Have you ever switched from one cleanser, serum or moisturiser to another, only to find that your skin still feels sensitive, looks red or becomes itchy?
For people with eczema-prone, reactive or acne-prone skin, even choosing a new moisturiser, sunscreen, foundation or concealer can feel like a gamble. Will it trigger redness, an eczema flare-up or another acne breakout? That constant uncertainty can take much of the freedom and enjoyment out of skincare and make-up.
Why do some people have plenty of stubborn blackheads or whiteheads, yet rarely develop inflamed acne, while others cleanse diligently, follow a careful skincare routine and still face one breakout after another?
And why can some people regularly experiment with new skincare and cosmetics without experiencing redness or irritation, while others use very few products, choose only “natural” options and still find that their eczema returns whenever the seasons change?
When something goes wrong with our skin, most of us look for the answer on its surface. We cleanse more deeply, add another serum, try a stronger exfoliant or cover the problem with make-up.
This is particularly familiar to people with eczema-prone or highly reactive skin, for whom redness, dryness and itching may affect both comfort and confidence. Eczema affects as many as one in five children and one in ten adults in the UK.¹
Yet the visible skin is only one part of a much bigger biological picture. What if an important part of the story begins much deeper inside the body?
Your Skin Does Not Work Alone
The skin is often described as the body’s largest organ, but it is easy to think of it as little more than a covering. In reality, it is a living, renewing and highly active barrier. Skin cells are continually produced, replaced and repaired. The skin helps retain water, regulates temperature and forms a physical defence against irritants, allergens, pollutants and microorganisms.
It also works closely with the immune system. Immune cells within the skin constantly monitor what is happening around them. When they detect injury, infection or another potential threat, they release chemical signals that coordinate inflammation and repair. This response is essential. It helps prevent a small cut from becoming infected and allows damaged tissue to heal.
The reaction, however, needs to match the situation. A well-regulated response deals with the problem and then begins to settle. A poorly regulated response may become too intense, continue for too long or react strongly to something that would ordinarily cause little difficulty.
This helps explain why two people can encounter a similar external trigger but experience very different skin reactions.
Why Can a Blocked Pore Stay Quiet for Years—While a Tiny One Becomes Inflamed?
Acne provides an everyday example of how something visible on the surface can involve a much deeper response underneath.
Blackheads and whiteheads both begin when sebum and dead skin cells accumulate inside a hair follicle. With a blackhead, the follicle remains open. Its dark colour comes from material at the surface reacting with oxygen, rather than trapped dirt. A whitehead, also known as a closed comedone, forms when the opening of the follicle is sealed. Sebum and dead skin cells remain beneath the surface. Both are usually described as non-inflammatory comedones because they can remain present without obvious redness, swelling or pain.
This is what makes some extraction videos on social media so fascinating—and rather puzzling. A surprisingly large plug may be removed from a pore that has apparently remained quiet for years, with hardly any redness around it.
Meanwhile, someone else may cleanse carefully, have very few visible blackheads and still experience repeated breakouts. A tiny closed bump that was barely noticeable yesterday may become red, swollen and painful today.
The size of the blockage is therefore only part of the story. Hormones, sebum composition, skin-cell turnover, the condition of the follicle wall, Cutibacterium acnes and the local immune response all help determine what happens next.²
When inflammatory activity develops around the follicle, a quiet blockage can become a red papule, a pus-filled pustule or, in more severe cases, a deeper nodule.² This is also why stronger cleansers and more frequent scrubbing cannot fully explain—or resolve—the difference. Excessive cleansing may irritate the skin barrier while leaving the biological processes inside the follicle unchanged. Squeezing may release some of the contents and make a spot appear flatter, but it can also damage the follicle and increase the risk of prolonged inflammation, dark marks or scarring.
Our skin contains a vast number of hair follicles and pore openings. However clear or healthy somebody’s skin may appear, occasional blackheads, whiteheads and minor blockages are a normal possibility. The more interesting question is this: what makes the surrounding skin remain calm in one situation but sound the inflammatory alarm in another?
Keep that question in mind. The same clue also helps explain redness, soreness and itching.
Why Can a Small Irritant Leave Skin Red, Sore and Itchy?
Some people rarely experience acne yet regularly develop patches of skin that become red, dry, sore or itchy. The symptoms may resemble a mild eczema-like reaction that comes and goes. For others, they may form part of diagnosed eczema or psoriasis.
Why can a little sweat, dry weather, fragranced skincare, laundry detergent, pet hair or dander—or even the change from one season to another—produce such a noticeable reaction?
