TL;DR
- Ceramides make up approximately 50% of stratum corneum lipids by mass and are the primary structural component of the skin barrier
- When ceramides are depleted, transepidermal water loss rises, skin becomes dry and reactive, and actives may cause more irritation than intended
- Oestrogen has positive effects on barrier function over time — but decreased sebum and changing skin physiology can leave some individuals experiencing more dryness and sensitivity during early HRT
- Ceramide-containing moisturisers are among the most evidence-based approaches to supporting barrier repair and restoring stratum corneum lipid composition
- Formulation matters as much as ingredient listing — ceramide on a label does not guarantee meaningful barrier repair
The skin’s outermost layer — the stratum corneum — is not just dead cells stacked on top of each other. It is a precisely organised structure: corneocytes (the “bricks”) surrounded by an intercellular lipid matrix (the “mortar”). Ceramides are the dominant component of that mortar, comprising approximately 50% of stratum corneum lipids by mass, alongside cholesterol and free fatty acids.
This lipid matrix is what gives the skin barrier its two critical functions: keeping water in and keeping irritants, pathogens, and allergens out. When it is intact, the skin is resilient. When it is depleted, transepidermal water loss (TEWL) rises, the skin becomes dry and reactive, and substances that should remain at the surface may cause more irritation than they would on a healthy barrier.
What depletes ceramides
Several common skincare practices and conditions deplete ceramides or transiently impair the barrier:
Surfactants in cleansers — particularly sodium lauryl sulphate — can transiently disrupt barrier lipids and increase TEWL, particularly with repeated exposure. Retinoids increase cell turnover and can transiently impair barrier function during initial use. AHAs and BHAs accelerate corneocyte turnover and, particularly when overused, may transiently impair barrier function. Low humidity environments increase TEWL. UV exposure damages barrier lipids and contributes to photoageing. Conditions including atopic dermatitis and xerosis are characterised by significant ceramide deficiency — ceramide depletion is central to the pathophysiology of atopic dermatitis and directly underlies the chronic barrier dysfunction seen in the condition.
Oestrogen and barrier function
One of the less-discussed effects of oestrogen is its positive influence on skin barrier function. In transfeminine patients specifically, oestrogen has been directly documented to promote epidermal thickness, alongside its other well-known feminising effects on skin. Separately, in cisgender postmenopausal women, research has found that the stratum corneum’s ceramide profile becomes depleted and shifts toward shorter-chain species after menopause — changes that are not seen in women taking HRT, and that correlate with serum oestradiol levels. That dataset comes from a different population than transfeminine patients on HRT, but the direction of the effect — which is more consistent with oestrogen preserving or supporting normal ceramide homeostasis than with promoting ceramide depletion — is consistent with what’s observed directly in trans women. Taken together, feminising HRT does not appear to be a net barrier stressor over time, based on currently available evidence; in many respects, it supports barrier integrity.
However, during the early period of HRT, as sebum production decreases and the skin adapts to a new hormonal environment, some individuals experience increased dryness and sensitivity. This is a practical clinical observation rather than a well-established mechanistic finding — but it is common enough to be worth anticipating. Barrier-supportive skincare is particularly useful during this period, not because the barrier is objectively compromised by HRT, but because reduced sebum and changing skin physiology can make it feel more reactive than usual.
For this reason, introducing potent actives such as retinoids gradually is often better tolerated during early HRT than starting at full strength. This is consistent with general dermatological advice for anyone new to retinoids — early HRT is simply a context in which caution is especially warranted.
What to look for in a ceramide product
Formulations should ideally contain multiple ceramide types. Commonly used ceramide species in barrier-repair formulations include ceramide NP (also referred to as ceramide 3), ceramide AP (ceramide 6-II), and ceramide EOP. The stratum corneum has an approximate physiological lipid composition of ceramides, cholesterol, and free fatty acids — and formulations approximating these physiological lipid ratios have shown favourable barrier-repair properties in experimental and clinical studies, though many effective products do not perfectly reproduce this ratio.
Formulation chemistry determines delivery at least as much as the ingredient list. A ceramide appearing on a label does not guarantee meaningful barrier support — lamellar emulsions and biomimetic delivery systems designed to mimic the organisation of the stratum corneum have shown favourable barrier-repair properties in experimental studies. This is why two products with identical ceramide ingredients can perform very differently.
A note on nomenclature: ceramide naming varies between regulatory regions. Ceramide NP, ceramide 3, and N-(tetracosanoyl)-phytosphingosine refer to the same compound. Reading ingredient lists requires knowing both the INCI name and the common name.
⚠️ Clinical note: The ceramide biology described here is well-established. The HRT-specific observations — increased dryness and sensitivity during early transition — are clinically recognised but not extensively characterised in controlled studies. The epidermal-thickness effect of oestrogen is documented directly in transfeminine patients; the ceramide-profile data on menopause and HRT comes from cisgender postmenopausal women and is presented here as a parallel, not direct evidence in trans women. The physiological lipid ratio data derives from formulation science and experimental barrier repair literature; effective clinical products span a range of compositions.
Sources
- Feingold KR. Thematic review series: Skin lipids. The role of epidermal lipids in cutaneous permeability barrier homeostasis. J Lipid Res. 2007;48(12):2531–2546.
- Sakai T. Stratum Corneum Ceramide Abnormalities in Atopic Dermatitis: Pathophysiology and Implications for Disease Management. J Dermatol. 2026;53(3):380–387.
- Yeung H, Kahn B, Ly BC, Tangpricha V. Dermatologic Conditions in Transgender Populations. Endocrinol Metab Clin North Am. 2019;48(2):429–440.
- Kendall AC, Pilkington SM, Wray JR, Newton VL, Griffiths CEM, Bell M, Watson REB, Nicolaou A. Menopause induces changes to the stratum corneum ceramide profile, which are prevented by hormone replacement therapy. Sci Rep. 2022;12(1). DOI: 10.1038/s41598-022-26095-0.
- Distribution and Cosmetic Ingredient Review. Safety Assessment of Ceramides as Used in Cosmetics. Final Report — ceramide INCI nomenclature (Ceramide NP, AP, EOP).
