Depending on the fragrance, from six to 18 months, if stored correctly. Once a bottle of fragrance has been opened it should be used because all fragrance deteriorates with time: light, citrus-based perfumes in as little as six months; floral scents in about a year and a half. Indeed, Perfumes can go bad, but it does depend on the fragrance itself. Certain fragrances seem to be more fragile than others, hence will sour more easily

Expensive perfumes which are made from rare essential oils tend to last for a longer time than simple drug store scents. Also, most perfumes that you purchase in department stores contain only 33% pure perfume oil (vs. 60% in niche perfumes), and the rest is alcohol, water, butane and fillers. These “extras” can lend a hand in “turning” your perfume to the “Dark – Side” quicker.

If you notice a smell change, than it is starting to go bad. If the original potent smell has diminished than it has gone bad as well.  Watch out for color change. The color can turn darker and look much thicker. When you open a bottle of perfume that you haven’t used for a while, wipe the opening of the bottle   with alcohol. If it smells bad, then discard the content. If you notice a vinegar /acidic smell than the contents have changed. If it doesn’t smell like it once did, it’s bad too. Rancid perfumes seem to all have the same acrid odor over the original notes.