1. What is the shelf life of sunscreen?
Will you buy more sunscreen and hoard it? Can I still use the sunscreen I bought last year? Last year, beauty bloggers circulated that it is best not to use sunscreen, because the sunscreen effect will be greatly reduced and may cause allergies. Is it true that all the money we hoard is "wasted"
Recently, Wang Baoxi, chief physician of Plastic Surgery Hospital of China Academy of Medical Sciences, said in the live broadcast of popular science consultation on the client of "People's Good Doctor" that unopened sunscreen can still be used normally within the validity period as long as it is well sealed and properly preserved. "The sunscreen that has been used, in another year, the matrix inside may have changed, and it is not recommended to continue using it."
Wang Baoxi explained that the physical protective components in sunscreen, such as zinc oxide and titanium dioxide, will not deteriorate and fail for a long time. However, other ingredients in sunscreen may deteriorate due to high temperature or exposure to air, resulting in serious bacterial growth and deterioration.
You can pay attention to the preservation method and expiration date marked on the sunscreen package. Generally, it should be kept in a cool and dry place, and the bottle cap should be tightened after each use. "Some sunscreens will print a picture of the bottle opening on the package, and write the words 12M or 6M at the bottom of the picture, indicating that the shelf life after opening is 12 months or 6 months."
Wang Baoxi stressed that when the texture and state of sunscreen are found to be different from those when it was first used, you should stop using it and buy a new sunscreen to avoid allergic or inflammatory problems caused by deteriorated sunscreen.
2. Precautions for using sunscreen
The use time of sunscreen
Don't use it before makeup, and don't apply sunscreen before going out. Sunscreen, like ordinary skin care products, takes a certain time to be absorbed by the skin, so sunscreen should be applied 10~20 minutes before going out and 30 minutes before going to the beach.
Enough use.
Sunscreen is not effective when applied, but only when it reaches a certain amount. Usually, when the amount of sunscreen applied to the skin is 2 mg per square centimeter, the due sunscreen effect can be achieved. It should be noted that SPF values cannot be accumulated. Two layers of SPF 10 sunscreen will only have one layer of SPF 10.
Don't mix different brands of sunscreen.
Mixed use will increase the possibility of skin allergy. Different brands of sunscreen have different ingredients. If they are mixed and overlapped on the skin, it may lead to mutual interference or repulsion of components, reduce the sunscreen effect and even cause skin allergies.
Don't use deteriorated sunscreen cosmetics.
If exposed to high temperature or direct sunlight for a long time, the effect of sunscreen may be reduced. Don't use deteriorated sunscreen cosmetics, because it not only reduces the sunscreen effect, but also irritates the skin more easily.
Pay attention to the dead angle of sun protection
When applying ordinary sunscreen products, you will generally pay attention to avoiding the skin around the eyes and lips like ordinary skin care products. Therefore, the skin around the eyes and lips once became a "sun protection angle." Eye cream and lipstick with sunscreen value are necessary. Don't worry that these things will put pressure on the fragile and sensitive special parts of the skin, because it is at least less stressful than exposure to the sun and ordinary sunscreen products. But in the choice, it is best to choose the physical sunscreen type.