Diffusing is an easy and effective method to apply essential oil for many conditions, such as respiratory infection, cold or flu. The essential oil molecules get transported into the nasal passages and subsequently into the bloodstream.

However, not all essential oils or blends are appropriate for a diffuser: Price can make it impractical to diffuse certain oils e. g. Rose or Melissa. Thick or very viscous oils such as Patchouli, Myrrh, etc. will clog your diffuser. Intense oils like Cinnamon or Clove should only be diffused in appropriate blends or high dilution as they can quickly become overwhelming. Essential oils containing ketones like Mugwort and Thuja which should only be inhaled sparingly and for a brief periods of time.