How does contact dermatitis occur? What do you need to know about contact dermatitis?

Contact dermatitis is an inflammatory reaction that occurs at the contact site or even outside the contact site after the skin or mucous membrane comes into contact with exogenous substances once or multiple times. So what do you need to know about contact dermatitis?

1. Occurrence of contact dermatitis

There are mainly two ways. One is that the contact material is irritating, such as strong acids, strong alkalis and other chemical substances or venoms, which directly lead to an inflammatory reaction of the skin. Anyone can get this disease, which is called irritant contact dermatitis.

The other is that the contact material itself is not irritating or toxic, and can activate the immune cells in the body through multiple steps. Contact dermatitis may occur when the body comes into contact with the corresponding antigen again. Most people do not become ill after contact, but a small number of people may experience inflammatory skin reactions. The occurrence and severity of dermatitis are related to the individual's susceptibility and the allergenicity of the contact material. Sensitization occurs 4 to 20 days after the first contact (i.e., being sensitive to it), and a reaction may occur 24 to 48 hours after the next contact. This condition is called allergic contact dermatitis.

Sometimes it's a bit of both.

2. Contact dermatitis tips

1. What are the factors that cause contact dermatitis?

There are many substances that cause contact dermatitis, which can be divided into three types according to their nature: animal, plant and chemical. Common animal toxins include animal toxins or poisonous hairs of insects, such as bees, jellyfish, chiggers, mosquitoes, butterflies, moths, mulberry caterpillars and pine caterpillars; plant toxins include leaves, stems, flowers, fruits or their products of certain plants, such as sumac, nettle, pyrethrum, ginkgo, psoralea corylifolia, etc.; chemical substances include metals and their products, daily necessities, cosmetics, topical medications, pesticides and deodorants and various chemical raw materials.

2. What are the characteristics of irritant contact dermatitis?

Irritant contact dermatitis is caused by a direct toxic reaction to the contact substance, which is highly irritating or toxic. Specifically, it can be divided into two types. One is high-concentration, highly irritating or highly toxic substances such as strong acids and alkalis, animal toxins or insect poisonous hairs. Anyone who comes into contact with a certain concentration and for a certain period of time will develop acute dermatitis at the contact site. The other type is long-term contact with weak irritating substances, such as soap, laundry detergent, gasoline, motor oil, etc., which are mostly caused by repeated contact over a long period of time. Most cases of hand dermatitis among housewives belong to this category. If the skin is exposed to excessive moisture, water, heat, cold, pressure or friction for a long time, it is more susceptible to the disease, while dry and thick skin is less likely to develop the disease.

3. Does allergic contact dermatitis have an incubation period?

Yes, but often there is no reaction after the first contact, and a reaction only occurs after the second contact with the same substance. The incubation period for stronger allergens is only 2 to 3 days, while for weaker allergens it can be as long as several years. After re-exposure to the allergen, symptoms usually appear within 12 to 96 hours, but there are also cases where the disease occurs within 1 hour or a week after contact.

4. Can the allergen of contact dermatitis be found?

Generally speaking, the symptoms of irritant contact dermatitis are more acute, and most people know what irritant caused it, while allergic contact dermatitis often only appears after another contact, and it is difficult to find out what the allergy is. At this time, a patch test can be performed to possibly identify the allergen.