Sunscreen is essential for protecting your skin from harmful UV rays during sun exposure. Yet, many people are tempted to reuse a tube that lingered from the previous year. According to experts, this is a mistake—always opt for a fresh tube instead.
As vacation packing begins, you might spot that sunscreen tube from last year and wonder: Can I still use it? Reusing it seems practical—saving product and reducing waste. However, Christine Lafforgue, president of the French Society of Cosmetology, warns against it, as reported by the Metro daily.
Sunscreens contain specialized molecules that absorb ultraviolet wavelengths (UV rays), which can lead to skin cancers like melanoma. UVB rays primarily cause sunburns, while UVA rays accelerate premature skin aging.
Sunscreen forms a protective film on the skin. Its UV-absorbing molecules feature conjugated double bonds—alternating strong double and single bonds between atoms that can degrade over time.
Regulations allow 28 UV filters in sunscreens: 26 organic filters that absorb UV rays and 2 mineral ones that reflect them. The formula also includes water, oils, preservatives, and sometimes alcohol, creating a stable emulsion.
No sunscreen is designed for reuse the following year, notes Christine Lafforgue. Heat exposure and repeated tube openings accelerate degradation, compromising protection. At the end of your holidays, discard any remaining sunscreen to ensure reliable defense against the sun.
