Permanent Vs Semi-Permanent Hair Color: What You Need To Know
Written by Irina Webb
Hair dyes are a fantastic way to express yourself, experiment with your look, or even cover a few grays. Whether you’re lightening or darkening your locks, the variety of types of hair dyes on the market can feel overwhelming. From semi-permanent hair dye to permanent and demi-permanent options, it can be tricky to know where to start. Today, we’ll explore the differences between permanent and semi-permanent hair color, so you can choose the best hair color option for your needs.
Permanent Vs Semi-Permanent Hair Color
By the end of this article, you’ll have a clear understanding of the differences between permanent and semi-permanent hair color. You’ll learn about their ingredients, how they work, and how long they last. Whether you’re looking for subtle hair glosses, vibrant color changes, or effective gray coverage, this guide will help you make an informed decision.
What Is Permanent Hair Color?
To begin with, permanent hair color penetrates deeply into the hair shaft to alter natural hair color permanently. Hence, using a permanent hair color would bring about a dramatic transformation, whether you’re aiming for a bold new shade or simply trying to achieve complete gray coverage. Because it lasts longer than other types of hair dyes, it’s a popular option for those looking for durability and vibrancy.
Further, permanent color is also widely used for root touch-ups and lightening or darkening your hair. However, this type of dye requires a higher commitment because it doesn’t fade entirely over time—it needs to grow out or be recolored.
What Are The Ingredients In Permanent Hair Color?
Generally speaking, all permanent hair colors contain four main building block ingredients:
- a developer (removes the existing hair color);
- an alkaline agent (opens the hair cuticle to let the dye in);
- hair dyes; and
- inactive ingredients.
First, the developer removes the existing hair color. Typically, they use hydrogen peroxide for this function.
Second, the alkaline agent opens the hair cuticle to let the hair dye in. Normally, it is ammonia, but if the color is “ammonia-free,” it is usually ethanolamine. In rare cases, it is sodium perborate or sodium percarbonate.
Third, the hair dyes penetrate the hair and adhere to it. While there are over 100 hair dye substances, the most common ones are para-phenylenediamine (PPD), toluene-2,5-diamine sulfate (TDS), and resorcinol.
Finally, the “inactive” ingredients include surfactants, emulsifiers, hair conditioners, plant extracts and oils, fragrance, and silicones.
Is Permanent Hair Color Safe?
No, in my opinion, no permanent hair color is safe. Actually, the FDA instructs users to do a patch test before every use, even if you have used the same hair color for many years. Why is that? Because hair dye substances are potential sensitizers, meaning you can develop a reaction to a hair dye after several applications and even after several years. (Also, manufacturers can change hair dye ingredients without a warning.)
In fact, the Scientific Committee on Consumer Safety (SCCS) has assessed over 110 hair dye substances and classified them into extreme, strong, and moderate sensitizers. For instance, commonly used para-phenylenediamine (PPD) and toluene-2,5-diamine sulfate (TDS) are extreme sensitizers. As for resorcinol, although it is a moderate sensitizer, it has a link to endocrine disruption and thyroid suppression (source).
In addition, the alkaline agents, aka “hair shaft openers,” are highly corrosive, damage the hair, and may irritate the skin and lungs. Oftentimes, it is ammonia, and if the hair color is “ammonia-free,” it is usually ethanolamine. They are also associated with reproductive toxicity. You can learn more in my blog post Are Ammonia-Free Hair Color Brands Better?.
The good news is that in my Permanent Hair Color Rating List, which assesses more than 60 hair colors for safety, you can easily spot those that are free of PPD, TDS, or resorcinol. Also, you will be able to readily see which hair color is ammonia-free, which one is free of ethanolamine, and which one is free of both ammonia and ethanolamine. This will make your selection process much easier.
How Long Does Permanent Hair Color Last?
In general, once applied, permanent hair color stays until it grows out or you recolor it. On average, you’ll need a root touch-up every 4–6 weeks, especially if you’re covering gray hair.