One reason involves the skin barrier. When the barrier becomes weakened, more water escapes from the surface. The skin becomes drier and more permeable, allowing irritants, allergens and microbial substances to enter more easily. The immune system detects these changes and begins sending messages. Scientists call many of these chemical messengers cytokines. Some cytokines tell nearby cells to start or amplify inflammation, while others help coordinate, balance and calm the response.
When inflammation is activated, blood vessels in the affected area widen and more immune activity is directed towards the skin. This can contribute to visible redness, warmth, swelling and soreness.
In eczema, inflammatory messengers including interleukin-4 and interleukin-13 can reduce the production of proteins that help maintain a strong skin barrier. Another messenger, interleukin-31, can communicate with sensory nerves, contributing directly to the sensation of itching.³
This can create a frustrating self-reinforcing cycle:
Inflammation → weakened skin barrier → dryness and greater exposure to irritants → itching → scratching → further barrier damage → more inflammation
Scratching may provide a moment of relief, but it also causes tiny injuries to an already vulnerable barrier. The skin then becomes more exposed, more inflamed and even itchier.
Psoriasis also involves excessive inflammatory activity, although its immune pathways differ from those involved in eczema. In psoriasis, immune signals encourage skin cells to renew much more rapidly than usual, contributing to the raised, inflamed and scaly plaques associated with the condition.
Whether the result is an angry spot, an itchy eczema flare-up or a psoriasis plaque, the visible problem reflects more than the original blockage or irritation. The intensity and duration of the immune response help determine what eventually appears on the skin.
The Missing Link: Immune System's Overreaction, But Why?
We can now bring these examples together:
- One person may have a large blackhead that remains visibly calm, while another develops an inflamed spot from a much smaller blockage.
- One person may encounter an irritant with only brief discomfort, while another develops redness, soreness and itching that continue long after the original exposure.
The missing link is inflammation—and, more specifically, how the immune system decides when to start it, how strongly to amplify it and when to calm it down.
Inflammation is part of the body’s protection and repair system. It brings immune cells and other resources to an area where there may be injury, infection or danger. Problems arise when the alarm is triggered too easily, becomes louder than the situation requires or continues after its useful work should be complete.
In acne, hormones, sebum, follicular blockage, skin microorganisms and the condition of the follicle wall all shape the immediate reaction. In eczema, genetics, barrier weakness, allergens, irritants and microbial exposure are important. Psoriasis follows its own combination of genetic and immune influences. The immune response helps connect these different factors to the redness, swelling, soreness and itching that we eventually see and feel.
So, would stronger immunity automatically give us healthier skin?
By now, the answer should be clear: immune strength alone is not the goal. The healthiest immune response is appropriately judged, rather than simply as strong as possible. Think of the immune system as a well-trained security team. Its job is to recognise genuine threats and respond quickly, while remaining calm around harmless visitors, food components, ordinary environmental exposures and the microorganisms that normally live on and inside the body. An overenthusiastic security team might sound the alarm every time somebody approaches the door. In the same way, an easily triggered immune response may turn a relatively small blockage or irritant into a much larger inflammatory event. For healthy skin, immune balance and immune judgement are every bit as important as defence.
But where does the immune system learn how to make these distinctions?
One of its most important training grounds is the gut.
Meet the Gut–Skin Axis
The digestive tract is home to trillions of microorganisms, including bacteria, viruses and fungi. This community is known as the gut microbiota, while the term gut microbiome also includes their genes, functions, activities and surrounding environment. These microorganisms do much more than help with digestion. They interact continually with the gut lining and immune cells. They break down food components that our own enzymes cannot fully digest, produce a wide range of metabolites and provide a steady stream of molecular signals to the immune system. This regular contact contributes to what scientists sometimes describe as immune education or immune training. The gut microbiota helps shape how the immune system develops, functions and distinguishes ordinary exposure from genuine danger.⁴
Some microbial signals encourage defence when it is needed. Others contribute to the checks, balances and calming signals that help prevent an immune response from becoming unnecessarily intense or continuing for too long. Rather than simply “boosting” or “suppressing” immunity, the gut microbiome contributes to an immune system that can react, regulate itself and return towards balance.
The gut and skin may be physically far apart, but messages created in the gut can interact with the immune system and travel through the circulation. Certain gut microorganisms also ferment dietary fibre to produce metabolites, including short-chain fatty acids, which can support the gut lining and take part in immune regulation. Changes in the gut microbial community, its metabolites or the condition of the intestinal barrier may therefore influence the wider inflammatory environment in which the skin operates.⁵˒⁶
This interconnected relationship between the gut microbiome, immune system and skin is known as the GUT-SKIN AXIS.
