Restoring Your Sense of Smell and Taste After COVID-19

Restoring Your Sense of Smell and Taste After COVID-19

A lost ability to smell or a change in the way odors are perceived is called olfactory dysfunction (OD), which also significantly impacts the ability to taste. Reduction in the sense of smell is called hyposmia, and a total inability to smell is called anosmia. A complete inability to taste anything is called ageusia, which is rare.

Traditional treatment for olfactory dysfunction often focuses on receptors in the sinuses or on the tongue. In other cases, it involves olfactory retraining — which involves sniffing different scents daily to restore the pathways to the brain. You can think of olfactory retraining as physical therapy for restoring function to the nerves that carry signals from the olfactory receptors to the brain.

Unfortunately, these treatments don’t work for COVID-19-related olfactory dysfunction because the problem isn’t with the receptors themselves or the pathway that carries sensory information to the brain. The problem is found in the brain, so it makes sense that treatment needs to focus on diagnosing and treating issues associated with the brain.

(Above: Original image © Patrick J. Lynch, medical illustrator)

Bottom line? It’s not so much about treating taste and smell as it is about finding the underlying causes and treating them.

Tracking COVID-19’s Impact on Taste and Smell

The virus named “SARS-CoV-2” and the disease it causes, named coronavirus disease 2019 (COVID-19), affects everyone differently. At one extreme are patients who have no symptoms. In the middle, according to the Journal of Internal Medicine, about 80 percent of people infected with the virus have a mild reaction, and most recover within two weeks. At the other extreme are those who have a severe response and take about three to six weeks to recover. Some of these patients require hospitalization. Mortality rates vary greatly around the world, with the United States experiencing a case fatality rate of a little more than 2 percent, meaning two out of every 100 confirmed cases may result in death.

Approximately 10 percent of patients are long haulers, meaning their symptoms linger for months after they no longer test positive for the infection. The most common symptoms are cough, tightness in the chest, shortness of breath, headaches, muscle aches, diarrhea, brain fog, and fatigue.

In addition, nearly 86 percent of COVID-19 patients lose their ability to smell and taste totally or to some degree, with nearly 95 percent of those patients recovering these senses within six months of having the illness.

Exploring the Causes of Olfactory Dysfunction

Olfactory dysfunction can usually be traced back to one of the following common causes:

  • Sinus infection
  • Sinus allergies
  • Nasal polyps
  • Deviated septum (when the thin wall separating the nasal passages is displaced to one side)
  • Common cold
  • Smoking
  • Influenza (the flu)
  • Exposure to chemical irritants
  • Chronic congestion not caused by allergies (nonallergic rhinitis)

Most of these underlying causes are due to a physical swelling or blockage in the sinus passages that inhibits or prevents odors from reaching the olfactory receptors located higher up in the sinuses. As soon as the swelling or blockage is removed, the ability to smell and taste is typically restored.

However, olfactory dysfunction may also be caused by more serious conditions that disrupt the pathway that carries sensory information from the sinuses through nerves to the brain. This pathway can be damaged or disrupted due to a wide range of causes, including the following:

  • Alcoholism (long-term)
  • Alzheimer’s disease
  • Brain or head trauma or brain surgery
  • Brain tumors
  • Diabetes
  • Epilepsy
  • Hormonal problems
  • Huntington’s disease
  • Malnutrition, including vitamin deficiency
  • Mast Cell Activation Syndrome
  • Medications, including some antibiotics and high-blood-pressure medications
  • Multiple sclerosis
  • Parkinson’s disease
  • Radiation therapy
  • Schizophrenia
  • Stroke
  • Underactive thyroid

COVID-19-related olfactory dysfunction falls into this second group of causes. It’s not due to a problem with smell receptors in the sinuses or taste receptors on the tongue; it has to do with issues associated with the brain.

How We Diagnose & Treat Brain-Related Olfactory Dysfunction

Here’s what we do at Restoration Healthcare to diagnose and treat the underlying cause(s) of brain-related olfactory dysfunction:

  • Neuro function analysis: We assess neuro function and physiology through a functional neuroscience exam using RightEye’s Brain Health EyeQ Diagnostic, Balance Tracking System testing, Automatic Nervous System testing, and Cambridge Brain Science diagnostics as part of the process.
  • BBB breach: We look for a blood-brain barrier breach through various lab tests. In particular, we’re looking at calcium-binding proteins and zonulin (a protein that modulates the permeability of tight junctions between cells of the wall of the digestive tract). These proteins have a close correlation with leaky gut syndrome — a condition in which gaps form in the wall of the digestive tract allowing allergens and toxins to enter the bloodstream and trigger an immune response, which can lead to a host of inflammatory conditions. Leaky gut syndrome can cause harmful substances to enter the bloodstream and cross the blood-brain barrier to reach the brain.
  • Autoimmune markers: We may choose to run a Cyrex test/array that can identify early autoimmune markers that affect taste and smell.
  • Pathogens and toxins: We look for pathogens (viral, bacterial, and parasitic) and toxins (from mold and Lyme disease), that can trigger olfactory dysfunction — especially if other systems of the body are weak.
  • Glycemic control: We may assess glycemic control — your body’s ability to control blood sugar levels. The Hemoglobin A1C test offers a reflection of the last 90 days of sugar and inflammation levels, which can be helpful in determining what caused the loss of taste and smell in the first place.
  • Hormone levels: We may assess hormone levels — especially testosterone because higher levels of testosterone are inflammatory to the brain.
  • Mast Cell Activation Syndrome (MCAS) screening and testing: MCAS — a condition characterized by recurring symptoms such as hives, swelling, low blood pressure, difficulty breathing, and diarrhea, all due to the episodic release of abnormally high levels of mast cell mediators — may also play a contributing role in the loss of taste and smell. As a result, we may also screen and test for MCAS.
  • Brain-derived neurotrophic factor: We assess brain-derived neurotropic factor (BDNF) because it offers a marker that reflects the brain’s ability to heal. The BDNF protein — which is found in the regions of the brain that control drinking and eating — is thoughts to contribute to the management of functions related to taste and smell.
  • Heavy metals: Finally, we assess heavy metal toxicity, which can tie up the brain and impact the senses of taste and smell.

As you can see, the plan of care for restoring the sense of smell and/or taste is based entirely on what we discover through testing. Treatments vary considerably and must be individualized to target the specific underlying causes. Treatment for one patient may require detox and nutritional supplements, while another patient may benefit more from treatments to restore gut health and calm the immune system.

Take Action to Restore Your Sense of Taste and Smell

If you’ve lost your sense of smell or taste to COVID-19, you can wait for several weeks to months for it to return, and hopefully, it will. To ensure your recovery and accelerate it, we encourage you to visit a functional medicine practice near you for a full workup to identify and address the underlying causes.

If your lost sense of smell or taste isn’t related to COVID-19, we encourage you to have it checked out by a qualified medical professional — it could be an early warning sign of a serious condition. The sooner you address the underlying issues, the better the outcome.


Disclaimer: The information in this blog post about restoring your sense of smell and taste after COVID-19 is provided for general informational purposes only and may not reflect current medical thinking or practices. No information contained in this post should be construed as medical advice from the medical staff at Restoration Healthcare, Inc., nor is this post intended to be a substitute for medical counsel on any subject matter. No reader of this post should act or refrain from acting on the basis of any information included in, or accessible through, this post without seeking the appropriate medical advice on the particular facts and circumstances at issue from a licensed medical professional in the recipient’s state, country or other appropriate licensing jurisdiction.