In daily life, most people confuse hydration with moisturising. In skin care, they usually think that as long as they do one of them, the skin can be moisturised. However, this is actually one of the biggest cognitive misunderstandings in the field of skin care. From the perspective of dermatology, hydration and moisturising are two completely different concepts. Their mechanism of action, skin level and effect are all essentially different. Misunderstanding these two concepts often leads to skin care behaviour to double the effort and may even cause irreversible damage to the skin barrier.
1. Definitions: Two Completely Different Skin Care Mechanisms
To figure out the problem that is misunderstood by 90% of people, we need to first disassemble these two core words from the definition and understand which link they affect the skin respectively.
1.1 What is Hydration? Increase Skin Moisture by External Force
Hydration, literally understood, refers to the direct replenishment of water to the skin through external channels. This process mainly acts on the cuticle of the skin. Under normal conditions, our cuticle will contain a certain amount of moisture (usually 10%-30%) to maintain the softness and smoothness of the skin.
When you feel that your skin is dry and tight, using products with high water content such as toner, essence, mask or spray can briefly infiltrate the cuticle layer, so that the keratin cells can temporarily absorb water and expand. This process is simply rehydration. It is characterised by immediateness and temporary, which can quickly relieve the tightness after cleansing or in a dry environment, but this feeling of moisture is often only an appearance and will not last long.
1.2 What is Moisturising? Reduce the Rate of Water Loss
Unlike hydration, the core of moisturising is locking rather than replenishment. Moisturising refers to helping the skin maintain existing moisture through specific means and reducing or preventing water evaporation through the epidermis. This process is medically called “reducing water loss through the epidermal”.
The moisturising ability of the skin fundamentally depends on the health of the skin barrier. This barrier is mainly composed of sebaceous membrane, keratinocytes and intercellular lipids, which together form a dense physical protective wall to prevent excessive evaporation of water in the body and resist the invasion of external stimuli. Therefore, the essence of moisturising is to maintain and repair the barrier function of the skin.
1.3 Core Logical Differences
Simply put, the logical relationship between the two is as follows:
Hydration is to increase the moisture content on the surface of the skin.
Moisturising is to maintain the moisture content on the surface of the skin and prevent it from running away.
To describe it in a rigourous physical term, rehydration is to increase income, and moisturising is to reduce expenditure. Only when the income is greater than the expenditure can the water content of the skin rise steadily.
2. Misconception: Why Is It Wrong To Only Hydriate without Moisturising?
After understanding the definition, we can understand why many people feel that they have used a lot of hydration products, but their skin is getting drier and drier. This is not an illusion, but because it has fallen into a vicious circle.
2.1 The Evaporation Trap of Moisture
The main component of many hydration products is water. If after using such products, products with water-locking functions such as lotions or creams are not used in time, the moisture replenished to the surface of the skin will evaporate quickly in the air.
Especially in autumn and winter or dry areas, the air humidity itself is low, and the evaporation effect will be more obvious. What’s worse, in the process of evaporation, the water will also take away the skin’s own moisture that is not much through vaporisation heat. You may feel the more replenish, the drier it is.
2.2 Ignoring the Invisible Damage of the Skin Barrier
Simply relying on hydration and neglecting moisturising means that the skin barrier function is not paid attention to or repaired. If the skin barrier has been damaged (for example, intercellular lipid loss), the skin’s water-locking ability will be naturally insufficient. At this time, no matter how much water is replenished, it is like pouring water into a cup with a hole, which can never be filled. Repeated hydration will only keep the skin keratinous cells in an unstable state of hydration for a long time. On the contrary, it may loosen the barrier structure due to excessive hydration, further aggravating water loss.
2.2 Misleading of Physiological Feedback
When the skin feels dry, the sebaceous glands will try to secrete more oil to try to lock in moisture, which is the so-called oily outside and dry inside phenomenon. If you only pay attention to hydration and ignore moisturising at this time, the dry nature of the skin will not be solved, and oil secretion may be more vigourous, which will lead to clogged pores, causing acne, making the skin condition more complicated.
3. Scientific Skin Care: How to Work Together to Give Full Play to The Best Effect
Since hydration and moisturising are two different things, the correct skin care strategy should be “rehydration first, then moisturising”. The two work together to maintain the stable water content of the skin cuticle.
3.1 Seize the Golden Time of Skin Care
In order to maximise the effect, it is recommended to carry out skin care immediately within 3 minutes after cleansing. At this time, the cuticle of the skin is in a state of hydration, the pores are open, and there is still moisture on the surface, which is a good time to apply subsequent products. If the skin is completely dry before the care is carried out, the effect will be greatly reduced.
3.2 Accurately Distinguish Product Functions
When choosing a product, you can judge its main focus according to the texture and formula of the product without sticking to the specific ingredient noun.
Products that focus on hydration: usually with a clear texture, such as toner and essence. Their function is to quickly infiltrate the cuticle and replenish moisture to the skin.
Moisturising products: usually rich in texture, such as lotions and creams. Their function is to form a protective film on the surface of the skin to physically prevent moisture evaporation and provide repair support for the lipids under the cuticle.
3.3 Pay Attention to the Change of the Skin Itself
In addition to external care, the state of the skin itself is also very important. The moisturising ability of the skin depends on a healthy cuticle. Excessive cleaning and frequent exforation will destroy the sebaceous membrane on the surface of the skin, resulting in a decrease in the ability to lock water. Therefore, maintaining the health of the skin barrier is itself the best moisturising means.
3.4 Adjust the Strategy According to the Skin Quality
Different skin types should have different emphasis on hydration and moisturising.
Dry skin: the water content of the cuticle is low, and the sebum secretion is insufficient. This kind of skin not only needs a lot of hydration, but also needs to provide sufficient moisturising support to simulate and strengthen the function of the sebaceous membrane.
Oily skin: Although the secretion of epidermal oil is vigourous, the water content of the cuticle often does not meet the standard. This kind of skin needs moisturising products with a refreshing texture that will not clog pores. At the same time, it still needs to be moderately moisturised to correct the compensatory secretion of oil caused by lack of water.
FAQ
Q: Why is my skin still dry after drinking a lot of water every day?
There is no direct causal relationship between the two. The moisture of the human body is primarily supplied to the core organs, and finally reaches the skin. The water content of the skin is mainly controlled by the barrier function, not the water content of the whole body. If the barrier is damaged, no matter how much water you drink, it will evaporate and lose. To relieve dryness, it is necessary to rely on external “locking water”. Drinking a large amount of water has little effect, and excessive drinking may also increase the burden on the kidneys.
Q: Can frequent use of moisturising products keep the skin moist?
No, and it may be counterproductive. The instant moisture of the spray is temporary. If it is allowed to dry naturally, the moisture will also take away the original moisture of the cuticle when it evaporates, resulting in the skin to be drier. Correct practice: stay for one minute after spraying, absorb excess water with a cotton pad, and then immediately apply lotion or cream to lock in the moisture.
Q: The more frequently you apply the mask, the better the moisturising effect will be?
No, excessive mask application is harmful. The mask is forced to replenish water through the sealing effect, but applying it every day or for too long (more than 15-20 minutes) will cause excessive hydration of the cuticle, swelling and loose cells, destroying the barrier function, and making the skin more fragile and sensitive. It is recommended to wash and apply moisturising products 2-3 times a week.