3 Ways to Treat Loss of Smell From Covid-19
A doctor outlines potential approaches
At first glance, anosmia, or loss of smell, may seem like a trivial consequence of Covid-19 when compared to the other vital organ systems that can be affected. However, smell plays a key role in our daily lives and can easily be taken for granted until it’s suddenly gone.
Of the five senses, smell is the one most closely associated with memory and emotion. Smell is practical. It tells us when a peach is ripe, when the milk has gone bad, and when we need to bathe. Simply put, smell is important. When a disease like the novel coronavirus takes it away, we understandably want it back. I’ll cover some potential ways that can be accomplished, but first let’s examine how infection and smell are related.
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SARS-CoV-2 isn’t the first pathogen to cause anosmia. Common cold viruses such as the rhinovirus and some of the other coronaviruses trigger inflammation of the sinus tissue, called sinusitis, which can lead to loss of smell. Bacteria can also cause sinusitis. Bacterial sinus infections are sometimes treated with antibiotic medications, but unfortunately antibiotics don’t work in treating viral infections.
The novel coronavirus is especially damaging to a human’s sense of smell because the surface proteins SARS-CoV-2 binds to in order to enter our body’s cells happen to be abundant on the smell receptors of our nasal passages. As a result, the virus can easily penetrate and destroy our cells responsible for detecting fragrances. Anosmia frequently occurs early in the course of illness and, in some cases, is the only Covid-19 symptom a patient may experience.
A recent prospective study of more than 200 patients with impaired smell or taste related to Covid-19 showed that four weeks into the illness, 49% recovered their sense of smell or taste, 41% experienced improvement, and 11% had persistent loss of the sensation. An associated commentary was published in July by Joshua Levy, MD, MPH, an otolaryngologist at Emory University in Atlanta. Levy recognized that because of the sheer number of patients already diagnosed with Covid-19 in the United States, those 11% with persistent symptoms could represent more than 70,000 people. Rather than waiting it out for weeks or months, many of these individuals are proactively searching for ways to recover their sense of smell. Let’s talk about three strategies that may work.
Scientific research on the treatment of post-infectious smell loss is limited when it comes to common, long-standing respiratory pathogens. The research is even more limited with regard to SARS-CoV-2, which infected its first human less than a year ago. So, for the most part, we are left to follow the guidance of doctors and medical providers who treat similar conditions on a regular basis.
Experts, including Dr. Levy, postulate that the approach to treatment should begin with interventions thought to improve the loss of smell associated with other respiratory viruses. Chief among these are nasal steroids, which the British Rhinological Society now recommends as first-line treatment for anosmia in patients with Covid-19.
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Steroids are potent anti-inflammatory drugs. When administered topically, as with a nasal spray, steroids act only at the site of application, and thus have very minimal side effects on the body as a whole. Some of this family of drugs, which includes fluticasone and triamcinolone, among others, are available over the counter.
One disadvantage is that nasal steroids are not fast-acting and often take a few days before achieving full anti-inflammatory effect. Nasal steroids also don’t work if they are administered incorrectly. It’s easy to accidentally spray the nostrils in a manner that causes the medication to trickle from the nose to the throat without being absorbed by the nasal mucosa. The key is to tip the head forward and aim away from the nasal septum that divides the nostrils.
Antihistamines and other allergy-related medications
Some experts approach the problem akin to how they treat sinusitis related to seasonal allergies or other types of allergies, also known as allergic rhinitis. Allergic rhinitis creates some of the same symptoms as Covid-19, including runny nose, postnasal drip, cough, nasal congestion, and anosmia. It would stand to reason, then, that medications used to treat allergic rhinitis may also help with the nasal symptoms of Covid-19. The goal here is also to reduce inflammation.
Non-sedating antihistamines, such as loratadine and cetirizine, are available over the counter and have relatively few side effects. Furthermore, medications commonly prescribed for patients with allergies and asthma, such as montelukast and theophylline, carry the potential for benefit. In a prospective study performed prior to the pandemic, investigators followed more than 300 patients with anosmia — about one-third of whom lost their smell because of an infection. Treatment with the asthma medication theophylline was shown to improve sense of smell in 50% of this cohort.
Smell plays a key role in our daily lives and can easily be taken for granted until it’s suddenly gone.
Smell training is a strategy developed and increasingly researched over the past decade to treat loss of smell from head injuries as well as viral illnesses. Rather than being considered a cure, smell training is thought to amplify the body’s natural mechanism of recovery. Scientific evidence suggests smell training may indeed be an effective mode of therapy for smell loss. For example, research using brain imaging with functional MRI indicates that smell training with poignant aromas like that of cinnamon, vanilla, orange, and banana can alter neural pathways in individuals with post-viral anosmia.
The technique of smell training often makes use of essential oils (individually or in kits of a few aromas) to prompt sensory response. Patients open a jar of a particular scent and focus on their memory of that smell for at least 20 seconds while attempting to minimize distractions or other thoughts. They then move on to the next scent. A full course of training repeats this activity twice daily for several weeks.
While it remains apparent that more studies are needed in the field of smell training, as well as other methods of treating Covid-19-related anosmia, it is encouraging to consider the many avenues of potential therapeutic intervention.