Skin Microbiome 101

Written by Megan Falk: Experienced health and wellness journalist and editor. Megan is a graduate of Syracuse University’s S.I. Newhouse School of Public Communications, where she earned a bachelor’s degree in Magazine Journalism and a minor in Food Studies. She’s also a certified personal trainer through the American Council on Exercise.
Reviewed by Jennie O’Grady: Senior SciComms Specialist at Seed Health. Dr. O’Grady is a trained clinician with a background in clinical research and expertise in physiology and the microbiome. With certifications in nutrition science and microbial science, she is passionate about educating audiences in the latest research on health, wellness, and advancements in the microbiome.

The next time you’re tempted to buy a viral cleanser, serum, or exfoliant in pursuit of a smooth, “filter-like” complexion, remember this: The most important determinant of skin health can’t be seen on the surface. It’s invisible to the naked eye.

Meet your skin microbiome. This unseen shield defends the largest organ of your body from UV rays, pathogens, and toxic substances. It safeguards your internal organs, prevents dehydration, and even helps dictate your immune response. And yes, it impacts your skin’s texture, tone, and appearance, too. 

Here’s your game plan for building a strong, resilient, and balanced skin microbiome—no intensive facials or pricey regimens required.

What Is the Skin Microbiome?

The skin microbiome is the collection of microorganisms that reside on and in the three main layers of human skin (epidermis, dermis, and hypodermis).^1,2 

More than 600 species of microbes have been identified in this ecosystem, including 174 new-to-science species of bacteria as well as a cadre of mostly harmless fungi and viruses.³ 

The skin microbiome forms an invisible shield between you and your environment, preventing harmful substances and chemicals from penetrating your body. 

If you were to map out your entire skin microbiome from head to toe, you’d find a highly varied topography. Regions of dry skin, such as the forearms and palms, tend to have greater microbial diversity than more oily (or “sebaceous”) areas like the face and back.^4,5 Under a microscope, these sites can be “likely as ecologically dissimilar as rainforests are to deserts,” researchers say.⁴

The skin’s thickness, lipid content, and density of hair follicles and glands can all affect the types of microbes that are able to survive on it.

Outside of major changes such as puberty, the composition of the skin microbiome tends to remain generally stable.⁶ However, the degree of stability varies depending on the body part. The skin on your foot, forearm, and behind your knee, for example, tends to be more diverse and likely to change over time.^4,6 

How the Skin Microbiome Impacts Whole-Body Health

You can think of skin microbes as boots-on-the-ground soldiers protecting you from intruders and sounding the alarm whenever potential threats approach. Here are just a few reasons this microbial landscape is so essential:

1. It helps fight infection and manage inflammation: Beneficial microbes can create a slightly acidic skin environment that is not conducive to the growth of many pathogenic bacteria.⁵ They can also produce or trigger the release of antimicrobial peptides that further inhibit harmful species’ growth.^5,7 Furthermore, your skin microbes are lucky enough to have a direct communication line to your immune cells. This means that once they come in contact with a potential threat, they’re able to help modulate how your immune system reacts to it.⁸ Commensal (good) bacteria can signal immune cells to maintain a balanced response, reducing inflammation and preventing overactions that can lead to skin conditions (more on those below).
2. It speeds up wound recovery: When disruptions do occur on the body’s surface, a resilient skin microbiome can help us recover from them. Some species of bacteria, such as Lactobacillus reuteri, may expedite wound healing by modulating the immune response, reducing inflammation, and promoting tissue repair.^9,10
3. It helps prevent UV damage: Other beneficial bacteria promote skin resilience and produce antioxidants that fend off damage from UV radiation.¹¹ 
4. It can improve skin hydration and appearance: The skin microbiome also interacts with your sebaceous glands to regulate oil (aka sebum) production and skin pH. Hello, hydrated complexion.^5,12,13 
5. It may play a role in skin cancer prevention: Certain strains of Staphylococcus epidermidis bacteria may even be protective against skin cancer.¹⁴ Based on mice studies, this microbe seems to produce a molecule that can inhibit melanoma and other cancer cells while sparing benign cells. Though more research needs to be done, it is thought that about 20% of people carry this cancer-protective strain of S. epidermidis.

