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Olfactory training is a non-pharmacological and non-surgical treatment option for patients with olfactory dysfunction. Patients undergoing olfactory training expose themselves to 4 different odors twice daily for at least 24 weeks. The main indications include post-infectious, post-traumatic, and idiopathic olfactory dysfunction and olfactory dysfunction due to COVID-19 or Parkinson disease.


About 20% of people in the general population have an impairment of the sense of smell. Impaired olfaction leads to diminished quality of life. It can be dangerous, as environmental hazards such as the smell of natural gas or smoke may not be appreciated; the sense of taste is intimately connected with the sense of smell, and diminished taste can also result in missed indications of danger, such as spoiled or contaminated food. Furthermore, impaired olfaction may be a warning sign for common neurodegenerative disorders, such as Alzheimer's dementia, Parkinson disease or COVID-19.

Beside medications, there's also a non-surgical and non-pharmacological approach to improve olfactory function is olfactory training, wherein patients expose themselves twice daily to different odors over the course of several months.

Before carrying out olfactory training, the patient must perform a thorough physical examination of the nose to look for possible etiologies. Then, an objective examination of the olfactory function was carried out using the sniffin' sticks test, to determine the baseline of the patient's olfactory function before therapy was carried out. Patients also need to be given an understanding that this olfactory exercise is not short/instant, so there is no need to feel disappointed if progress is slow.



Olfactory training requires different types of odorants, The odors for training are presented in sniff bottles or jars. The most commonly used odorants are lemon (fruity), rose (floral), cloves (spicy) and eucalyptus (resinous). Why these four scents? most people can identify the five different tastes that humans are capable of detecting: salty, sweet, bitter, sour, and savory (umami). Some researchers have also tried to categorize the many different smells as well. These categories include floral, fruity, spicy, resinous, burnt and foul. Instead of having to practice smelling burnt or foul odors, this training concentrates on the more pleasant smells from the other four categories. The four odorants stimulate different receptor patterns in the olfactory nerves. Don't forget to set up a timer to set the length of the training.


For standard olfactory training, the patients sniff twice daily (preferably once in the morning before breakfast and once in the evening before going to bed). These olfactory training should be made into a daily habit, for a minimum of 12 weeks.

The procedure for olfactory training is as follows:

  1. Patients were asked to assess by themselves about their olfactory function before olfactory exercises were carried out
  2. The patient sits in a quiet place without distraction
  3. Open the odorant bottle and hold the cap near the nose. Sniff the cap slowly, for 20-30 seconds
  4. Remind the patient to concentrate on this process. Focus on the odorant you are smelling, for example if you are smelling a lemon, then focus your mind on the lemon and previous experiences with lemon
  5. Keep the odorant out of your nose and try to breathe for several cycles. There are no specific provisions regarding the lag time between odorants
  6. Repeat this process for the other three odorants

Always record every training result/progress for evaluation. Do not smell the liquid directly from the bottle, because the essential oil will risk irritating the skin if exposed directly.

This training is believed to work as a combination of the unique ability for smell nerves to regrow while encouraging improved brain connectivity.


Typically, patients undergo olfactory training for at least 24 weeks. For patients with post-infectious olfactory dysfunction, olfactory training over the course of one year yielded better results than training for 16 weeks. For patients with hyposmia or anosmia without a history of sinonasal infection, olfactory training, following the standard protocol (that is, olfactory training with four different odors twice daily for at least 24 weeks), might be a good starting point.


After 12 weeks, evaluate the success of the olfaction exercises by:

  1. Subjective, from individual training records
  2. Objective, by conducting tests in the clinic using the sniffin' sticks test. Compare the results with individual training records

Patients can also be scheduled for control to the clinic at intervals of several weeks, to increase patient compliance in carrying out olfactory training. At each meeting, evaluate with history and physical examination to assess the patient's olfactory function.




  1. National Institutes of Health. (2022). Olfactory Training
  2. ENT Health. (2021). Smell Retraining Therapy
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