Hair dye can be divided into three types: temporary hair dye, semi-permanent hair dye, and permanent hair dye. It has the effect of changing the color of the hair. Temporary hair dyes are hair dyes that require only one wash with a shampoo to remove the color from the hair. Since the particles of these dyes are large and cannot enter the hair shaft through the epidermis, they are only deposited on the surface of the hair, forming a coloring layer. Semi-permanent hair dyes are generally those that can withstand 6-12 shampoo washes before fading. Semi-permanent hair dyes are applied to the hair, left on for 20-30 minutes, and then rinsed with water to color the hair. It is more popular in recent years because it does not require the use of hydrogen peroxide and does not damage the hair. Permanent hair dyes are divided into three types: plant permanent, metal permanent, and oxidation permanent.
Patients suffering from high blood pressure, heart disease, asthma and other diseases should not dye their hair, in addition, couples preparing to have children and pregnant and breastfeeding women are also not suitable for hair dyeing.