In a recent article, UC Davis Health’s Dr. Toby O. Steele discusses his treatment protocol for patients suffering from loss of smell after recovering from COVID-19.  About 5-10% of patients will have lingering symptoms of reduced or altered ability to smell and taste after recovering from this viral infection. The loss of smell can actually have profound effects on an individual’s health including their nutrition, weight, and even safety in emergency situations like fires. In Dr. Steele’s protocol he is combining two methods – olfactory training and intranasal budesonide. His protocol attempts to treat two separate mechanisms by which loss of smell occurs – the conductive pathway and the neural pathway.

How Does Loss of Smell Occur?

There are a variety of reasons why olfactory impairment can occur. The condition can be related to a viral infection, medication, trauma, or environmental exposure and sometimes the cause is unknown. It is estimated there are at least 200 possible causes for olfactory impairment, although most reported cases are due to sinonasal disease and viral infection. The most commonly discussed cause of olfactory impairment right now is post-viral infection related to COVID-19.

Loss of olfactory functioning following an infection actually can occur with many types of viral infection, but the widespread nature of the pandemic has given the issue a new focus. Between 5-10% of patients will deal with olfactory impairment that continues for weeks, months, or longer after recovering from COVID-19.  Right now it is not known how long the impairment could last. Some patients will start to notice their sense of smell returning a few months post-recovery and others may spontaneously notice an improvement after that.

As discussed in a previous blog regarding the use of intranasal theophylline for treating loss of smell after COVID-19, olfactory impairment has been considered a diagnostic criteria for detecting infection. Measuring the sudden onset of loss of smell in a population can be a good predictor of the spread of the virus if the information can be obtained.

Is Loss of Smell Serious?

Yes, loss of smell is serious for those experiencing it. While it may seem like it is written off as just a lingering symptom of viral infection, it can actually have profound effects on a person’s quality of life and their safety. For example, without a sense of smell it is difficult to detect if there is a fire or something burning on the stove. The smell of a gas leak is also undetectable. The effect on taste makes food less palatable and can cause nutritional deficits and weight loss. For these reasons and more, loss of smell is something that needs to be managed and treated.

What is Budesonide?

Budesonide is a corticosteroid that is used intranasally to treat chronic rhinosinusitis and other sinonasal conditions. In other oral and inhaled forms it is also used to treat Crohn’s disease, asthma, COPD, allergies, and ulcerative colitis. Its effectiveness is due in most cases to its ability to reduce inflammation.  Many symptoms of nasal conditions are related to inflammation of the nasal passages and sinuses. Budesonide has a low risk of over dose, although there are some side effects and drug interactions to consider. Many patients are eligible to try using this medication after consulting with their healthcare provider.  

Can Budesonide Help with Loss of Smell?

In a 2018 study of 133 patients, researchers concluded that: “Adding budesonide irrigation to olfactory training significantly improved olfactory ability compared with olfactory training plus saline irrigation.” In the budesonide group, 43.9% improved and results were better in patients who were young or who had more recent olfactory loss. Both the treatment group and placebo group received olfactory training throughout the study.

Budesonide was first tried as a treatment for loss of smell because it is thought that many types of olfactory impairment are associated with inflammation. A corticosteroid used for various nasal and sinus conditions, budesonide can decrease inflammation in conditions like chronic rhinosinusitis. For this study of 133 patients, any cases where the patient had an underlying inflammatory nasal disease were excluded. This helped confirm that the benefits of budesonide were due to olfactory improvement not just treating an underlying chronic nasal condition.

When combined with olfactory training, budesonide may provide a better nasal environment for an effective retraining of the sense of smell. Olfactory training is simple but it requires compliance with a consistent schedule of training to be effective. The training usually involves smelling several different scents on a daily basis to re-train the nose how to smell. In a study that lasted 12 weeks, patients were told to expose themselves to 4 intense odors each day, which were provided by the researchers. These odors included eucalyptus, lemon, and cloves. After 12 weeks, the treatment group had improved olfactory function compared to the control group which had no improvement.

The protocol of budesonide and olfactory training outlined by Dr. Steele targets two different mechanism of smell loss. The conductive pathway is being treated with the budesonide – this is the part of the impairment that affects the olfactory receptors in the nasal cavity. The neural pathway is being treated with the olfactory training – this is the part of the impairment where the brain’s ability to recognize signals from the scent receptors is affected.

Irrigation vs. Nasal Spray

Both budesonide irrigation and nasal sprays may be used to treat nasal conditions. The most common type of budesonide available at pharmacies is a nasal spray. While this may be effective, it is possible that an irrigation provides better coverage of the nasal passages. Nasal irrigations have been shown to be more effective at treating the posterior or superior nasal cavity compared to nasal sprays.

More Than Just a Smell Loss Treatment?

A clinical trial has shown that budesonide may benefit people over age 50 with COVID 19 symptoms. In the trial, inhaled budesonide (like the inhaler used to treat asthma) was found to shorten recovery time by a median of three days in patients with COVID-19 who are at higher risk of more severe illness. The trial included 751 people in the budesonide group and 1028 in the usual care group who were SARS-CoV-2 positive. Since budesonide for inhalation is widely available throughout the world and is inexpensive, this provides a promising way for  clinicians to help manage early COVID 19 in their communities.

Articles

Inhaled budesonide in the treatment of early COVID-19 (STOIC): a phase 2, open-label, randomised controlled trial – The Lancet (opens in new window)

Budesonide irrigation with olfactory training improves outcomes compared with olfactory training alone in patients with olfactory loss – Allergy & Immunology (opens in new window)

Effects of olfactory training in patients with olfactory loss – Laryngoscope (opens in new window)

Olfactory Dysfunction in COVID-19 Diagnosis and Management – JAMA Insights (opens in new window)

Inhaled Budesonide – PRINCIPLE TRIAL (opens in new window)