Signs of a Disrupted Skin Microbiome

When the balance of beneficial and harmful microbes on your skin is disrupted, your skin microbiome enters a state of dysbiosis. This impacts the skin’s ability to maintain a strong and resilient barrier.¹⁵ 

The changes associated with dysbiosis can potentially trigger or worsen skin issues like the following:

• Acne: While the exact causes and development of acne are not fully understood, there is evidence that microbes play a role in the condition. Microbial communities on your skin interact with sebaceous glands to regulate oil production and support hydration. When this balance is disrupted, acne can happen. One key player is Cutibacterium acnes, a bacterium that primarily lives within hair follicles and relies on sebum as a primary nutrient source.^5,12 More sebum equals more food, potentially leading to an overgrowth of C. acnes—certain strains of which can contribute to acne and trigger inflammation.¹⁶ That said, acne is often caused by a mix of genetic, immune, and environmental factors, in addition to microbial ones.¹⁷ (For example, as many of us are painfully aware, during puberty, sex hormones trigger the development of the sebaceous glands which can lead to breakouts.¹⁶)
• Atopic Dermatitis (AD): Atopic dermatitis (aka eczema) is linked with overall declines in microbial diversity on the skin and a notable increase in Staphylococcus aureus. This overgrowth of S. aureus overwhelms commensal microbiota and can, in turn, exacerbate inflammation and skin damage. (In general, the less microbial diversity, the more severe the AD symptoms.)¹⁸
• Psoriasis: Psoriasis vulgaris typically affects drier spots of skin, such as the elbows and knees. Although research is mixed, some studies suggest that dysbiosis of the skin microbiome may play a role in the chronic condition.¹⁸ Specifically, areas with psoriatic lesions may have a different balance of certain bacteria compared to skin that is not inflamed.¹⁹ 
• Rosacea: Microscopic mites like Demodex folliculorum are usually found at the base of the eyelashes. Despite their sinister-sounding name, they’re usually harmless. However, in folks with rosacea, these tiny bugs seem to collect on facial skin.²⁰ In high numbers, D. folliculorum mites can harbor bacteria that can trigger inflammation and redness.²¹ The presence of certain microorganisms, including Staphylococcus epidermidis and Cutibacterium acnes, has also been linked to rosacea, potentially due to their activation of the innate immune system.²²

One important caveat: While research has shown that changes in the microbiome are associated with certain skin conditions, we don’t yet know the precise role of each microorganism in skin health, or how to treat these conditions via the skin microbiome.²³

How Can I Tell If Mine Is in Good Shape?

Skin microbiome testing is one way to learn more about your microbial makeup. Though convenient, at-home testing kits may not provide a complete, accurate representation of the entire skin microbiome.

Your skin microbiome is a diverse ecological landscape, so if you take samples only from the surface of one or two areas, your results won’t reflect a complete view of the microbiome. (That’s like saying an animal as unique as a manatee can be found in waters across the U.S. just because you saw one in Florida.) 

The collection process is also flawed: The skin has a relatively low microbial load compared to other parts of your body, so it’s tough to get enough DNA for analysis.²⁴ Results can vary depending on the type of tool used (say, a swab vs. a sticky tape or a scraping tool), and there’s a risk of contamination when you gather and send in your sample. 

Testing services also lack a universally accepted standard for skin microbiome analysis. This means your results could vary from service to service.²⁵

Even if your results do accurately reflect your skin microbiome, there’s not enough scientific research yet to credibly link certain microbes with certain skincare tips or treatment plans. 

With this in mind, how can you tell if your skin microbiome is functioning as it should? For starters, you can get to know your baseline: What does your skin usually feel and look like? When you become acquainted with your personal “normal” (which is different for everybody), you’ll be able to pick up on when something’s off. 

