The microbiome and barrier repair, minus the marketing

What are the skin barrier and the skin microbiome?

The skin barrier is the outer layer of skin, flattened cells held together by a mortar of ceramides, cholesterol and fatty acids, and the microbiome is the community of microbes living on top of it. That community of bacteria, fungi and mites has been mapped in detail by the sequencing studies described in a 2018 review of the human skin microbiome. The two interact. Strip the barrier with harsh cleansers and the microbial community shifts too: a study of skin surface pH found that soaps and even tap water raise skin pH, and an alkaline surface loosens the resident bacteria. That is part of why over-washed skin becomes reactive.

Which ingredients have good evidence for the skin barrier?

Ceramides, cholesterol and fatty acids in a moisturiser have good evidence, because they are the materials the barrier is made of. Glycerin, which has been doing this job for decades. Petrolatum for serious dryness. Beta-glucan has reasonable early data as a soothing, hydrating ingredient, mostly the laboratory and small studies gathered in a review of beta-glucan and skin health, which is a fair description and a long way short of the marketing. Niacinamide is well tolerated, and in a study of nicotinamide and barrier lipids it increased ceramide production in skin cells and cut water loss from dry skin when applied topically.

Are probiotics in skincare worth paying for?

Live probiotics in a cream are largely a marketing device, since a preserved cosmetic is designed to prevent bacteria growing in it. A 2026 review of probiotic skincare found that most products on sale rely on non-living microbial ingredients rather than live organisms. Postbiotics, meaning the by-products rather than the organisms, are more plausible and still thin on human data: a 2024 review found 14 published trials using well-characterised strains, all in volunteers with healthy skin. No cosmetic has been shown to durably reshape your skin microbiome, and nobody yet knows what an ideal one looks like.

What is the cheapest way to calm a stressed skin barrier?

The cheapest way to calm a stressed skin barrier is subtraction: use fewer products, not more. A stressed barrier is very often self-inflicted: two acids, a retinoid, a vitamin C and a scrub, on skin that never gets a night off. The NHS notes that skin inflamed by contact is most often caused by everyday irritants rather than allergies. Take things away for a few weeks and a lot of irritated skin settles without buying anything, as our piece on the skin barrier explains. That is unglamorous advice from a company that could be selling you a barrier serum, which is rather the point. If you want a routine that stays short, a MyAgenix read builds one around the basics.

General information about skin, not medical advice. MyAgenix offers cosmetic guidance to help you choose products. It does not diagnose or treat any condition. For anything that needs treating, see a pharmacist, your GP or a dermatologist.