Aromatherapy to Improve Abnormal Sense of Smell and Taste From Long COVID

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Ms. Chen, 29, is one of the many people to suffer lingering symptoms long after being infected with COVID-19. After the virus seemingly cleared her system, she was left without a sense of smell and she continued to tire easily.

Dr. Lee Choi-Keung, a traditional Chinese medicine (TCM) physician at Taiwan Jinhe Traditional Chinese Medicine Clinic, found that Ms. Chen had a thick tongue coating and a weak spleen and stomach. Dr. Lee prescribed Xanthii fructus powder, supplemented with Lycium formula, Acori tatarinowii rhizoma, and Asari radix et rhizoma for resolving phlegm and warming the lungs.

After taking the medicine for about four days, the patient regained some sense of smell. After a week, more potent scents became detectable.

Current Western treatments for loss of taste and smell are based primarily on olfactory training (a rehabilitation method). TCM has long used similar techniques.

But TCM also offers additional treatments based on insights passed down for generations that provide therapeutic options even for new diseases, such as long COVID. TCM approaches for long COVID focus on its connections to the lungs, spleen, and kidneys.

The right treatments can restore the senses of smell and taste, but because these senses can require regrowth in the nervous system, it can take some time to see results. Patients should seek medical assistance as soon as possible, but there is no need to panic.

Long COVID

According to the World Health Organization, as of August, more than 769 million people worldwide have been diagnosed with COVID-19. About 10 percent to 20 percent of these people continue to suffer with long COVID long after their initial infection.

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Common symptoms include fatigue, shortness of breath, abnormal taste and smell, cough, brain fog, chest pain, and muscle pain.

Studies have shown that among all COVID-19 patients, 40 percent to 50 percent of people worldwide report symptoms of olfactory and taste disturbances. In objective tests, up to 98 percent of people show a decline in olfactory function.

According to a meta-analysis published in the British Medical Journal in 2022, disturbances of smell and taste manifest mainly as decrease or loss, abnormality, a sense of rancidity, or even hallucinations.

Researchers conducted 18 randomized studies on 3,699 patients. The results showed that 74.1 percent of patients recovered their senses of smell within 30 days, and 85.8 percent recovered it within 60 days. For sense of taste, 78.8 percent of patients recovered it within 30 days, 87.7 percent within 60 days, 90.3 percent within 90 days, and 98 percent within 180 days.

The researchers found that women with more severe loss of smell and nasal congestion early in the infection were less likely to recover. Additionally, although most patients can expect to regain their sense of smell or taste within three months, most will experience long-term dysfunction.

How Does COVID-19 Affect Smell?

A study published in December 2022 in Science Translational Medicine, a sister journal of Science, revealed the main reason for the loss of smell after COVID-19 infection.

Researchers analyzed olfactory epithelium samples collected from 24 biopsies, nine of which were from patients with long-term loss of smell after infection with COVID-19. Samples from these nine patients showed extensive CD45+ immune cell infiltration and inflammatory responses in their olfactory epithelium.

Although the samples showed they were free of the COVID-19 virus, inflammation persisted, and the number of olfactory neurons was significantly reduced. This showed that the viral infection causes an abnormal immune response in the human body, which continues to destroy the olfactory neuron cells in the nose, causing a massive reduction of those cells and resulting in loss of smell. This is why recovery requires regrowth of these neurons.

Aromatherapy

Dr. Li Jialing, an aromatherapist with dual licenses in TCM and Western medicine and the director of the Fuqian Traditional Chinese Medicine Clinic, said on NTDTV's "Health 1+1" program that people with smell or taste disorders should first address nutrition and avoid greasy food. People can also use essential oils (EOs), such as citrus, eucalyptus, patchouli, German citrus, rosewood, and real lavender, to help restore their senses, with different EOs selected according to different personal constitutions.

"When sniffing essential oils, it is not recommended to use a type with 100 percent concentration because it will be very irritating to the sense of smell. Long-term exposure to such high-concentration EOs will reduce the sensitivity of smell," Dr. Li said.

"It is best to add some carrier oils, such as sweet almond oil or sunflower oil, among others, diluted to 5 to 10 percent. When this concentration improves the sense of smell, then lower the concentration; during the process, keep lowering the concentration and try to see if you can smell it; if you can smell it, it means that the sense of smell is gradually recovering."

Recent research in the United States also shows that smelling EOs can help patients recover their sense of smell faster. Researchers selected four essential oils of rose, lemon, eucalyptus, and clove for a three-month experiment with adults who had lost their sense of smell because of COVID-19 infection. They discovered that having study participants view pictures of corresponding smells while smelling EOs promoted the recovery of the sense of smell to a certain extent.

Regarding the restoration of taste, Dr. Li said that different EOs can be applied during the treatment's early, middle, and final stages. For the early stage, employ small-molecule EOs, such as citrus essential oils, and in the final stage, use large-molecule resinous EOs, such as rock bluegrass, sandalwood, frankincense, or patchouli. The choice of oils will depend on different personal constitutions. After that, adjust the smell and sniff the small and large molecule EOs daily.

*Note: Some of the herbs mentioned in this article may sound unfamiliar, but many are available in health food and Asian grocery stores. Because everyone's physique differs, please consult a professional physician for specific treatment options.