As with many skin conditions, the exact causes of eczema are unknown, although experts believe that it may be caused by the immune system's overactive response to certain triggers [source: WebMD]. Asthma and hay fever are other atopic diseases, so people with a family history of these conditions are likely to be affected by atopic dermatitis.
Though the scientific cause of eczema is unknown, it's fairly easy to identify some of the more common causes of eczema flare-ups in adults. Substances that cause burning, itching or redness are often sources of flare-ups. Common irritants include rough materials such as wool, household products such as soap or detergent, or fumes from paint or cigarettes. It really depends on what your immune system responds to.
Allergens like animal dander and dust mites can also spark a flare-up. If you're allergic to certain types of food, you may have a short bout of eczema. However, it can be difficult to pinpoint exactly which food it is that's causing the outbreaks. To find out what might trigger your eczema, see your doctor. A doctor can do a skin test, where he or she touches the skin with the possible allergens and observes the reaction, or conduct blood work to find what you're allergic to, if anything. Both of these tests may have false positive reactions, so they are not always reliable [source: National Eczema Association].
Exposing your skin to certain environmental conditions may also result in flare-ups. Sudden changes in temperature or humidity, sweating, upper respiratory infections and colds commonly trigger eczema. And though stress and emotional disorders don't cause eczema, they can worsen its effects. Although there is no cure for eczema, it is not contagious, so don't worry about contracting it from or giving it to others [source: National Eczema Association].
To find out how to treat eczema symptoms and what to do if your skin becomes infected, keep reading.