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Why Did My Blonde Hair Turn Brown? | 6 Culprits

Perhaps they do have more fun, but blonde hair can be challenging to maintain, especially for those that were born with the natural golden halo of blonde locks. Melanin is a chemical in every human that determines hair, skin, and eye color.

So, if you were born with blonde hair or had it chemically created and find yourself asking, “why did my blonde hair turn brown,” this is the guide for you. Read on to learn more.

Why Your Blonde Hair Turned Brown

There are several reasons blonde hair goes dark, whether it’s your God-given color or it came from quality bleach. Let’s take a look at the most natural reasons before jumping into the things we do regularly that can affect the buttery brightness to fade.

1. Pigment Genes Activated

Science can be complex. However, our genes play a massive role in our appearance, thanks to how much melanin is in our bodies. In addition, there are two primary types of melanin found in all humans. A surplus in one or the other will determine specific characteristics.


It contains sulfur and determines yellows and reds. It colors human lips, while a large amount also provides freckles. With a surplus of pheomelanin, you will more than likely have red hues and lighter features.


It is from the oxidation of the amino acid tyrosine. It is usually the most abundant of melanin, which provides black and browns in hair, skin, and eye colors. Eumelanin allows the skin to tan while providing a richer color to eyelashes and brows.

2. Blame Your Hormones

As hormones change several times throughout your life, melanin properties can activate and deactivate. This phenomenon can cause color changes in your life. For example, if lower levels of eumelanin suddenly activate, then blonde hair can begin to grow darker without warning.

Eumelanin becomes more potent as you age. This can happen from the point of toddlers with bright blonde hair growing darker with puberty, as well as post-menopausal women’s hair losing luster before turning grey or white.

3. Unkind Water

Water can be the culprit to why your blonde mane is turning brown. Hard water can cause deposits packed with minerals that can tint the hair darker.

Copper and chlorine can be just as contaminating to blonde hair. Hard water can come from the source or the build-up in the pipes. Either way, it’s like a slow dye on light locks.

Read Next: How to Boil Hard Water to Wash Your Hair

4. Build-Up

Blonde hair is the most absorbent when it comes to pollution and product build-up. Unfortunately, this causes the blonde strands to darken with a hue that can be unattractive.

Removing the build-up can restore your golden locks, but you need to realize what is causing that build-up in the first place. Products like gel, mousse, and hairspray all cause gunk that can weigh down the hair even if you try to wash it out.

Air pollutants are another cause of build-up, so if you live in a smoggy area or are in a smoke environment, this, too, can cause your hair to darken.

5. Burnt Hair

Burnt hair has an unforgettable smell. When hair gets singed, it can turn black and charred. However, think of drying your hair and then using a flat iron or curling iron like a piece of bread in the oven. First, it will dry out. Then, it will turn golden brown.

If you leave it in the oven, it will char to burnt dust. When you dry blonde hair and use heat products, you can cook the hair to a golden brown over a period of time. The buttery blonde will eventually turn darker.

6. Too Much Purple Shampoo

Purple shampoo is a miracle product that can bring blonde hair back to life. It has the gentle power of brightening up brassy locks without causing damage.

However, using purple shampoo too often can cause a different reaction. The whiter the hair turns from using purple shampoo will allow it to absorb the pigment of purple into the cuticle, resulting in darker hair.

Prevent Blonde From Turning Brown

For a guide to why did my blonde hair turn brown, a woman using purple shampoo on her blonde hair in the shower


Human hair has several functions, including how we feel about ourselves. So, now that we know what causes blonde hair to turn brown, let’s look at how to reverse the process or, better yet, possibly prevent it.

Cut the Brass

Every blonde knows brassy hair. Unfortunately, it happens to the best of us. Brass comes from air pollution, swimming, chemicals in hair products, build-up, colored shampoos, or the water you use to wash your hair.

Cutting the brass is easy when using good products. For example, using a blue or purple conditioner weekly will keep the brass at bay. Plus, applying good, moisturizing conditioners can help prevent brassiness from affecting your strands. 

Use a Shower Filter

Hard water and mineral deposits are one of the biggest culprits in blonde hair turning brown. Adding a water filter to the house can reduce the minerals from dying your lovely locks.

If a whole-house water system isn’t in the budget, a shower head filter can suffice the need to filter out excess chlorine and minerals that can build up and weigh down your hair.

Remove the Build-Up

Since the build-up of products and chlorine can cause blonde hair to darken, using a clarifying or chelating shampoo once a week can strip the build-up from each strand. The chelating shampoo is more potent than clarifying shampoo, but be careful when using either.

These shampoos are stripping agents that can be extremely drying. When in doubt about the proper process, you can schedule a clarifying treatment with your local salon.

Read Next: How to Clarify Your Hair at Home

Limit Heat 

Since you now know that heat can cause darkening hues to your hair, among all the other damages that direct heat can trigger, limiting the use of heat on your hair can prevent dark shades. When using heat tools, be sure to use a quality heat protectant on your hair beforehand.

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Turn to Chemicals

If you have done all these remedies and preventions yet still have darker hair, then it’s best to chalk it up to your changing hormones and melanin. However, adding in highlights, toners, or blonde dyes to brighten your blonde can be just the right touch to restore your blonde bombshell presence once again.

Frequently Asked Questions

Blonde woman with brown eyebrows smiling at the camera with her shoulders exposed

Elena Zhogol/Shutterstock

Here are a few related questions when talking about why blonde hair turns brown.

Why do some natural blondes have dark eyebrows?

Due to a natural increase in eumelanin, natural blondes will darken over time. Eyebrows will darken much quicker and sooner than the hair on your head.

Just because someone has darker eyebrows doesn’t mean they don’t have natural blonde locks. Plus, as people age, their eyebrows thin. Eumelanin makes this process less noticeable. 

What is the rarest natural hair color?

Red hair is the rarest color on the planet. Less than 2% of the population has natural red hair. Pheomelanin is the rarer type of melanin, which causes red pigments in hair follicles.

Red is one of the most difficult pigments to get rid of when it’s natural. However, it is the most challenging pigment to maintain when chemically created. 

Why does blonde hair turn green when dying it brown?

The lack of moisture and nutrients in bleached hair can cause the brown dye to tint green. The best way to prevent this is to use a high-quality, nourishing hair dye or have a professional change your color.

If the hair does turn green, using ketchup or vinegar to neutralize the chemical reaction will remove the green tint.

So, Why Did My Blonde Hair Turn Brown?

As you now know, blonde hair can turn brown for a number of reasons. Whether it’s hormonal or a build-up of products and overheating, there are several fixes to restore your lovely locks.

So, when your hair, captures a darker hue, see which options in this guide suit you best. Pst… want to know a secret? You can easily find out by taking our “what color hair should I get” quiz. Trust us — it’ll open a world of hair color options you never knew existed.