Hair coloring involves the use of chemicals that penetrate the hair shaft and alter its natural color.
The most common types of hair dyes are permanent, semi-permanent, and temporary.
Permanent hair dyes use a combination of ammonia and hydrogen peroxide to lift the hair cuticle and deposit color molecules.
Semi-permanent hair dyes do not contain ammonia and only deposit color on the surface of the hair shaft.
Temporary hair dyes are the least damaging and only coat the outside of the hair shaft.
While hair coloring is generally safe, it can cause allergic reactions, hair damage, and even increase the risk of cancer in some cases.