In tiny amounts mold isn't harmful. However, a tiny amount of mold can quickly increase if the right conditions arise. Mold growth can ruin walls, furniture, fabrics, etc. but more importantly it can make you sick. People who are allergic or sensitive to mold can experience nasal stuffiness, eye irritation, wheezing, skin irritation, headache, and fatigue. People with chronic respiratory illnesses can develop mold infections in their lungs. While folks suffering from asthma can experience mold triggered asthma attacks. Even if you are healthy and don't have mold allergies, exposure to large amounts of mold can result in severe reactions including fever and shortness of breath.

If you observe mold in your home immediate remediation efforts should be taken. Small areas of mold can be cleaned with a biocide, such as bleach. Large areas of mold growth can be dangerous and professional cleaning is recommended.