1. Opened expired products cannot be used.
If the sunscreen after opening has expired, it is best not to use it again.
The sunscreen ingredients contained in the expired sunscreen have been greatly oxidized by the air, and the sunscreen effect has been greatly weakened or even completely disappeared. After use, the sunscreen effect cannot be achieved, making the skin easy to get sunburned; Moreover, if it is a sunscreen packed in a plastic bottle, the bottle itself will degrade, and the particles contained in the plastic will be integrated into the sunscreen, which is not good for the skin and is easy to cause symptoms such as allergies and dermatitis.
2, unopened can be painted on the body.
If it is an unopened sunscreen that has not expired for a long time, it can be used to wipe the body, because the skin on the body is much thinner than the skin on the face, and it is not as sensitive as the skin on the face. It is ok to use it in moderation.
3. How long is the shelf life of sunscreen?
Generally speaking, the shelf life marked on the sunscreen package is 3 to 5 years, or even 8 years, but this is unopened. The shelf life of the sunscreen after opening is generally only about half a year to one year, so if the sunscreen is opened, it is best to use it up within one year.
4. Can I apply the expired products to my body?
You can apply it.
If the sunscreen has not expired for a long time, there is still a lot left. If you are reluctant to throw it away, you may wish to apply it to your hands, arms, or other places with thick skin, which can play a certain isolation role and will not hurt your skin, but be careful not to apply too much.
5. The principle of sunscreen
Physical sun protection: Physical sun protection protects the skin by blocking ultraviolet rays. Specifically, the anti-particles in sunscreen form a protective layer on the skin surface, reflecting the light waves that may cause harm to the skin in ultraviolet rays, thus protecting the skin from harm, and the anti-particles themselves will not be absorbed by the skin.
Chemical sunscreen: Chemical sunscreen protects the skin by absorbing ultraviolet rays. Specifically, before the skin is damaged by ultraviolet rays, chemical atoms first absorb substances that may cause harm to the skin in ultraviolet rays, thus achieving the purpose of sun protection.