We use one for my daughter. Although she doesnt have CF she does have allergies & gets nose bleeds a bit after using the heat in the house begins. It works great for her, but keeping it clean is a pain in the butt. Between the water elements & animals etc....it accumulates junk easily. As long as I keep it clean its fine & works well. I dont use one for myself, but I keep the window cracked at night. Drives my hubby nuts, but I need the cooler air to breath well. Lots of controversy over humidifiers, but I think its an individual decision & know that using it properly is key.