What is the difference between physical and chemical sunscreens?

Physical and chemical sunscreens differ fundamentally in their mechanisms of action against ultraviolet (UV) radiation. Physical sunscreens, often containing zinc oxide or titanium dioxide, function by creating a physical barrier on the skin that reflects and scatters UV rays away from the skin. This means they provide immediate protection upon application, as they do not require time to absorb into the skin or interact with sunlight.

In contrast, chemical sunscreens contain organic compounds that absorb UV radiation. These ingredients work by converting UV rays into heat, which is then released from the skin. This process typically requires a short period after application to allow the sunscreen to bind to the skin and become effective.

Understanding this distinction is essential for making informed decisions about sun protection, as each type of sunscreen has its own advantages and considerations, such as potential skin sensitivity and the need for reapplication.