Wondering whether your shampoo has gone bad probably doesn’t feature high on your list of health concerns. As shampoo is frequently used on a daily basis, a bottle isn’t usually left open or unused long enough for this to be of any concern. But what if you find an old bottle of shampoo buried away in an old suitcase for instance? Will it still be safe to use? For this reason shampoo does have a shelf life, albeit a long one and some shampoos also have an expiry date.


If you take a look at your bottle of shampoo, you might notice a small symbol which looks like an open lid. Inside this symbol is a number, usually 12 or 24. This indicates how many months your shampoo is considered to be safe for use once it’s been opened. In the US, most bottles of shampoo won’t display an expiry date because these are not required on cosmetic products. However, you will find an expiry date on anti-dandruff shampoos because these are classified as an over-the-counter drug (OTC) which must display such information.

The reason we are able to store shampoo for such long periods of time, even after opening, is because of the preservatives they contain. Since one of the main ingredients of shampoo is water, as soon as a bottle is opened, it is immediately exposed to air and other contaminants making it susceptible to the growth of harmful microorganisms. Therefore, don’t be tempted to dilute your shampoo by adding water. This will render the preservatives less effective as well as introducing the possibility of contamination.

While the use of preservatives sometimes receives negative publicity, without them, the shelf life of the majority of cosmetic type products would be greatly reduced. Instead of storing our shampoo bottles in the bathroom, we’d have to refrigerate them to retain their freshness. But even so, their quality would begin deteriorating within a few days and start going off, much like milk or cheese for example.

Shampoos are preserved and bottled in such a way that enables them to withstand the variable storage conditions consumers are likely to subject them to. This could be shelf time standing under hot lights in a supermarket or the back of a boiling car boot after purchase as well as the days or weeks left open in a steamy bathroom.

Although preservatives greatly prolong the shelf life of shampoo, this doesn’t mean the quality won’t deteriorate eventually. If it has been stored for a long time, the liquid can separate, become discolored or start to smell strange. The length of time taken for this to happen varies depending on the shampoo but if this does occur, you should discard the contents. Although it’s unlikely to cause any negative effects, the fragrance or effectiveness of the product will have been compromised.

Most of the time you won’t have to worry whether or not your shampoo has gone off since they have such a long shelf life. However, anti-dandruff shampoos do have an expiry date, so if you’ve stored a bottle away for some time, always check the date before using it and if the liquid has separated or smells strange, the safest option is not to use it. As long as you use your shampoo within the time span indicated after opening and don’t add anything to it such as tap water, your shampoo should remain perfectly safe and usable.