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What Happens if You Leave Toner on Hair for Too Long?

Toners are hair treatments used to enhance dyed or bleached hair color by removing undertones.

However, they must be used appropriately to achieve the desired results. You will not achieve your desired hair color if you leave the toner on your hair for too long.

What Will Happen if I Leave the Toner on My Hair for Too Long?

Leaving toner on your hair for too long results in overtoning. Over toning compromises the hair color and does not achieve the desired result. It also damages the hair, resulting in breakage and split ends. Over toned, the hair looks dull and feels rough.

Other side effects of leaving the toner on your hair for too long include losing your hair’s natural curl pattern such that the hair does not bounce back or feels like a straw. The hair may also feel frizzy and brittle. It does not hold color.

How to Prevent Over-Toning Your Hair

Below are tips to prevent over toning your hair:

Choose the Right Toner

How to Prevent Over-Toning Your Hair - Choose Right Toner

Avoid using extremely powerful toners such as hydrogen-peroxide and ammonia-based toners if your hair has mild undertones.

A blue or purple shampoo followed by the respective toning conditioner may be all you need.

Be particularly careful with ammonia-based toners. Although they are quite effective, they make your hair prone to damage.

They cause your hair to be brittle, limp, and dull.

On the other hand, hydrogen-peroxide toners cause permanent changes in hair color.

They can also cause permanent damage to the hair that can only be resolved by cutting your hair.

Observe the Appropriate Pre-Application Steps

First, ensure that your hair is clean and damp. If you apply the toner immediately after bleaching, you do not have to worry about this, as the hair should already be clean and wet.

If you are toning several days after bleaching, dampen the hair before applying the toner. Shampooing the hair just before toning is not recommended.

If using an ammonia-based or hydrogen-peroxide-based toner, ensure to correctly mix it with the developer to ensure it is efficient and avoid damaging your hair.

Leave the Toner on the Hair for Only the Recommended Time

How to Prevent Over-Toning Your Hair

The appropriate amount of time to leave the toner on the hair depends on the extent of undertones, the health condition of the hair, the type of toner used, and hair time.

On average, it ranges between 2 and 45 minutes. Semi-permanent toners take 2-15 minutes to process, demi-permanent toners take 5-20 minutes, while permanent toners take 30-45 minutes.

Always check the manufacturer’s instructions on the toner packaging regarding how long to leave the toner on the hair. Conducting a strand test to take the guesswork of the toning process is recommended.

To do a strand test:

  1. Separate a small section of the hair
  2. Apply the toner and leave it for the recommended time
  3. Within this time, carefully monitor how the color development is progressing
  4. Take note of how long the hair takes to achieve its desired color
  5. Clean the hair. If it is still brassy, you will have to leave the toner on the rest of the hair for longer. If it is grayish, it is over-toned, and you should shorten the processing time.

Wash and Condition Hair Properly

How to Prevent Over-Toning Your Hair - condition hair

If you do not wash your hair properly after toning, there will be residual toner on the hair resulting in undesirable hair color, damaged hair, dry scalp, or an allergic reaction.

The residual toner could also react with other hair products you use, further damaging the hair.

Therefore, wash out the toner thoroughly after processing it. Rinse the hair with lukewarm water.

Do not use hot water, as it will damage the hair follicles. On the other hand, cold water will close the cuticles before the toner has been washed out. This may result in an itchy scalp and dandruff.

Then wash with a toning shampoo or a moisturizing shampoo to nourish the hair if there are mild undertones remaining.

Use a sulfate-free shampoo that is recommended for dyed hair. Then rinse off the conditioner.

You may finish with a leave-in conditioner to further nourish the hair and make it shiny and smooth.

Don’t Tone Your Hair Too Frequently

Aside from leaving the toner on the hair for too long, over-toning can also be caused by applying toner too frequently.

Recommended For You:

How Long Should I Leave Toner on Bleached Hair?

How Long To Leave Toner On Your Yellow Hair?


While you may think that leaving the toner on your hair for longer than the recommended time yields better results, conversely, it damages the hair and causes the hair strands to be oversaturated with color pigment.

Therefore, you want to adhere to the stipulated processing time, monitor color development closely, and wash the hair properly to avoid further processing. You should observe aftercare practices to preserve hair color and promote healthy hair.

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James Hunter

James Hunter is a talented stylist from LA with a wealth of experience. After training at the nVisually Hair Salon & Academy, he's spent over a decade as a senior stylist, always ready to share his styling tips and tricks. James has a knack for trying out new things and often brings this adventurous spirit to his work at Hairdo Hairstyle.