Should You Wash Your Hair Before Dyeing It?

Since your hair has a direct impact on your appearance, coloring it can be a high-stakes decision. When it comes to dyeing your hair, there's homework to do to make the most informed decision possible. Some questions that might come to mind about hair dyeing are: Should I color my hair at home with a boxed hair dye or go to a professional? Should I ask for a refund if my hair doesn't achieve the exact color I ordered?

However, if you're new to hair coloring, whether or not you should wash your hair before dyeing it may be the least of your concerns. Until your scalp has experienced an hour or so of a burning sensation while waiting for the color to develop, you might not realize the importance of prepping your hair for coloring. Some hair dyes have skin-irritating chemicals, which cause the surface of your scalp to sting and give it an itchy rash, per Head and Shoulders. While harsh skin reactions to hair dyes are common, you can keep them to a minimum. One of the biggest favors that you can do to your scalp the day before altering your hair hue is to not wash it, L'Oréal Paris points out. Here's why.

Hair dyes contain ingredients that can irritate your skin

Hair dyes contain various ingredients that, when sitting on the hair for any length of time, may cause varying degrees of skin irritation. Most allergic reactions to hair coloring products are caused by an oxidative chemical known as paraphenylenediamine (PPD), according to Dermnet NZ. The reactions, while common, can range from mild to intense depending on the sensitivity of your skin, from a brief rash on the scalp to a swollen face. If the reaction becomes severe and lingers hours after coloring, you might need medical attention. In rare cases, per National Health Service, hair colorant can trigger anaphylaxis, a potentially life-threatening allergic reaction. 

To know if you have PPD sensitivity, take a patch test by dabbing a small amount of the colorant that contains PPD behind your ear or on your inner elbow and keep an eye on the area for two to three days. Do not use the product if you have rashes or other signs of discomfort following the patch test. Instead, opt for PPD-free hair dyes. Whether you intend to color your hair by yourself or go to a hair colorist, check the product labels for irritants and allergens that might give your scalp a hard time before working the dye into your hair.

Don't head into a hair dye with freshly washed hair

Once you've tested your sensitivity to certain ingredients in hair dyes, prep your hair for coloring. "Your hair should be dirty because the natural oils help to protect against the harsh chemicals," says hair colorist Terri Fe to "The grease serves as an extra coating so that when we go to break down the cuticle, there's less damage and breakage to the hair and irritation to your scalp." So technically, dirty hair makes the burning sensation from hair dye less intense. This rule of thumb works for both virgin hair and touch-ups. Besides, since you'll get a thorough hair wash after your color treatment anyway, a skip of hair wash beforehand will save you some shampoo and conditioner.

Nonetheless, L'Oréal Professionnel artist and colorist Katie Collette suggests that there isn't an all-encompassing answer to the question of whether or not you should wash your hair before a color treatment. It all depends on the color of your choice. "Anytime you are wanting to deepen your color or add lowlights, clean hair offers the most accurate read of your natural color," Collette told Hair. For bright, colorful hair shades that need a decent amount of bleaching, you can skip a wash or two before a color treatment. Knowing what sets off your sensitivity and avoiding colorants that cause allergic reactions are crucial whether you have your hair colored at home or at a salon. It's best to discuss the color you want and your skin condition in advance with your colorist and to obtain expert advice on how to care for your hair both before and after a hair dye.

Should you wash your hair bleaching it?

You should refrain from washing your hair with even a mild shampoo for at least two days prior to your appointment. This is because washing removes natural oils from your hair, which are necessary to preserve your hair shaft during the bleaching process.

Therefore, you don't want to remove this layer of defense before your hair has been exposed to toxins. Additionally, bleaching has a stronger effect on your hair than coloring does. Bleaching is capable of removing the melanin within the hair while dyeing only alters the color of your hair. Besides, while dyeing can be temporary or permanent, bleaching is typically permanent and cannot be washed away.

If you have to wash your hair the night before for no other reason than convenience, condition your hair with coconut oil after washing, and keep the conditioner on for the duration of the night to fortify your hair and minimize any potential harm from bleaching the following day. If your hair has been dyed, you shouldn't bleach it until eight weeks minimum have passed, but you should definitely equip it with a deep conditioning treatment a week before your bleaching appointment. 

Avoid using certain hair products before your appointment

"A good thing to do the day before coloring is to use a clarifying shampoo to remove any product buildup, and to help even the hair's porosity so color takes evenly," Oscar Blandi Salon's lead colorist Kyle White tells Everyday Health. "You should follow that with a deep conditioner to replace any moisture that may be lost during coloring." A hydrating hair mask that freshens your hair with decadent nutrients is also good to use before a coloring appointment.

You should avoid using dry shampoo because it has the potential to alter the color effect you're going for. Although dry shampoos, particularly ones with wax or tint, don't negatively affect color-treated hair, they may compromise the efficacy of the dying process by stopping dye from penetrating the hair, according to Better Not Younger. As a result, you might get a color that's one or two shades lighter than what you expected or uneven patches here and there. If you use dry shampoo, make sure you rinse all the product out prior to the dye job to enhance your hair color.

How long should you wait to wash your hair after dyeing it?

Technically speaking, a hair wash is part of the dyeing process, so there's practically no need to re-wash it the moment you get home. Even if you want to, you shouldn't. According to Colored Hair Care, you should wait for at least 24 hours after the coloring treatment to start washing your hair because running your freshly colored hair under water can cause the color to fade and your hair strands to dry out. The longer you can go without using the faucet, the better. If you want to wash your hair 24 hours after the treatment, opt for a gentle cleansing shampoo sans sulfates and gently massage the product into your hair instead of aggressively scrubbing it. For rinsing, opt for cold or lukewarm water as opposed to hot water to prevent the hue from softening.

You'll also want to shampoo less after a dye job. Shampooing three to four times per week rather than daily can help you keep the natural oils that maintain your color-treated hair, preserving its vibrance. If your hair feels greasy and dirty, you can refresh it with dry shampoo instead. Since color-treated hair is more prone to dryness and breakage, it's typically recommended to use shampoos and conditioners specifically designed for color-treated hair to keep your tresses hydrated and help your color last even longer.