Even with cosmetics you bought thinking, "This seems promising...", are you truly experiencing their effects? Many people use them based on vague feelings like, "It seems to be getting better," or "It must be good because it was expensive." And as you know, the skin that uses these cosmetics is constantly renewing itself through turnover. This means it's important to have a solid grasp of how we perceive cosmetic effects and of skin turnover itself.

Q. Where do we experience the effects of cosmetics?

There are three types of effects. First, there are the effects felt immediately after use, such as "skin feels firmer" or "skin looks brighter." Then, there are effects that emerge after continuous use for a week or a month, like "improved firmness" or "less noticeable dark spots." Finally, there are psychological effects. I believe these three points are key to cosmetic efficacy. Therefore, if you approach cosmetics with doubt, thinking, "I wonder if it really works...", their effectiveness will be diminished. If you lose even one of these three points, you can no longer fully utilize the cosmetic, and if you use it with anxiety or doubt, its sustained effects will also weaken. This is because factors like the sympathetic nervous system have a subtle influence.

The common "Please try for one week" offers are made because manufacturers want you to experience the effects through continued use. The companies formulate their products so that results can be seen within a week. This is because about half of the stratum corneum is replaced every week. With such changes, even slightly rough areas will become smooth.

Q. How does skin turnover relate to the effects of cosmetics?

While a 28-day cycle for skin turnover is now the established theory, it can actually take anywhere from 25 to over 50 days. It varies significantly with age. However, most people feel that their skin has largely renewed itself within about a month. I often suggest, "Please use one bottle completely to see the true effects of the cosmetic," because manufacturers design their products to be used up in about one to two months. After about a month of continuous use, you can see how the cosmetic has worked on the newly regenerated skin. You can then experience a certain degree of change in your skin from using the cosmetic, which I think is a key point for observing its effects.


Q. Does the speed of turnover also differ depending on skin thickness, such as around the eyes or on the cheeks?

Yes. Thinner areas of skin turn over faster, and areas that don't move much turn over slower. This can also vary greatly from person to person, so it's hard to generalize. Incidentally, the turnover around the eyes is actually slower than commonly believed. Although the skin there is thought to be thin, it's not actually that thin. Therefore, it takes a considerable amount of time to experience truly lasting effects from eye creams, for example.


Q. In terms of skin turnover, at what stage do skin troubles and dullness occur?

Healthy skin turnover typically follows a 28-day cycle, but it takes time for the stratum corneum to fully mature after being generated. However, when the skin is in a state of irritation or has had too much of its stratum corneum removed, it accelerates turnover to compensate. Faster turnover, conversely, means immature keratinocytes reach the surface. Immature keratinocytes cannot withstand dryness, making the skin prone to irritation. Therefore, people with chronic skin irritation often have constantly accelerated turnover, which paradoxically leads to a poor skin condition. They also become more susceptible to rashes because their skin cannot defend itself properly. Those with chronically rough skin need to be protected from above, essentially "capped," until properly matured keratinocytes reach the surface.


Q. When you say "cap," do you mean something like a cream or serum?

Something that firmly protects the skin's surface, like a cream, is most important. If a cream doesn't suit you, then something like a petrolatum ointment – purely oil. The effects of cosmetics on the skin are primarily seen when turnover is occurring in a healthy state. When turnover is disrupted, you cannot discern the true effects of the cosmetic until it is normalized.

I thought skin irritation was due to sluggish turnover.

That's mostly incorrect. Some manufacturers have products designed to accelerate turnover by removing keratinocytes, and it seems this misconception has spread since their introduction. Of course, there are methods like chemical peels and exfoliation, but if not managed properly, they can lead to a persistent state of irritation.

Q. What kind of management are you referring to?

In short, if you're going to influence turnover, you must provide adequate protection afterward. It's problematic to simply remove and then offer no follow-up. Currently, manufacturers are not adequately educating people about the correct understanding of peeling and keratinocyte removal. I always emphasize, "Do not remove too much stratum corneum." Avoid over-exfoliating with facial cleansers; instead, be careful not to let loosely attached keratinocytes peel off and protect your skin.

Q. Is aging related to skin turnover?

Faster turnover isn't necessarily better; a cycle of 50 days or 25 days can be fine. What matters is a suitable speed for the individual. While aging does affect turnover, innate constitution seems to have a greater influence than age. Turnover is essentially the metabolism from when skin cells are generated until they shed. Some people have a faster basal metabolism, while others have a slower one, and as long as their skin is healthy, that's fine. It's like having slow and fast eaters; some are deliberate, and others are in a rush.

Q. Do the nutrients in cosmetics also affect their efficacy?

Some cosmetic ingredients penetrate the skin and act on cells. These would correspond to the "nutrients" you mention. Their effects have been verified. However, unlike pharmaceuticals, their effects are not as rapid or dynamic. This is because the Pharmaceutical Affairs Law restricts the amount of such ingredients that can be included. That's precisely why we encourage continuous use of cosmetics. Even if the effects aren't immediately visible, there's a good chance they are working within a cycle of about a month.

Q. If I use a product for a long time, will I sometimes stop feeling its effects?

There are two reasons for this. One is that the initial sense of novelty has faded. Alternatively, if you initially experienced effects but then notice roughness developing with continued use, it likely means the product and your skincare system weren't compatible.


Cosmetics are not medicine. Therefore, the extent to which advertised ingredients influence immediate versus sustained effects is probably not as significant as claimed. What's more important is the user experience, the texture... in essence, the most crucial elements are those that aren't particularly exciting to highlight. They're like a secret ingredient in cooking. To emphasize new products, manufacturers tout new formulations or technologies, but when consumers are distracted by these aspects, they often fail to discern the true quality. Rather than judging immediately whether it works, it's best to apply it consistently and observe after a few days: is my skin responding well? Is it maintaining a good condition?

Miyoji Okabe Official Website
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