Smell training is a therapeutic protocol for those who've lost their sense of smell, whereby you actively sniff the same 4 scents (usually essential oils), twice per day, for an extended period of time, with the aim to produce an overall increase in olfactory function.

The aim is to retrain your brain to be able to smell again. A good analogy is if you take someone who’s had a stroke and can’t move their arm. They would go to physical therapy and work on getting their arm to move again. With smell training, you’re working on trying to kick-start the regenerative process that’s inherent to the olfactory system. The goal is to make the correct connections back to the olfactory bulb and thereafter the correct connection back to the olfactory cortex.

The protocol for smell training is sniffing a set of 4 jars (each with a unique scent) twice per day, every day for about 6 months. Each jar is sniffed for 20 seconds with 20 second pauses in between each jar, making each training session 2 minutes, 20 seconds long.
It’s important to train with four distinct odors so that you stimulate different types of olfactory receptor neurons in the nose. The classic scents used in most scientific studies are rose, lemon, eucalyptus, and clove. However, you don’t need to train with these exact odors. Most important is that you have a scent memory of what you train with so you can make the neural-brain connections again.

Almost everyone. One of the wonderful things about smell training is that it's been studied in multiple etiologies (causes) of smell loss, including age-related loss, in trauma-related loss, in post-viral related loss (incl. COVID), and in neurodegenerative diseases such as Alzheimer’s and Parkinson’s. Smell training has proven to be beneficial, at varying degrees, but to some effect, for each of these patient groups, which means that anyone who has smell loss or distortion will most likely benefit from smell training. Only those born with no ability to smell (congenital) will not see any effect.

Start early and be consistent. The sooner you can start the better because, unfortunately, the longer you go without smell training, the less likely you’ll be able to do anything about it at a certain point. Really sticking with it, at the earliest possible moment, for 6 months gives you the best chance of seeing improvement.

The sooner you get started after your initial loss, the sooner you’ll most likely start seeing results. If it’s already been 6 months to a year since you lost your sense of smell, it will probably take that same amount of time to see a major improvement. The key is to be consistent with your smell training and, with time, you’ll start to notice improvements.