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 side 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. For the sunscreen that has been used, after another year, the matrix inside may have changed, so it is not recommended to continue using it.

Physical protective components in sunscreen, such as zinc oxide and titanium dioxide, will not deteriorate and fail because of long time. However, other ingredients in sunscreen may deteriorate due to high temperature or exposure to air, resulting in serious bacterial growth and deterioration.

Duration of sunscreen:

Consumers can pay attention to the storage method and expiration date indicated 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 an open bottle 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.

When you find that the texture and state of sunscreen are different from those when you first use it, you should stop using it and buy a new sunscreen to avoid allergic or inflammatory problems caused by deteriorated sunscreen.

Refer to the above? People's Daily Online-Can sunscreen be used after one year's storage?