Does a humidifier really help with allergies? Humidifiers are great for relieving allergy, cold and flu symptoms. However, if your humidifier isn’t cleaned properly it can actually worsen these symptoms. Allergy symptoms worsen when dry air enters your nasal passages so a humidifier can help add moisture into the air and help you skip scratchy nasal passages during the winter season.  If you have severe allergy symptoms you may benefit more from a cool-mist humidifier.