Changes in Smell Can Be a Sign of COVID-19 and Lyme Disease
Changes in smell have been described in both COVID-19 and Lyme disease. Sudden loss of smell became widely recognized as a hallmark symptom of COVID-19, but disturbances in smell have also been reported in patients with Lyme disease and other neurological conditions.
According to Parma and colleagues, “A sudden loss of smell and taste is consistent with the now typical presentation of COVID-19 symptoms, making it highly probable that COVID-19 infection is the main reason for these smell and taste changes.” [2]
Patients with other illnesses, including Lyme disease, frequently report changes in smell. An impaired or heightened sense of smell has been described in patients suffering from neurological disorders such as Alzheimer’s and Parkinson’s disease, autoimmune diseases, fibromyalgia, and Lyme disease. [3–5]
A decreased sense of smell (hyposmia) has been described in patients diagnosed with fibromyalgia. These patients had “significantly lower thresholds of smell compared to healthy controls,” writes Amital and colleagues. [4]
Meanwhile, another study found that 50% of 16 patients with Lyme disease experienced hyperosmia (heightened sense of smell), compared with none of the 18 control subjects. [5]
“The high prevalence of this olfactory disorder found in our study suggests the need for further studies of olfactory function in Lyme disease,” conclude the authors. [5]
[bctt tweet=”The loss of smell reported in COVID-19 patients is also seen in Lyme disease.” username=”DrDanielCameron”]
Fallon and colleagues also described sensory hypersensitivity in Lyme disease patients, including photophobia, sound sensitivity, touch sensitivity, and disturbances of taste and smell.
“Foods may taste abnormally sour and bitter,” Fallon writes. “Smells may seem overly intense and noxious.” [6]
Other chemosensory disturbances
Parma and colleagues found that COVID-19 patients can experience more than simple loss of smell. The chemosensory system refers to the body’s perception of chemical signals through smell and taste.
“These results show that COVID-19–associated chemosensory impairment is not limited to smell, but also affects taste and chemesthesis,” the chemical sensitivity of the skin and mucous membranes. [2]
However, qualitative smell disturbances were relatively uncommon. Only a small percentage of participants reported distorted smells (parosmia) or phantom smells (phantosmia).
Additional chemosensory disturbances include:
- Anosmia: loss of the ability to detect one or more smells
- Hyposmia: decreased sensitivity to smells
- Ageusia: loss of taste
- Hypogeusia: reduced ability to taste
- Parosmia: distorted perception of odors
- Dysgeusia: distortion of the sense of taste
- Phantosmia: smelling odors that are not present
- Phantogeusia: metallic or salty taste in the mouth without a stimulus
Editor’s note: It is important to consider Lyme disease during a COVID-19 evaluation when patients present with unexplained changes in smell.
For a comprehensive overview of the Long COVID and Lyme disease connection—including my peer-reviewed research on 889 patients—see Long COVID and Lyme Disease: What Patients Need to Know.
Related Articles:
Long COVID and Lyme Disease: What Patients Need to Know
9 ways COVID-19 and Lyme disease can look alike
Study finds hearing loss and tinnitus common in patients with Lyme disease
Central sensitization syndrome worsens Lyme disease symptoms
References:
- Sutherland S. Mysteries of COVID smell loss finally yield some answers. Scientific American. Nov 18, 2020.
- Parma V et al. More Than Smell—COVID-19 Is Associated With Severe Impairment of Smell, Taste, and Chemesthesis. Chem Senses. 2020;45(7):609-622.
- Perricone C et al. Smell and autoimmunity: a comprehensive review. Clin Rev Allergy Immunol. 2013.
- Amital H et al. Olfactory impairment in patients with fibromyalgia. Immunol Res. 2014.
- Puri BK et al. Hyperosmia in Lyme disease. Arq Neuro-Psiquiatr. 2014.
- Fallon BA et al. The neuropsychiatric manifestations of Lyme borreliosis. Psychiatric Quarterly. 1992.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
Symptoms • Testing • Coinfections • Recovery • Pediatric • Prevention
Glad I saw this. I’ve been getting phantom smells of cigarette smoke starting from March 2022. I’ve never had COVID, but I was treated for Lyme Disease in Aug 2021 & then seemed to have a resurgence of Lyme symptoms after a Moderna booster in early December 2021 (muscle & nerve pain, spasms, increased brain fog, depression, etc.)
I hope you get an answer soon.
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