Mold allergies are the result of a mistake by your immune system. When you breathe in the spores that mold releases to reproduce, your body thinks it's being invaded. In response, your immune system produces antibodies to fight off the allergens. Among the chemicals produced in the process is histamine, and it's responsible for most of your allergic symptoms.
Among these allergic symptoms are rashes; your skin can become dry and scaly if you're allergic to mold and you breathe it in, or you might develop hives. However, mold can cause skin reactions without you being allergic. If you're sensitive to mold, your mucous membranes can become irritated when you come in contact with it. As a result, you might find that your skin becomes irritated. Mold can also cause a skin infection that isn't allergy-related. In addition, a "toxic reaction" to mold mycotoxins that you eat or drink can result in skin irritation, as well.