How to Know if Hair Dye Is Expired

• Check the expiration date on the hair dye package to see if it's expired. Keep in mind that some products might not list a "best by" date, though.
• Throw out dyes that are opened for longer than a year. If you've never opened the dye, it's okay to hold onto for up to 2-3 years.
• A strange smell, product separation, and overly bright color are all signs that your hair dye is expired.
• Rinse out your hair dye right away if it burns or irritates your scalp.

How can you tell if hair dye is expired?

Inspect the package for an expiration date. Some hair dyes come with a “best by” or “use before” date, which helps you know if your dye is expired. Check the side of the package—if you find an expired date, toss out the product. A lot of beauty companies don’t include a freshness date on their products, so this might not be a feasible option.

Best Practices

Toss out pre-opened dyes after a year. Opened dye doesn’t go bad right away—instead, it will last about 1 year before expiring. If you opened your dye more than a year ago or can’t quite remember when you first used it, throw out the product to be safe. If you can’t remember when you purchased or opened the dye, consider getting new hair dye altogether.

Hold onto unopened dye for 2-3 years. If you’ve had your dye for longer, toss it out and pick up a new product from your local beauty shop.

Toss out dyes that were stored in a sunny, hot area. Peroxide and ammonia are common chemicals found in most hair dyes. Unfortunately, both of these chemicals create an unpleasant chemical reaction when they’re exposed to high heat. Examine your storage area—if it’s consistently over 75 °F (24 °C), toss out the dye and pick up something new. This chemical reaction causes the dye to separate, which isn’t good.

Throw out the dye if it's leaking. Hold the bottle and tip it upside-down to ensure there are no leaks. If the bottle is leaky, you can assume that the dye has gone bad, and throw it out.

Inspect the packaging for dents, damage, wet spots, or fading. Dents, moisture, and other outer damage can spell bad news for hair dye. If your hair dye packaging looks damp or worse for wear, throw it out and use a new product. Sometimes, dye bottles will look lumpy or swollen because of bad chemical reactions.

What does expired hair dye look and smell like?

It has a strange or foul odor. Does the dye smell very metallic, or just rotten overall? If so, you can assume the dye is expired.

Study the dye color to see if it resembles the correct color. The dye should look like its respective shade, and not look like a completely different shade.

It’s separated into a milky fluid. Open up the dye and see if the dye is smooth, or it’s already separated. If you see the telltale milky liquid, get rid of the dye. Dyes don’t have to be in a cracked, leaky container to separate. Your dye bottle might be completely intact, but the product could still be separated.

A mixed batch is bright- or light-colored. After it's mixed, a proper dye will look a bit lighter than the desired shade. If the color is already a deep shade, you can assume that it’s expired.

Side Effects of Expired Dye

Rinse out dye immediately if it burns when you apply. Hair dye should never hurt when you apply it to your hair. If your scalp burns after you apply the dye, rinse out the product and throw out any of the old dye.

Check for an abnormal tint in your recently-dyed hair. When a dye expires, the product loses its original quality. Because of this, your hair may tint in an undesired shade. Examine your hair after you’ve dyed it—if the dye is tinted green or some other unwanted shade, you can assume that the dye is expired. For example, some brown hair dyes are made with red pigment. If the dye is expired, your hair might look red instead of brown.

Watch for hair color that fades quickly after application. Check the dye label to see how long the color is supposed to last. If the color is fading really quickly, there’s a good chance that the dye you used was expired. For instance, if your dye should last a month but fades after 2 weeks, the dye was probably past its prime. Sometimes, expired dye simply won’t work, leaving your hair the same color it originally was.

Feel your hair to see if it’s coarse or frizzy after dyeing it. While it isn’t very common, expired hair dye can occasionally lead to frizzy and damaged hair. Check your hair after you’ve applied the dye—if it’s looking broken, then your old dye might have been expired.