One of the more common questions I get is, “Can perfume go bad?” The answer to that is yes. The corollary to that question is one of the more pervasive myths as I often will get the follow-up, “How long will my perfume last?” The answer to that is not as simple but in >95% of perfume on the market if you store it properly the answer is for a very long time. Perfume is not like milk and does not spoil after a set amount of time no matter what.
It is the first question which leads to the inaccurate assumption of the second. You can find a bottle of perfume which smells bad, or off, but it probably has nothing to do with time and much more to do with how it was handled. There are three enemies of perfume in the bottle; temperature, light, and oxygen.
If a perfume is stored at elevated temperature it will cause many of the more volatile components, usually the top notes, to evaporate. This leaves the less volatile notes behind and that completely changes the smell. This can happen very quickly if you keep the perfume above 90F/32C as things like aldehydes will be gone very quickly. Store your perfume below 65F/18F and this doesn’t happen very quickly. A perfume stored at this temperature will still have much of what you enjoyed when you first bought it.
Light, particularly sunlight, is the real enemy of perfume. Sunlight is ultraviolet radiation and many of the molecules used in perfumery can react with UV radiation and chemically change to something less pleasant to smell. If you store your perfume on a windowsill which gets direct sunlight this process can happen pretty fast. Keep your perfume out of the sunlight and it really doesn’t happen at all. Regular fluorescent light doesn’t have the same effect as sunlight and while I would still recommend keeping your perfume out of the light entirely it is the sun that does the most damage.
The first two things can easily be controlled by anyone just storing their perfume properly. The last thing which will have an effect is oxygen. The presence of oxygen happens as you use your perfume. The more you use it the more of that empty space in the bottle contains oxygen from the air. Now where temperature and sunlight can damage a perfume fairly rapidly oxygen does it much slower. One reason is the air in the bottle is only interacting with the surface of the liquid in the bottle. That is a very small surface for things to be happening. Compare that to light or temperature which interact with all of the liquid in the bottle. If there is any slight truth to the idea of an expiration date it is probably that the more you use a fragrance the more you keep adding oxygen and allowing for it to slowly interact with the perfume. Let me stress again this is a very slow process, we are talking years not months.
The answer to the question “Does perfume have a definitive expiration date?” is “No!” Any perfume you will have for a very long time will eventually change. That is a process which will take many years before it is apparent. So don’t feel like you need to use your favorite perfume up before it spoils that is just a myth.