You’re getting ready for a big day and pull out that box of hair colour from the back of your bathroom cabinet. A thought crosses your mind: has this been sitting here too long? It’s a common question, and the answer is more important than you might think. Using hair colour isn’t like using an old spice that has just lost a bit of its potency; the consequences can affect both your hair’s health and the final look you were hoping to achieve.
Hair colour, whether it’s a box dye from the store or a professional formula, is a chemical product. Over time, these chemicals break down and change, which is why they do indeed have a shelf life. Paying attention to expiration dates and knowing the signs of a product past its prime can save you from a hair disaster.
How Long Does Hair Dye Typically Last?
An unopened box of permanent hair colour usually has a shelf life of about three years. However, once you mix the developer and the colourant together, the clock starts ticking much faster. The mixed formula is only good for that single use, typically about one hour. For products that are already pre-mixed in a bottle, like some semi-permanent or direct dyes, they generally last between one and two years if unopened and stored properly.
Spotting Hair Colour That’s Gone Bad
Your senses are your best tool for checking if your hair colour has expired. A significant change in the product’s smell is a major red flag; if it has a sharp, unusually strong, or off-putting chemical odour, it’s best to discard it. You should also look at the consistency. If the cream is separated, unusually runny, or has a strange texture, the emulsion has likely broken. Finally, trust the date. Always check the packaging for a Period After Opening (PAO) symbol—the icon of an open jar with a number and the letter “M” inside—which tells you how many months the product is good for after it’s been opened.
What Happens If You Use Expired Hair Dye?
Using hair colour that is past its expiration date is a gamble with disappointing and sometimes damaging results. The most common outcome is that the colour simply doesn’t work as intended. You might end up with a shade that is much lighter, darker, or more uneven than the box promised. In more severe cases, the compromised chemicals can cause irritation to your scalp and skin. At its worst, expired dye can lead to dry, brittle, and broken hair because the chemical process is no longer stable.
Tips for Storing Your Hair Colour Properly
To help your hair colour last as long as possible, proper storage is key. Always keep the boxes and bottles in a cool, dry place away from direct sunlight. Avoid storing them in humid areas like a bathroom cabinet that gets steamy from showers. Extreme temperatures, whether hot or cold, can also speed up the chemical degradation process, so a linen closet or a bedroom shelf is often a better choice.
While it might be tempting to use that old box of hair dye to save a trip to the store, it’s a risk that rarely pays off. For the sake of your hair’s health, colour accuracy, and overall condition, it’s always best to use fresh, in-date products. Your hair will thank you for it with vibrant, predictable, and beautiful results.