For years, the relationship between hydration and skin health has been hotly debated.
Can drinking more water meaningfully affect the skin, or is it simply a wellness myth? Research now offers a clearer, though nuanced answer.
We know that hydration supports every cell in the body, including the cells responsible for maintaining the skin’s structure, barrier function and nutrient environment. But the relationship isn’t as simple as “drink more water, get hydrated skin.”
Studies show that increasing total body water can produce improvements in skin hydration and elasticity — mainly in people who weren’t well hydrated to begin with (Palma et al., 2015). So while oral hydration isn’t a topical treatment for glowy, plump skin, it does influence the internal conditions that allow skin to function optimally and maintain adequate hydration.
Let's dive into the science.
Hydration and Skin Function
Body hydration begins at the cellular level.
In adults, total body water makes up roughly 50–60% of body weight and underpins essential physiological processes such as circulation, thermoregulation and nutrient transport. When systemic hydration declines, cellular efficiency (including that of skin cells) and metabolic efficiency can be impaired.
Within the skin, the dermis acts as the body’s major water reservoir.
In-vivo Raman spectroscopy studies estimate dermal water content at around 70–74% in healthy adults, providing elasticity, turgor and nutrient diffusion. Maintaining this reservoir depends not only on fluid intake but also on electrolytes, which play a key role in regulating fluid balance and water distribution across tissues and cells.
The Skin Barrier and Water Retention
Even if water reaches the skin, it must remain there. The skin barrier (often described with the “brick and mortar” analogy) has the dual task of keeping irritants out and keeping vital water in.
The barrier relies on:
- Corneocytes (the “bricks”)
- Lipids like ceramides, cholesterol and fatty acids (the “mortar”)
- Natural humectants inside skin cells that hold onto water
Water can still escape from the surface through transepidermal water loss (TEWL), a normal physiological process. When the barrier is disrupted, TEWL increases, and the skin becomes more prone to dehydration and sensitivity.
It's important to note that water doesn’t sit freely at the skin’s surface; only “free water” evaporates. The rest is bound water, held in place by structural components including collagen, elastin and hyaluronic acid.
Most water storage occurs in the dermis. These molecules give the skin its ability to bind and retain moisture internally.
What Role Do Electrolytes Play?
Electrolytes such as sodium, potassium, chloride and magnesium help regulate fluid movement between the spaces inside and outside cells. Through the sodium–potassium ATPase pump (powered by ATP) these minerals maintain the gradients necessary for nerve signalling, muscle contraction and water transport.
When electrolyte balance is disrupted through heat, exercise, travel, stress or drinking large amounts of plain water without minerals, the body may struggle to retain water effectively.
In rare cases, excessive intake of plain water can dilute sodium levels (hyponatremia), leading to fatigue, confusion or dizziness.
Electrolytes don’t directly increase skin hydration, but they support systemic water balance so hydration can reach and remain in the tissues that depend on it, including the skin.
How Collagen Supports Hydration
Collagen, particularly Type I collagen, creates the structural network that holds water within the dermis. With age, collagen production decreases, and existing fibres can weaken, reducing the skin’s capacity to retain moisture.
Hydrolysed collagen peptides supply amino acids like glycine and proline, used by fibroblasts to produce new collagen. Clinical trials and meta-analyses show small but measurable improvements in dermal hydration, elasticity and density after 8–12 weeks of consistent intake, depending on dose and formulation quality.
Vitamin C supports this process by acting as a cofactor for enzymes that stabilise collagen’s triple-helix structure.
Together, these components form the architectural basis that allows hydrated cells to function optimally.
How Does Drinking More Water Improve Skin Hydration?
The idea seems intuitive: if your skin feels dry, drink more water. The latest research suggests a more nuanced reality.
The most recent studies show:
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Individuals with low fluid intake may see improvements in deep skin hydration when increasing water consumption (Palma et al., 2015; Akdeniz et al., 2018).
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Those already drinking adequate water see minimal or no visible changes at the skin surface (Palma et al., 2015; Akdeniz et al., 2018).
