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What Happens If You Leave Hair Dye In Too Long?

What Happens If You Leave Hair Dye In Too Long?

Dying your hair does bring a new change to your appearance. Almost everyone wants to dye their hair at least once in their lifetime. You can dye your hair at the salon or at home.

If you are dyeing your hair at home, you must know that the ingredients in the hair dye can damage your hair if not used properly.  

When you leave hair dye for too long, it can damage your hair. Along with weakening the hair, it can absorb the moisture in your hair, making it dry. All these factors can lead to hair loss as well. 

This article will explain why you must not leave hair dye longer than instructed and the time limit for each type of dye. We will also take you through a few tips on preventing the color from fading. 

What Happens When Hair Dye Is Left on Too Long?

A hair dye contains various ingredients that can affect your hair when not used according to the instructions. Leaving the hair dye for too long can cause the hair dye to absorb all the moisture in your hair follicles. When the moisture is absorbed, your hair will feel brittle and dry. 

Usually, 30 minutes is adequate for the chemicals in your hair dye to develop and permeate your hair.   

hair bleach

Can Leaving Hair Dye on Too Long Cause Hair Loss?

What is important to understand is that a hair dye will not slow down or stop your hair growth. It can lead to hair loss.

Hair coloring requires heavy combing and rubbing, which accelerates hair loss. When you leave the hair dye for too long, the chemicals can cause damage to your hair, and due to heavy combing, there will be more hair loss. 

When you leave the hair dye longer than recommended, your hair shaft can become physically weak. If you use a hair dye to lighten your hair from its natural color and leave it for too long, a lot of damage can happen to your hair, leading to hair loss.

Hair dyes used for lightening hair contain high levels of peroxide. Lightening hair dyes contain peroxide to remove eumelanin pigments from your hair shaft and replace them with blonde colors.  

Even when you are not lightening your hair, you must not leave it for too long as it can cause hair loss.  

How Long Can Dye Stay on Your Hair?

Ideally, most hair dyes should be left for at least 30 minutes. You must not let the dye stay on your hair for longer than 45 minutes. 

Let us understand the process here:

When you apply hair dye, it needs 20 to 30 minutes for the ammonia, peroxide, and the other ingredients to come into effect and work on your hair cuticles. During this time, the natural pigmentation of your hair changes. 

The dye fully develops and permeates your hair in the last 15 minutes. If you rinse your hair earlier than 20 to 30 minutes, you will not be able to see any change, and there will be uneven color coverage throughout your hair. 

You should not exceed 45 minutes because you will damage your hair. Hair damage will lead to hair loss and dryness. 

Hair Dye

Does Hair Dye Get Darker the Longer You Leave It On?

Whether your hair will get darker when you leave the hair dye for longer depends on the dye you use. 

If you use a permanent hair dye and leave it for a long time, your hair will not get darker. Most permanent dyes develop during a specific time, and after that, they stop. 

Leaving it for more time will not darken or lighten your hair. Your hair will dry out and damage when you leave permanent hair dye longer than the manufacturer’s instructions. Permanent dyes contain chemicals that can cause damage when left for a long time.  

If you use temporary hair dye and leave it for longer, it will darken your hair. Temporary hair dyes deposit color on the most superficial layers of your hair.

In other words, they deposit on the surface level, which means they deposit color on your hair cuticles. They need lesser time to develop because they only deposit and activate pigments. 

Hence, leaving temporary dye for a long time can darken your hair as the dye will continue depositing pigments. 

Another point you must remember is that leaving black hair dye on your hair for long durations will not make any difference. It will only damage and dry out your hair. 

Should I Shampoo after Hair Dye?

After dyeing your hair, you must wait for a total of 72 hours (three days) before shampooing your hair. This is because it takes three days for your hair cuticle layer to close completely.

The closing will trap the color molecules. When you wait three days, the hair dye or color will last longer.  

Tips To Follow For Shampooing Your Hair After Hair Dye

Here are a few tips related to shampooing after coloring your hair:

  • Remember to always condition your hair. Conditioning will prevent your hair from drying. 
  • Sodium laureth sulfate is a very common ingredient used to make shampoos. It is a cleansing agent. It produces lather and can strip off natural oils along with your hair color. To prevent stripping of color, using sulfate-free shampoos and conditions will be helpful and will prevent fading. 
  • Remember to change your water temperature when you are shampooing or raising your hair with water. You must adjust it to a cold or lukewarm temperature. Rinsing your hair will hot water will lift the outer hair cuticle layer. This can cause fading of hair color. 
  • Avoid thick treatment hair masks. These masks will penetrate your hair and strip the color out of them. Skipping in-shower masks and treatments will prevent your hair color from fading out. 
  • You must remember that the chemicals in a hair dye will make your hair vulnerable to water. You must avoid washing your hair every day if you want your hair color to last for an extended period. Shampooing or washing your hair every day will lead to fading of color and natural oils from your hair. Washing your hair twice or thrice a week will be helpful. In case your hair gets oily, dirty, or greasy, you can use dry shampoos. 
  • Do not excessively rinse your hair when you shampoo. Once you shampoo and condition your hair, tilt your hair backward and let the water run over your hair several times. 
  • You must avoid swimming without a cap. Saltwater or chlorine will strip or alter your hair color once dyed. Dark hair can turn dull and lose its shine, whereas blonde hair can turn green due to chlorine.  

Tips To Follow For Styling Your Hair After Hair Dye

Always use a heat protectant before using hot hair styling tools. When you blow dry your hair and use a curling iron or any other tool without a heat protectant, the color of your hair will fade or change. Heat can strip off the color and hydration. 

When you use a heat protectant, you are reducing moisture loss from your hair. It will also help in smoothing and protecting your hair from humidity. Too much exposure to heat or humidity will lead to fading of color. 

You must also avoid excessive blow drying and styling products that have too much alcohol content in them. The chemicals or alcohol content can open up the cuticle leading to the color slipping out.

These tips will help your efforts while dyeing your hair not go down the drain. 

Timing for Different Types of Dye

There are different types of dyes available in the market. Each dye has its time requirements. If you leave any type of dye for more time, it can cause damage. 

Here is a guide for how long you must leave the hair dye in your hair.   

Type of Dye Time
Demi-permanent dyes At least 20 minutes
Semi-permanent dyes 15 to 30 minutes
Permanent dyes 30-45 minutes
Gradual hair dyes 30- 45 minutes
Henna 2-6 hours.

Leaving the hair dye for longer than the mentioned time can lead to hair damage and loss. Additionally, ensure that you read the instructions of the hair dye box carefully. 


If you leave hair dye in for too long, you will only damage your hair. Your hair will become physically weak and will start thinning. You must avoid leaving it for too long. Always read the instructions on the box and see the time they have mentioned. 

As mentioned before, each type of dye has different timings. You can always set up a timer or alarm once you have applied the hair dye. 

Though hair dyeing is a long process, the result will always make you happy. You can have fun with the colors and dye your hair in the color you like. What you must remember is to do it right to enjoy the results.