Last summer’s sunscreen has not been used up, see the shelf life is still far away, then use it. In fact, in order to ensure a good sunscreen effect, it is best to use up the sunscreen after opening.
Sunscreens have a shelf life of two years or three years, but not within the shelf life, you can safely apply it to sunbathe. Dr. Yan Yan, from the Department of Dermatology, Peking Union Medical College Hospital, said that when cosmetics such as sunscreens are in contact with air, changes in temperature and humidity in the air can easily change their composition.
Although the sunscreen products in the next year may not have any side effects on the skin, the sunscreens with reduced effect may not achieve the desired sunscreen effect, and it is easy to make the skin red, black and even injured under direct sunlight. . It is best to use up the sunscreen within one year after opening. If you feel that it is a pity to throw away the sunscreen every other year, it can be applied to the hands and feet, and there will still be some sun protection.
Many people think that applying sunscreen is all right, Dr. Yan said, in fact, sunscreen should reach a certain thickness to have an effect, specifically about 2 milligrams per square centimeter. And sunscreen should be used 15 minutes to half an hour before going out, and should be applied once every 2 hours, in order to achieve the best sunscreen effect.
Another thing to note is that you should apply a moisturizing cream before applying sunscreen. Try not to contact the skin directly. This will not only add some moisture to the skin, but also reduce the irritation to the skin.