Researchers have observed differences in gut microbial communities in people with acne, atopic eczema and psoriasis, although each condition also involves its own combination of genetic, hormonal, environmental, microbial and skin-related factors.⁵⁻⁸ The gut cannot explain every individual spot or flare-up. However, the gut–skin axis reveals a broader explanation for how the body’s internal environment may influence whether the skin remains calm or reacts more intensely.
When Modern Living Changes the Conversation
The gut microbiome is remarkably adaptable, but it is also highly responsive to the way we live. Diet, stress, sleep, physical activity, smoking, alcohol, illness, medication and antibiotic exposure can all influence the composition or activity of the gut microbiome over time.⁹
A busy urban lifestyle can easily create several of these pressures at once:
- meals low in fibre and plant variety;
- frequent reliance on highly processed convenience foods;
- long periods of sitting;
- irregular sleep;
- ongoing psychological stress;
- social drinking or smoking; and
- courses of medication or antibiotics when medically necessary.
The overall pattern matters far more than one late night or occasional takeaway meal. Habits repeated over time have greater potential to shape the gut environment.
To explore these influences in more detail, read Why Modern Living May Be Affecting Your Gut Health and Well-being.
Dietary variety deserves particular attention because different plant foods provide different fibres and natural plant compounds for gut microorganisms to work with.
Colour can be a useful reminder to bring more variety to the plate, even though the benefits come from the foods and nutrients themselves rather than colour alone.
You can learn more in What Is the Rainbow Diet? The Science Behind Colour, Variety and Gut Health.
The Takeaway
Why can one person have stubborn blackheads and whiteheads for years without developing much inflamed acne, while somebody who cleanses carefully and follows a diligent skincare routine experiences one breakout after another?
Why can one person experiment freely with different skincare and cosmetics, while another chooses only gentle or “natural” products and still develops redness, itching or an eczema flare-up whenever the seasons change?
The blockage, product or irritant is only the beginning of the story. What happens next also depends on how the skin barrier and immune system interpret the situation—whether they remain calm, produce a proportionate response or sound an inflammatory alarm that becomes louder and lasts longer than necessary.
Many of us respond to skin problems entirely from the outside. We cleanse more deeply, buy increasingly expensive or “natural” skincare, avoid make-up altogether or use cosmetics to conceal redness and breakouts.
External skincare remains important, particularly for protecting the skin barrier and avoiding known irritants. Appropriate medical treatment also remains essential for persistent or severe acne, eczema, psoriasis and unexplained itching.
Yet the skin never works in isolation. The gut microbiome helps educate the immune system, produces metabolites from components of our diet and contributes to the wider inflammatory environment in which the skin operates. Diet, gut health and the balance of the gut microbial community may therefore form an often-overlooked part of the skin-health picture. This communication between the gut microbiome, immune system and skin is the GUT-SKIN AXIS. Understanding it gives us a more complete way to view our skin concerns: caring for what appears on the outside while also paying attention to the internal environment that may shape how strongly the skin reacts.
Sometimes, looking after the skin begins with what we put on it.
But sometimes, an important part of the answer may begin in the gut.
References
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Furue M, Ulzii D, Vu YH, Tsuji G, Kido-Nakahara M, Nakahara T. Pathogenesis of atopic dermatitis: current paradigm. Iran J Immunol. 2019;16(2):97-107. doi:10.22034/IJI.2019.80253.
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Mahmud MR, Akter S, Tamanna SK, Mazumder L, Esti IZ, Banerjee S, et al. Impact of gut microbiome on skin health: gut-skin axis observed through the lenses of therapeutics and skin diseases. Gut Microbes. 2022;14(1):2096995. doi:10.1080/19490976.2022.2096995.
Kim JE, Kim HS. Microbiome of the skin and gut in atopic dermatitis (AD): understanding the pathophysiology and finding novel management strategies. J Clin Med. 2019;8(4):444. doi:10.3390/jcm8040444.
Sikora M, Stec A, Chrabaszcz M, Knot A, Waskiel-Burnat A, Rakowska A, et al. Gut microbiome in psoriasis: an updated review. Pathogens. 2020;9(6):463. doi:10.3390/pathogens9060463.
Valdes AM, Walter J, Segal E, Spector TD. Role of the gut microbiota in nutrition and health. BMJ. 2018;361. doi:10.1136/bmj.k2179.