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Smell training

A simple, evidence-based daily exercise that can help recovery after smell loss.

If you have lost your sense of smell, smell training can help recovery. It is a simple, safe daily exercise that exposes your olfactory system to the same set of scents in a structured way. The technique was first published by Professor Thomas Hummel in 2009 and remains the intervention with the most consistent evidence for improving smell after viral infection, head injury, or loss with no clear cause.

Why it works

Smell training takes advantage of the natural ability of the olfactory system to recover, called neuroplasticity. Olfactory neurons are unusual in that they renew themselves throughout life. Repeated, focused exposure to specific scents helps them re-establish connections with the smell-processing parts of the brain. People who train consistently for at least 12 to 16 weeks tend to perform better on objective smell tests than those who do not. Improvement is usually gradual.

Why smell training is the most evidence-based intervention for post-viral smell loss.

Who it is for

  • Reduced or distorted smell for two weeks or more
  • Smell loss after a viral infection (including COVID-19), head injury, or chronic rhinosinusitis
  • Persistent parosmia (smells that seem distorted or unpleasant)
  • Idiopathic smell loss with no clear cause

It is also a useful adjunct after nasal surgery, to support recovery of smell affected by the operation or by long-term inflammation.

What you will need

A smell training kit containing four jars of essential oils: rose, lemon, clove and eucalyptus. These four were chosen to represent four broad odour categories (floral, fruity, spicy and herbal). The brand matters less than using the same four scents consistently. Scent Recover (scentrecover.com) is recommended by the smell-loss charity CKOS. Keep the jars somewhere convenient so twice-daily use becomes a habit, and store them closed in a cool, dark place.

Chrissi Kelly shows how to assemble a smell training kit if you cannot buy one ready-made.

How to smell train

Set aside about five minutes, twice a day, somewhere quiet. For each scent in turn:

  • Hold the jar about 2 to 3 cm from your nose
  • Take quick, gentle sniffs ("bunny sniffs") for around 20 seconds
  • Concentrate fully on the scent, and picture its source. This mindful attention trains your brain as much as your nose
  • Close the jar, rest for a few breaths, then move on to the next scent

How long it takes

Train every day for at least four months. Do not stop early even if you notice no change in the first few weeks. Most people who improve do so gradually over several months, and some benefit from continuing for six to twelve months or longer. Switching to a second set of scents (for example menthol, vanilla, lavender and orange) after the first 12 weeks helps some people; ask me about this if you have trained for several months without progress.

What to expect

  • Improvement is usually gradual and uneven; you may notice everyday smells before the training jars
  • Parosmia (distorted smells) often gets worse before it gets better, which is part of recovery
  • Not everyone responds. Earlier training, within the first six months, tends to give better results, but it is still worth trying in long-standing cases

Tips for success

  • Consistency matters more than effort: two short sessions a day every day beats long, irregular ones
  • Keep a brief diary, rating each scent out of 10 once a week, to see slow changes
  • Treat any underlying nasal inflammation; continue any sprays or rinses I have prescribed
  • If foods bring no pleasure, sticking with them helps you notice when smell starts to return
What to expect when progress stalls, and how to keep going.

If smell training does not work

Other options can be considered, including a short course of corticosteroids where appropriate, investigation and treatment of underlying chronic rhinosinusitis, vitamin A drops in selected cases, and platelet-rich plasma (PRP) injections to the olfactory cleft, an emerging treatment I offer for selected patients. We will discuss your options together.

Useful resources

  • CKOS (ckos.co.uk): courses, events and community support for smell disorders
  • Scent Recover (scentrecover.com): smell training kits following the CKOS protocol

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This guide is general information and not a substitute for individual medical advice. Contact the practice if you have questions about your own care.