Most types of hair dyes cause skin allergies, which are caused by one of the chemicals that make them, but the most common cause of allergic reactions is Par-phenylenediamine or PPD, which is found in most commercially manufactured hair dyes, as the latter is usually mixed With the peroxide in the dye to change the hair color, so what happens before this dye reaction is completed, makes PPD more likely to interact with the skin, causing an allergic reaction. 
Another common chemical found in hair dye is Para-Toluenediamine (PTD), which is lighter than PPD and is better tolerated, but may cause an allergic reaction in many people as well. 
Symptoms of hair dye allergy
Hair dye allergy to PPD can be summarized in the following points: 
- An allergic dermatitis caused by contamination of the skin with PPD, as the affected skin becomes irritated, inflamed and red in color.
- The scalp, neck, ears, or chin are affected by sensitivity, and they will become red and inflamed.
- Redness of the eyes, and swelling of the eyelids may occur as the reaction develops.
- The occurrence of spots and itching in various parts of the body.
- Respiratory problems, such as wheezing and sneezing.
- Difficulty swallowing.
Dry and frizzy hair
Continuous use of hair dye causes hair to dry, itchy scalp, and it may lead to hair breakage and breakage due to the strong chemical components that make up it, so the Food and Drug Administration prohibits the use of hair dye on the eyebrows or eyelashes, because this may cause severe sensitivity in the eye. 
Change the hair structure
The dye changes the structure of the hair, and the great damage to it, for example, the bleaching stage, in which harsh chemicals are used to obtain the most light colors, lead to the removal of the natural hair dyes in the hair shaft, which causes damage and fall, and this is according to what trichologist Mirmerani said. "Bleaching changes the structure of the hair, making it more vulnerable to damage," he said. 
- , Jon Johnson (Thu 5 January 2018), "What ' You shouldnt Know About Hair Dye Allergies" , www.medicalnewstoday.com The , Retrieved 28/3/2018. Edited.
- KRISTEEN CHERNEY (JULY 18, 2017), "What Is Worse, a Perm or Hair Dye?" , Www.livestrong.com , Retrieved 28/4/2018. Edited.
- Heather Hatfield, "8 Ways You're Damaging Your Hair" , www.webmd.com , Retrieved 28/4/2018. Edited.