Yes, an opened bottle degrades faster than a sealed one, mainly because each time it’s opened, a small amount of air, and with it oxygen and light, gets in, gradually triggering oxidation that changes the fragrance’s character over months and years, whereas a sealed bottle is fully protected until first use.

What actually happens once air gets in

Oxidation is the main culprit behind perfume ageing once opened; oxygen reacts slowly with certain aromatic compounds, particularly citrus and some floral notes, which is why a fragrance heavy in bergamot or fresh top notes often shows its age faster than a rich amber or oud-based scent. Each spray also introduces a tiny amount of extra headspace, air, into the bottle, and every time the cap comes off, however briefly, a little more oxygen and light exposure adds up over the bottle’s lifetime.

This doesn’t mean an opened bottle turns bad quickly, most perfumes remain perfectly wearable for one to three years after opening with reasonable care, but the process covered in our related answer on how quickly oxidation actually changes perfume is genuinely continuous from the first spray onward. Good storage habits slow it considerably. Our how to store perfume guide has the full detail, and the complete guide to perfume covers the basics of fragrance chemistry. Simple habits like recapping promptly and avoiding unnecessary exposure to air can meaningfully slow this process even in a bottle you use regularly.