, hot drinks, sunlight, temperature changes, exercise and stress. [20] People with rosacea tend to have more Demodex mites on their skin, but there is no direct evidence that the mites cause it. [21] Rosacea cannot be cured, but a GP can help control the symptoms. Eye symptoms need urgent medical advice. [20]
Rather than looking for one hidden cause that applies to everyone, it is more useful to understand your own pattern of symptoms and make informed decisions about care from there.
Looking beyond skincare: hormones, lifestyle and wider health
Skin is influenced by more than what is applied to it. Depending on the person and the condition, relevant factors can include:
Hormones, which can play a part in acne, for example around periods or pregnancy. [3]
Stress, which the NHS lists as a trigger for both eczema and rosacea. [19, 20]
Genetics and family history, such as in eczema. [17]
Medicines and supplements, some of which can affect the skin.
Diet, where the evidence is more limited than many claims suggest.
Gut health and the skin. Researchers are investigating links between the gut microbiome and the skin, often called the gut–skin axis, but this work is at an early stage and the mechanisms are not yet fully understood. [22] Because the research is so new, it does not justify treating every persistent skin problem as a gut problem.
Be cautious with elimination diets. The NHS advises people with eczema not to change their diet unless a doctor tells them to. [19] For children with eczema, NICE advises that excluding a food should be tried only under dietary supervision when food allergy is strongly suspected, and that children with moderate or severe eczema and suspected food allergy should be referred to a specialist. [23] If you suspect a food allergy, a nutritional deficiency or a gut problem, see your GP.
A product-only routine or a personalised approach?
Product-based skincare has its place. The difference lies in how much is assessed before decisions are made.
Product-only routine | Personalised approach | |
Starting point | A concern and a product to target it | Your history, skin, routine and goals |
Previous products | Often added to, not reviewed | Reviewed for tolerance and overlap |
Barrier and sensitivity | May not be considered | Assessed before adding actives |
Lifestyle and health | Rarely discussed | Discussed where relevant |
Medical referral | Not part of the process | Considered when symptoms suggest it |
A hypothetical example. Someone with dull skin starts an exfoliating acid, a retinol serum and a vitamin C product in the same month. Their skin becomes red, tight and stinging, so they buy a stronger "repair" serum. A review of the routine might suggest pausing the actives, using a gentle cleanser and a simple moisturiser until the skin settles, and then reintroducing one product at a time. Here, removing products is more useful than adding another. This example is illustrative and does not describe a real client.
What a skin consultation can help you understand
At Juvenology, we consider appearance, skin health and how you feel together, because skin is shaped by more than age. Sleep, stress, hormones, diet and general health can all play a part. In practice, that means starting with an assessment rather than a product.
A skin consultation with me takes 30 minutes and costs £50. I look at your skin and talk through your history, current products, medicines and lifestyle. You leave with a plan, which may be a simpler home routine, an in-clinic treatment where appropriate, or a letter to your GP if your skin needs medical care. I do not diagnose skin disease or prescribe medicines. There is no obligation to buy any treatment or product. We do not offer microbiome testing.
If you have acne, eczema, psoriasis or rosacea, the condition pages explain what a consultation can and cannot help with. Our guide to personalised skincare advice explains what happens during an appointment.
Frequently asked questions
What is the skin microbiome?
The community of bacteria, fungi and other microorganisms that live on the skin. Most are normal residents, and the mix varies between oily, moist and dry areas. [7]
Why is the skin barrier important?
It limits water loss and helps keep irritants and microorganisms out. When it is disrupted, skin can become dry, irritated and sensitive. [1]
Will a damaged skin barrier heal on its own?
Often it settles once the cause is removed. The NHS says contact dermatitis usually improves or clears up completely when the trigger is identified and avoided. [4] Eczema and rosacea are different: they cannot be cured, but a GP can help control them. [19, 20]
Can an imbalanced skin microbiome contribute to acne?
Research suggests microbial imbalance and particular strains of C. acnes are involved, alongside oil, blocked follicles and inflammation. [8] It is one part of the picture, not the whole cause.
What is BIOJUVE, and what is Xycrobe technology?
BIOJUVE is a skincare range from Crown Laboratories. Xycrobe is the company's name for its technology based on a strain of C. acnes subspecies defendens. The BIOJUVE regimen in published studies contains a live strain, XYCM42, and its ferment. [14, 25]
Who is Dr Thomas M. Hitchcock?
A geneticist who is Chief Science Officer at Crown Laboratories and founded Xycrobe Therapeutics. He is an author of the company's XYCM42 studies. [12, 14, 15, 16]
Can skincare products affect the skin microbiome?
Yes. Acne treatments such as benzoyl peroxide have been shown to change microbial diversity. [8] Whether a given "microbiome-friendly" product benefits the skin depends on how it has been tested.
Is microbiome skincare scientifically proven?
Not yet. The XYCM42 studies are small, short and funded by the manufacturer, and an independent review calls the evidence for probiotic approaches to acne preliminary. [8, 14, 15, 16]
Can gut health affect the skin?
Researchers are investigating possible links, but the evidence is early. Do not cut out foods without medical or dietetic advice. [22, 23]
Why do persistent skin problems need individual assessment?
Acne, eczema, rosacea and irritated skin have different causes and triggers, and a product that helps one can aggravate another.
How does Juvenology approach skin health?
By starting with an assessment of your skin, history and lifestyle, explaining your options plainly, and involving your GP or a dermatologist when a concern needs medical care.
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If you would like to understand what is behind your skin's behaviour, you can book a skin consultation or start with a free discovery call on WhatsApp, which is not a clinical assessment.
About the author
Marina Kostadinova-Yankova is the founder of Juvenology Clinic in Maidstone, Kent. She is a registered adult nurse with the Nursing and Midwifery Council (NMC) and has more than 25 years of nursing experience. She trained in aesthetic medicine with Harley Academy and Derma Medical Academy, is listed with the Joint Council for Cosmetic Practitioners (JCCP) and is a member of the Aesthetic Complications Expert (ACE) Group. Read more about Marina.
This article is general information and does not replace individual medical advice. Speak to your GP about persistent, severe or worsening skin symptoms. Information was checked in October 2026.