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One study found that topical moisturisers had a far greater impact on skin hydration than increasing water intake (Seol et al., 2024).
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A systematic review showed that increased water intake mainly improves hydration in the deeper skin layers, not necessarily the upper layers where dryness is felt and seen (Akdeniz et al., 2018).
So, unless you are systemically dehydrated, drinking extra water is unlikely to noticeably change surface skin hydration.
Skin dehydration is largely a barrier function issue, not a systemic hydration issue — and while drinking enough water supports overall health, it's not an easy shortcut to dewy or moisturised skin.
Daily Hydration Rituals
So, how can you support the conditions that allow the skin to stay hydrated, both from within and at the surface?
These foundational habits strengthen internal fluid balance, structural integrity and the skin barrier — all of which contribute to healthier, more resilient skin.
1. Rehydrate intelligently
Hydration isn’t just about drinking more water; it’s about replenishing what the body actually loses through modern, busy life. During exercise, heat exposure, long travel days or periods of increased sweating, the body loses both water and essential minerals like sodium and potassium. Rehydrating with electrolyte-containing fluids helps restore this balance, so water can move efficiently through cells and tissues. Consistent electrolyte balance keeps systemic hydration stable, which supports the dermal water reservoir that skin relies on.
2. Support skin structure
The skin’s ability to retain water is closely tied to the health of its structural proteins. Marine collagen peptides supply amino acids that fibroblasts use to produce collagen and extracellular matrix components, while vitamin C acts as a cofactor that helps stabilise collagen’s triple-helix structure. Over time, this combination supports the architecture that binds water within the dermis. The stronger the structure, the better the skin can hold and distribute moisture.
3. Protect the surface
Even if internal hydration is optimal, the skin can still lose water rapidly through transepidermal water loss (TEWL). A well-functioning barrier acts as the skin’s protective seal, locking in moisture and preventing evaporation. Gentle cleansing, consistent moisturising and avoiding over-exfoliation help keep this barrier intact. When the barrier is resilient, internal hydration lasts longer — allowing the deeper layers to remain nourished while the surface stays soft, supple and balanced.
4. Create hydration-supportive habits
Small, daily behaviours are one of the best ways to influence hydration that lasts. Eating water-rich foods (like fruit and vegetables), managing stress, maintaining regular sleep habits, reducing caffeine or alcohol intake and avoiding prolonged indoor heating or very hot showers all help regulate fluid balance and minimise unnecessary moisture loss.
It's the simple habits that reinforce your internal and external hydration systems, helping the skin function at its best.
References:
Palma L, Marques LT, Bujan J, Rodrigues LM. Dietary water affects human skin hydration and biomechanics. Clin Cosmet Investig Dermatol. 2015;8:413–420. https://doi.org/10.2147/CCID.S59912
Verdier-Sévrain S, Bonté F. Skin hydration: A review on its molecular mechanisms. J Cosmet Dermatol. 2007;6(2):75–82. https://doi.org/10.1111/j.1473-2165.2007.00300.x
Proksch E, Brandner JM, Jensen JM. The skin: An indispensable barrier. Exp Dermatol. 2008;17(12):1063–1072. https://doi.org/10.1111/j.1600-0625.2008.00786.x
Akdeniz M, Gabriel S, Lichterfeld A, Blume-Peytavi U, Kottner J. Does dietary fluid intake affect skin hydration in healthy adults? A systematic literature review. Clin Exp Dermatol. 2018;43(3):305–312. https://doi.org/10.1111/ced.13330
Seol JE, Choi SY, Park EJ, Kim KH, Youn SW. Effect of daily water intake and use of moisturiser on skin barrier function in healthy women. Ann Dermatol. 2024;36(1):1–8. https://doi.org/10.5021/ad.23.067
Hara-Chikuma M, Verkman AS. Roles of aquaporin-3 in the epidermis. J Invest Dermatol. 2008;128(9):2145–2151. https://doi.org/10.1038/jid.2008.61