Steam treatment carries essential oils directly to sinuses and lungs, and provides warm, moist air to help open nasal and bronchial passages. Boil about 4-6 cups (1-1.5 liters) of water, turn off the heat, let it cool for 1 minute. Carefully pour the water into a large bowl or just use the same pan the water was heated in. Add 3-6 drops of an essential oil to the water and use a towel to guide the steam around your head as you breathe deeply.

If steaming is impractical, inhale from a tissue to which a few drops of an essential oil have been added. Commonly-used oils include eucalyptus, mint, wintergreen, cajuput, frankincense, juniper and menthol.

An aromatic diffuser disinfects the atmosphere by releasing droplets of essential oil as a cool, fine mist. It can be turned on in a room for 10 to 15 minutes every hour to clear airborne bacteria. Because of clogging, do not use thick oils in a diffuser unless they have been diluted with a thin oil such as citrus, eucalyptus or rosemary, or mixed with alcohol. If oils are left too long in a diffuser, they can oxidize and thicken.

Diluted essential oils can also be used as a throat spray through "nebulization". A perfume atomizer or spray bottle will work to create this fine spray. If you don't have a diffuser, simply combine water and essential oils in a spray bottle.