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Does Hair Bleach Expire (or Go Bad) After Mixing or Opening?

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While hair dye today puts a whole rainbow of color at your disposal, however, there’s no denying that bleach blonde hair is and long has been the perennial favorite. 

Gentlemen Prefer Blondes, after all (just ask Marilyn Monroe), and there’s no shortage of bleach-blonde boy bands (just ask NSYNC-era Justin Timberlake).

A whole host of Hollywood starlets and pop idols have done the bleaching deed, including Madonna, Lady Gaga, Jennifer Lawrence, Gwen Stefani, Katy Perry, Emma Stone, Jennifer Hudson, and Emilia Clarke.

We have Jean Harlow (and the media circus surrounding her) to thank for the term “Blonde Bombshell”; wouldn’t you know? She bleached her hair, too.

Still, your attempts at transforming yourself, Blonde Bombshell will blow up in your face if you use expired bleach — or will it?

How Long Does Hair Bleach Last? Can You Use Bleach Beyond Its Expiration Date?

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Does hair bleach expire? Hair bleach expires quickly after opening the package. In some cases, hair bleach can expire in as little as 20 minutes.

However, it’s critical that you read the product packaging carefully – if the product contains bleach powder, hair developer, or other common chemicals and ingredients the expiration date will vary.

Due to the various formulations that often include bleach powder and liquid developer, determining how long a hair bleach mixture lasts is by far the trickiest question to answer.

There are lots of competing claims out there, including that hair bleach powder can last for up to a year after you’ve mixed it. However, as demonstrated below, there are variations to this, and it can go bad sooner.

Even that isn’t the full story.

While the peroxide may be ready to be mixed in for a year after you first start using it, the actual bleach you’ve just introduced into the mixture will spoil extremely quickly, as soon as 20 minutes after mixing.

As such, if you’re going to mix up hair bleach, you’d better know what you’re doing and where you plan on applying it before getting started so you can add it before the bleach starts to go south. If bleach (or sodium hypochlorite) is an active ingredient, our recommendation is to use this type of product immediately.

Why does bleach start to go bad? As with all manner of other hair products, it has to do with oxidation.

Once this process begins, not only will the hair bleach start to degrade, but it will start to become dangerous to use. So, we don’t recommend using bleach beyond its expiry date or any expired hair product.

By contrast, box hair dye can last up to three years in optimal conditions. That’s a long time. In order to achieve the best results, we recommend storing hair products in a cool, dry place. Also, avoid direct sunlight.

On the other hand, hair dye gone bad can also dye your hair a Grinch-y greenish color, to say nothing of the rancid odor that can accompany it if it’s degraded.

Hair Dying vs. Bleaching (Liquid and Powder Form)

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Before we go much further, it’s worth drawing a distinction between hair dye and bleach in particular. After all, both are used to change your hair color, so can we consider them as one thing here?

Well, the answer here is yes and no.

For practical purposes, box dye and a bottle of bleach have similar properties in terms of longevity and spoilage, which is why you’ll see some overlap in our discussion of how long they last, why they go bad, and what you can do to preserve them.

At the same time, however, there are some differences between bleach and hair dye that are worth noting.

For one thing, bleach and hair dye work in different ways. While both change the appearance of your hair, bleach does this by stripping away your natural hair color, whereas hair dye essentially “paints” over it.

As a result, while both can change your appearance, bleaching your hair can be seen as a bigger step since it’s permanent, whereas different hair dyes last for different periods of time but aren’t quite as much of a long-term commitment.

On the other hand, there’s a reason why “Bleach Blonde” is a hair and fashion identity unto itself, but we never hear about a “Bleach Redhead” or “Bleach Brunette.”

While bleaching can dramatically lighten your hair color by stripping away your natural color in favor of bleached platinum blonde, that’s the only coloring effect it can accomplish. By contrast, hair dye allows you to change your hair to a variety of different colors.

The Pros and Cons of Peroxide

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Hydrogen peroxide is often at the center of the hair bleach dilemma. On the one hand, this allows hair bleach to be so incredibly effective in lightening your hair by stripping away the natural color, giving you a look unlike any other.

Google around, and you’ll see arguments that hair bleach can outlast other hair care products, and peroxide is often at the center of that claim.

