When we talk about contact dermatitis, there are two types of contact dermatitis. One is an irritant contact dermatitis, the other is allergic contact dermatitis.
Irritant contact dermatitis happens when you come into contact with something irritating. For example, if all of us touch some dilute acid, it is going to irritate our skin, so that is a contact allergy because we come into contact with the acid which irritates our skin.
Then we have allergic contact dermatitis, where the substance you apply on the skin sensitises the skin and causes you to mount an immune response. For example, things like nickel allergy where you wear nickel earrings and it causes itching because the nickel is something you are sensitised to.
Hair dye allergic Is also another form of allergic contact dermatitis and PPD is the main ingredient in hair dyes that triggers this eczema. So, if you do have allergic contact dermatitis, the most important thing is to avoid the allergen, avoid the things that are triggering it.
You can sometimes do a patch test, where we stick multiple chambers containing different ingredients on the back to try and see if we can identify the allergens you are allergic to. Common things are nickel, certain preservatives, hair dyes. These are common allergens where we can do a patch test and it is important to avoid the allergens.
