Molds produce irritating substances that may act as allergens (allergy-causing substances) in sensitive individuals. Furthermore, some molds produce toxic substances. Mold may not cause health effects or it may lead to symptoms in people who are sensitive to molds. Allergic reactions to mold are the most common health effects of mold. Allergic reactions may happen immediately or develop after a period of time following exposure. Both growing mold and mold spores may lead to allergic reactions. Symptoms of mold allergy may include sneezing, runny nose, coughing, wheezing, tearing and redness of the eyes, and skin irritation or rash. Asthma attacks may be caused by mold or mold spores in people who have asthma and are allergic to mold. Even in some non-allergic individuals, mold can irritate the eyes, skin, and airways. For example, the “black mold” known as Stachybotrys, along with some other types of mold, produces toxins known as mycotoxins that can cause irritation of the skin and airways in susceptible individuals. In some cases, people may develop severe reactions to mold exposure. Symptoms of severe reactions, which are uncommon, include fever and difficulty breathing. People with compromised immune systems or those with chronic lung disease can develop serious infections of the lungs due to molds. It is not possible to predict the degree of severity of the health risks associated with mold in the home. Allergic individuals vary in their degree of susceptibility to mold, and the risk may also depend upon the extent and exact type of mold that is present. In 2004, the Institute of Medicine (IOM) found there was sufficient evidence to link indoor exposure to mold with upper respiratory tract symptoms, cough, and wheezing in otherwise healthy people. Mold was linked to the worsening of asthma symptoms in people who have asthma. Mold was also reported to be linked to hypersensitivity pneumonitis in individuals susceptible to this immunologic condition. This uncommon disease is similar to pneumonia and can develop in susceptible individuals after brief or prolonged exposure to mold.