4Brand dynamics -> Skincare knowledge

Just after the Double 11 Festival, many little sisters bought a house of skin care products, such as VC essence, Tranexamic acid essence, fruit acid skin essence, night cream, some of which are from other families. Then, many friends nervously asked me, can skincare products be used during the day? It is said that the skin will turn black during the day, and the face will be rotten... Do I need to hide essence from light? I want to brush my mobile phone for a while before I go to sleep after I use it up

It can be seen that many friends know that some skincare products have photosensitivity, but which specific ingredients in skincare products need to be protected from light? Why should we avoid light

This question seems to have been confusing everyone for a century, and Xiao Ruo feels it is necessary to give everyone a century's answer

Today we will discuss the issue of using this skincare product to avoid light

Firstly, what light should we avoid

The answer, sunlight, to put it correctly, is the ultraviolet rays in sunlight


From this table, it can be seen that (artificial) lamps in daily life contain relatively low levels of ultraviolet radiation, and their effects on the skin can be ignored. Therefore, there is no longer the burden of turning off the screen after applying skincare products.

Secondly, why should we avoid light?

The reasons why skincare products need to be used away from light vary, but there are mainly two points - the ingredients in skincare products will undergo photosensitive reactions; The Active ingredient in skin care products are easily oxidized and decomposed when exposed to light

1. Photosensitive reaction

Photosensitive reaction refers to some components that, when exposed to sunlight, absorb energy of corresponding wavelengths. During the process of releasing energy, it can damage human tissues, leading to symptoms such as itching, erythema, edema, and in severe cases, it may also cause blisters

The photosensitive reaction induced by external factors can be further divided into Phototoxicity reaction and photoallergic reaction according to the pathogenesis

The following summarizes the characteristics and differences of two different reactions:


For example, retinol (Retinol), or Tretinoin (which is prescribed by doctors, and should not be misused), and derivatives of retinol (retinol aldehyde, Retinal, and Retinol ester) are strongly recommended to avoid light after use

Although retinol itself does not have photosensitivity, its stability is poor, and it can be exposed to heat, water, ultraviolet radiation, or even air Peroxide reactions can cause it to lose its biological activity


Retinol will be converted into tretinoin on the skin and then into Tretinoin, which is photosensitive

Therefore, it is recommended to use ingredients containing vitamin A at night to avoid unnecessary skin problems. This is also one of the reasons why many multidimensional A alcohol products are night creams

2. Photodecomposition

Among the skincare ingredients that require avoiding light, these are the most common. They do not produce photosensitive reactions, but they are easily oxidized and decomposed when exposed to sunlight, greatly reducing their efficacy

Among these components, the most representative is vitamin C. Avoiding light is for better performance


Vitamin C inhibits the production of melanin by inhibiting key enzymes involved in skin melanin synthesis. On the other hand, vitamin C also has antioxidant effects. However, vitamin C has poor stability and is easily decomposed in environments such as high temperature, sunlight, water solubility, and non acidity

Many friends mistakenly believe that vitamin C has photosensitivity, so they dare not use products containing vitamin C during the day. Actually, vitamin C has no photosensitivity! It can be used during the day. It just has poor stability It is easy to oxidize under sunlight and cannot achieve optimal results

Thirdly, does fruit acid need to be protected from light?

If you have had a skin change with fruit acid or used products with high concentrations of acids, it is necessary to thoroughly implement the principle of "avoiding light" (or sunlight, mobile phones are fine)

Why? Because both fruit acid and salicylic acid have certain exfoliating functions, whitening and anti-aging functions are naturally available, but they will also cause temporary damage to the skin's own barrier function for a period of time - no break, no stand. In this case, it is important to strengthen sun protection or simply use it as a night cream

Fourth, can Tranexamic acid be used during the day?

First answer: Tranexamic acid can be used during the day. Sure, sure, and sure

Tranexamic acid is a protease inhibitor, which can inhibit the catalytic effect of protease on peptide bond hydrolysis, thus preventing the activity of enzymes such as inflammatory protease, and further inhibiting the disorder of epidermal cell function in the black spot

And inhibit the melanin enhancing factor group, and completely cut off the pathway of melanin formation caused by ultraviolet radiation. This means that black spots no longer thicken, expand, or increase, effectively preventing and improving skin pigmentation


Tranexamic acid essence is a whitening ingredient, but it is not photosensitive, so it is no problem to use it in the daytime

It should be noted that without sunscreen, there is no whitening, let alone skincare. Therefore, if you want to use Tranexamic acid essence to whiten, you'd better take care of sunscreen after using Tranexamic acid essence


Regarding the question of whether to avoid light after using the product, Xiao Ruo has temporarily thought of these, which are vitamin A, vitamin C, citric acid, and salicylic acid. The reasons for avoiding light vary, but they are all protected from sunlight, not mobile phones or lighting

That's all for today's topic. There are other questions that need to be understood. Welcome to leave a message for Xiaoruo in the message area. Xiaoruo will do everything in her power to answer everyone's questions

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