That said, having smooth, hydrated, and less sensitive skin tends to be a sign your skin microbiome is in good shape. When yours veers out of balance (due to harsh skincare products, diet, stress, or other factors outlined below), you might notice issues like dryness, redness, irritation, or conditions like eczema. 

How to Support the Skin Microbiome

Supporting your skin microbiome is all about prioritizing practices that nurture its diversity and resilience. This doesn’t have to be complicated or expensive; just do your best to stick with the routines below.

Do: 

• Use gentle, low-pH products. Your skincare and cosmetics products shouldn’t disrupt the natural pH of the skin (roughly 4.5 to 5.5).²⁶ Many popular cleansers, soaps, and texturizers tend to have an alkaline pH ranging from 7 to 8, which can throw off the skin’s microbial balance. Instead, look for unscented, low-pH products (less than 5) that don’t contain antimicrobial preservatives. They’ll be less likely to disrupt microbial diversity—and they may actually positively impact the microbiome by reducing certain potentially pathogenic microbial populations.²⁷  
• Eat a balanced, plant-rich diet. Your gut-skin axis is a two-way telephone line between the gut microbiome and the integumentary system (the scientific term for your body’s outer layer, consisting of your skin, hair, nails, and some glands). Thanks to this axis, consuming plenty of fruits, veggies, and probiotics can help promote skin health and potentially ease acne and certain skin diseases (e.g., eczema and atopic dermatitis).^28,29
• Get outside. The ecosystem surrounding you influences the ecosystem within you. Researchers speculate that the microbiomes throughout your body (including on your skin) “pick up” some of the beneficial microbes you encounter in the outdoors—even through simple acts like touching or breathing in nature.³⁰ While the long-term microbiome benefits of this exposure are still being explored, getting outdoors has plenty of validated whole-body benefits too.

Don’t:

• Over-cleanse. Excessively washing your skin, especially with harsh cleansers, can strip it of its natural oils and beneficial microbes, disrupting the skin barrier and affecting pH. If you’re experiencing irritation, dryness, or tightness, that could be a sign of over-washing or using the wrong products for your skin.³¹ Chat with your healthcare provider or dermatologist for specific recommendations. 
• Sit in the sun without sunscreen. Excessive UV exposure can cause acute and chronic skin damage, including inflammation, premature aging, and increased cancer risk. UV radiation also disrupts the skin microbiome, potentially leading to dysbiosis and compromised skin barrier function.³² 
• Accept chronic stress as “normal”: Stress activates the hypothalamic-pituitary-adrenal axis, increasing the production of cortisol and other stress hormones. This hormonal response can cause inflammation and immune dysregulation, which may exacerbate skin conditions like psoriasis, eczema, and acne. Stress might also lead you to pick up not-so-healthy habits, like neglecting your skincare routines or eating a poor diet, that further disrupt the skin microbiome.^33,34

Frequently Asked Questions (FAQs)

• Why is the skin microbiome important? Though invisible to the naked eye, the skin microbiome plays a crucial role in many major bodily functions, including wound healing, maintaining skin hydration and integrity, and supporting immunity.
• How can I improve my skin microbiome? Don’t overthink it. Using gentle, lower pH skincare products, prioritizing time outdoors, and fueling yourself with fruits, veggies, and probiotic-rich foods can help you achieve a balanced, diverse skin microbiome without overhauling your routine.
• What disrupts the skin microbiome? Stress, excessive UV exposure, harsh antimicrobial skincare products, and over-cleansing can all cause disruptions to the skin microbiome. Due to the gut-skin axis, dysbiosis in the gut can cause negative changes to the skin microbiome.
• What foods help the skin microbiome? Fruits, vegetables, fiber-rich foods, and probiotic ingredients can enrich and regulate the gut microbiome, potentially supporting the skin microbiome too.

The Key Insight

Beauty isn’t just skin deep. The skin microbiome—with its vast impacts on your gut, mind, and immune system—proves it. Protect yours by using gentle, low-pH skincare products, prioritizing time outdoors, and fueling up on plants and probiotics to help your skin function (and look) its best.