However, that’s not quite accurate. For one thing, as with any chemical compound, peroxide can indeed go bad; as with other hair care products, once you open the bottle, the clock starts ticking.

In fact, from the time that you open the bottle, it can expire in as soon as six months, which is faster than many bottles of shampoo, conditioner, and hair dye.

While it may expire a lot faster than you might think, you don’t even have to wait for hair bleach to expire to suffer negative effects.

For example, while hydrogen peroxide can be used as a disinfectant, too much of a good thing can backfire. As such, an excess of peroxide in bleach can irritate your skin and damage the hair shaft. This can be especially prevalent in your scalp around your hairline.

One way to prevent this is to use something that can help take the edge off. Clean cotton and petroleum jelly are just two of the common options offered to help ease the hydrogen peroxide.

In addition, you’ll want to try to keep the peroxide in your hair for as short a time as possible, since the longer you leave it in there, the greater the chance you could accidentally irritate or even burn your scalp. This is an important step, so follow the directions closely.

And that’s not all: that hair-lightening power also comes at the potential cost of weakening your hair’s cuticles. For those not in the know, your cuticle is the outer layer of your hair and is essential for protecting and strengthening it.

The hydrogen peroxide in bleach can prove problematic here because, to bleach and dye your hair, it needs to enter the cuticle, which in turn can cause damage such as split ends, frizzing, and even breakage.

That breakage is especially concerning since this, combined with the chemical reaction between peroxide and the elements during oxidation, can lead to hair loss if left unchecked and done to excess.

Incidentally, deep conditioner treatments can help with this, so if you’re going to invest in hair bleach, you should probably look into a few conditioners as well.

When applied properly, hair bleach can produce some of the most stunning hairstyles imaginable.

However, if you don’t know what you’re doing and how to counteract these potential negative effects, you could find yourself feeling burned, literally.

Bacterial infections are another potential consequence of peroxide and hair bleach gone bad.

That being said, when used properly, hair bleach can be incredibly effective in a way that hair dyes often can’t be and can even alter your hair color one to four levels.

Hydrating Your Hair

Cute white women with naturally curly dark hair wearing a brown sweater and blue jeans.

One of the best ways to take advantage of the best qualities of hair bleach while preventing its worst consequences is making sure that your hair and scalp are well-hydrated. Among the best things to pair with hair bleach to hydrate your scalp and hair are:

  1. Olive oil: Olive oil, though this is, as with hair bleach itself, a case where a little goes a long way. You should only need a few drops applied with your fingertips while focusing on the ends of your hair for maximum effect.
  2. Coconut oil: Coconut oil can do wonders for sealing your hair and preventing protein loss, which can cause your hair to degrade further. Try rubbing it in your palms to warm it up a bit before applying it to frizzy spots as well as ends.
  3. Argan oil: Argan oil has a ton of antioxidants and can help protect your hair from free radicals and further damage caused by not protecting it before the bleaching process (learn more).
  4. Almond oil: Almond oil can add some much-needed vitamin E and proteins, both of which can help strengthen your hair and prevent the breakage that can otherwise accompany bleaching (learn more).

In addition, you’ll want to take care to protect your scalp from the sun, especially right after you have applied the bleach solution.

The combination of the light and heat from sunlight with fresh bleach can cause some nasty irritation and burning on your scalp. Make sure that you’re using an SPF spray that is specifically formulated to protect your hair as well as your scalp when outside. Keeping your hair and scalp in good condition is critical when using a bleach solution.

In Conclusion

Hair bleach kits (like Manic Panic and other drugstore brands) are definitely the trickiest hair products when it comes to the maintenance and balancing act that is essential for good hair care.

Get something wrong, and you could severely damage your hair, hurt your scalp, and have to live with the consequences for weeks or even months to come.

If you have reason to believe that your bleach has passed its expiration date, the best way to avoid problems is to throw it away.

Sometimes the product’s container will include an expiration date, so it’s always a good idea to check the product’s packaging for an expiration date. It’s also one of the easiest ways to determine if the product’s still useable.

However, if you can get it right, are sure to protect and hydrate your scalp, and don’t use any expired bleach or other products, the Blonde Bombshell look can truly blow people away. 

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