11 February 2020 What is contact dermatitis? Contact dermatitis results from an allergic reaction to substances that contact the skin . It is characterized by itching , redness and small vesicles at the site of contact with this substance, that appear over the time of exposure. Lesions can range from minor to severe and can be disabling to perform a specific profession. Commonly, the substances that cause contact dermatitis are chemical compounds present in paints, dyes, varnishes, rubbers, leather, cosmetics or daily hygiene products, such as deodorants or shampoos. Who can have contact dermatitis? There seems to be a genetic predisposition for the development of contact dermatitis. Atopic dermatitis can also be a risk factor for the development of contact dermatitis. Some specific professions are more often associated with this disease due to repeated exposure to certain types of chemical substances, for example: hairdressers; beauticians; metallurgical; locksmiths; bakers; florists; caregivers of children or the elderly. In other cases, contact dermatitis is not associated with a specific profession and can occur with everyday products such as: cosmetics; detergents; disinfectants. What causes contact dermatitis? Contact dermatitis results from an exaggerated response of the immune system to an innocuous substance , usually a chemical substance, that contacts with the skin. How is the diagnosis of contact dermatitis made? The diagnosis is based on a detailed clinical history , namely on which chemical compounds the patient is exposed to, either in the workplace, during hobbies or even at home. It is useful to carry out contact tests (epicutaneous tests or patch tests) to identify the substance that causes dermatitis. These tests consist of placing patches on the back with small quantities of substances that could potentially cause allergy. After 48-72 hours the results are read. If they are positive, there is a small allergic reaction in the area. How is contact dermatitis treated? If it is possible to identify the causal agent, it should be avoided. It is very important to deliver to the patient and, if necessary, to the employer a list of which compounds cause the dermatitis. For the treatment it is recommended the use of moisturizing creams , as well as creams or ointments that reduce skin inflammation (topical corticosteroids and immunomodulators). The authors of this text are the following allergologists from the Hospital da Luz network: Luís Miguel Borrego, Ana Morais Mendes, Ana Reis Ferreira, Andreia Ferrão, Carlos Braga, Cristina Lopes, Diana Pereira da Silva, Filipa Semedo, Isabel Costa Silva, João Gaspar Marques, Pedro Carreiro Martins, Marta Salgado, Nuno Sousa, Rosa Anita Fernandes, Susana Piedade The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
