Moisture has a great effect on your health for many purposes. Both humidifiers and dehumidifiers help maintain ideal levels of moisture inside your homes. For instance, using a dehumidifier is best for asthmatics as they are easily irritated by too much moisture. Because excess moisture enhances the growth of mold. On the other hand, using a humidifier relieves you from cold, sinus congestion, and skin dryness by keeping you hydrated.