Although permanent hair color doesn’t wash out like temporary or semi-permanent ones, it will fade and change shade over time. Some factors that can cause it to lose its intensity include:
- your hair condition
- washing frequency
- hair products
- shade (darker shades tend to last longer than lighter ones), and
- the types of hair dyes used.
To make permanent hair dye last longer, the hair-care market suggests you try:
- using color-safe hair products
- using a hair mask at least once a week
- avoiding shampooing for a couple of days after dyeing your hair.
Frankly, I don’t know if these steps really help or if they are just marketing claims.
What Is Semi-Permanent Hair Color?
Unlike permanent hair color, which strips your hair of its natural color, semi-permanent hair dye coats the surface of the hair shaft without penetrating it deeply. This makes it a less permanent option for those looking to experiment with new shades, enhance the tone of your hair, or achieve subtle hair glosses.
Next, unlike permanent dye, semi-permanent color doesn’t require a developer or an alkaline agent to open the hair shaft (again, typically ammonia or ethanolamine). This makes it a gentler choice for your hair. However, it’s not ideal for gray coverage as it doesn’t last as long or alter the hair’s structure significantly. Also know that permanent hair color covers gray hair more effectively than semi-permanent hair color, particularly if you are more than 50% gray.
There are different types of semi-permanent hair dye. First, there is traditional one that gradually fades over several washes. And second, there is demi-permanent hair dye, a hybrid option that lasts longer and contains a mild developer.
What Are The Common Semi-Permanent Hair Color Ingredients?
Typically, semi-permanent color formulas include:
- direct dyes (pre-formed pigments)
- conditioning agents
- stabilizers (to maintain color consistency), and
- oils or moisturizers.
To identify the semi-permanent pigments, look for a color name and number, for example: Yellow 2, Red 33, and Blue 1.
Is Semi-Permanent Hair Color Safe?
On the one hand, a semi-permanent hair dye is generally considered safer to use than a permanent dye. This is because it doesn’t contain corrosive alkaline agents such as ammonia or ethanolamine. Additionally, the hair dye substances used in semi-permanent hair colors are milder than those in permanent hair colors. However, even some semi-permanent hair coloring products may contain extreme, strong or moderate sensitizers, which can cause allergic reactions even after repeated use. Therefore, I encourage you to always check the ingredients of your shade.
In my Permanent Hair Color Rating List that assesses more than 60 hair colors for safety, I included one semi-permanent hair color that has proven to be almost as effective as a permanent hair color. This hair color is ammonia-free and ethanolamine-free. Plus, it doesn’t contain any of the extreme sensitizers (e.g., PPD, TDS) or resorcinol.
How Long Does Semi-Permanent Hair Color Last?
Normally, semi-permanent color lasts for 4–12 shampoos, depending on the formula and your hair’s porosity. Conversely, demi-permanent hair color can last up to 24 shampoos, making it a great middle ground between temporary and permanent options.
Permanent Hair Color Vs Semi-Permanent Hair Color: What’s Right For You?
When choosing between permanent and semi-permanent hair color, consider your goals and lifestyle.
Go permanent if:
- You need long-lasting gray coverage or a dramatic color transformation.
- You don’t mind regular root touch-ups and are comfortable committing to a specific shade.
Go semi-permanent if:
- You’re experimenting with new colors or enhancing the tone of your hair.
- You want a gentler, lower-commitment hair color option.
For those seeking versatility, demi-permanent hair dye strikes a balance, offering longer-lasting results without the full permanence.
Whether you’re opting for a bold new look or subtle enhancements, understanding the differences between permanent and semi-permanent hair dyes will help you make the right choice. Remember that no hair color is safe in absolute terms, so do your best, take care of your natural hair color, and enjoy yourself!
To learn more about permanent hair colors, check out my reviews of Madison Reed hair color, Aveda hair color, Tints of Nature hair color, Oway hair color, and Natulique hair color. Consider plant-based hair color options and download my Permanent Hair Color Rating List that reviews more than 60 permanent hair colors for safety.
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