Anosmia is the inability to perceive odor or a lack of functioning olfaction – known simply as “the loss of the sense of smell.”
One of the questions we get asked from time to time in our Facebook group is, “My nose isn't working due to my cold – are essential oils going to work from me?” Or, “My husband was born without a sense of smell – is he going to benefit from the essential oils I'm diffusing?”
The short answer is: yes, the essential oil constituents physically present in the air that are inhaled can have therapeutic effect.
Let's take a closer look at the olfactory system to understand why…
As you can see by this image (source), the olfactory system is made up of several parts. When we smell essential oils – or any aroma – the molecules we are inhaling make their way from the the olfactory cells to the olfactory bulb. The olfactory system works closely with the brain to give both psychological and physiological impact. If the olfactory nerve is damaged, or the part of the brain which processes aromas, the signal ends which makes it impossible for essential oils to have an effect.
Temporary loss of smell due to colds and other illness may prevent the psychological therapeutic properties of essential oils from working, but they will still work on a physiological level.
For example: if you have associated the aroma of Lemon essential oil with fresh summer days (psychological level working here), but have anosmia, diffusing Lemon essential oil may not be useful for you (although the fine print here is that Lemon does have anti-depressant therapeutic properties so could have some effect). If you are congested, diffusing an anti-congest blend like this one (link to recipe) can help you on a physiological level.
Conclusion: there are still benefits to diffusing essential oils, even if you can't smell them.