What Is That Smell? Lyme Disease and Heightened Sensitivity
Lyme disease may affect more than joints, fatigue, and cognition—it may also alter the sense of smell. Some patients report a heightened sensitivity to odors, a condition known as hyperosmia, which is only beginning to be explored in Lyme disease.
Changes in smell have long been associated with neurological disorders such as Alzheimer’s and Parkinson’s disease. More recently, researchers have begun investigating the connection between olfactory disorders and autoimmune diseases, suggesting a broader link between immune dysfunction and sensory changes.
Although many Lyme disease patients have described unusual sensitivity to smells, formal research in this area has been limited—until recently.
A study found that 50% of Lyme disease patients reported heightened sensitivity to smell.
Study Finds Increased Sensitivity to Smell
Researchers evaluated olfactory function in a small group of participants:
- 16 patients with confirmed Lyme disease
- 18 control subjects
The findings were notable:
- 50% of Lyme disease patients reported hyperosmia
- No control subjects reported similar symptoms
The study was published in the Arquivos de Neuro-Psiquiatria.
The authors concluded that the high prevalence of olfactory changes warrants further investigation, including whether hyperosmia improves with treatment.
Patient Reports Support the Findings
In an informal Facebook poll, 86% of respondents reported changes in their sense of smell after being diagnosed with Lyme disease.
While not a controlled study, these findings suggest that sensory changes may be more common than currently recognized.
Comparison With Other Conditions
Interestingly, other chronic conditions are more commonly associated with the opposite problem—a reduced sense of smell (hyposmia).
For example:
- 42% of patients with fibromyalgia experienced hyposmia
- 15% of patients with systemic sclerosis reported reduced smell
- Only 4% of healthy controls had similar findings
These differences highlight how various diseases can affect sensory pathways in distinct ways.
Why This Matters
Changes in smell may seem minor, but they can significantly affect daily life.
Heightened sensitivity to odors can interfere with eating, sleep, concentration, and overall quality of life.
More importantly, these symptoms may reflect underlying neurologic or inflammatory processes associated with Lyme disease.
Clinical Perspective
Lyme disease is a multisystem illness with a wide range of neurologic and sensory manifestations.
Hyperosmia may be part of the broader neurologic picture—even though it is not widely recognized in standard diagnostic frameworks.
Clinicians should consider sensory symptoms when evaluating patients with suspected Lyme disease.
Further research is needed to better understand the mechanisms behind olfactory changes and their response to treatment.
Dr. Daniel Cameron, MD, MPH
Lyme disease clinician with over 30 years of experience and past president of ILADS.
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