Researchers exploring noninvasive diagnostics are examining whether volatile organic compounds in breath, skin secretions, and urine can signal diseases like Alzheimer’s, cancer, and Parkinson’s. While preliminary associations show promise, experts emphasize that odor changes remain research tools rather than validated standalone tests for independent diagnosis.
Long before modern laboratory instruments, medical diagnosis relied heavily on the human senses. In the fifth century B.C., the Greek physician-philosopher Hippocrates held that disease could be identified by body odor. Modern clinical practice has continued to encounter this phenomenon in informal ways. During her doctoral research at a Norwegian cancer ward, social anthropologist Hanna Marie Ihlebæk found that several nurses depended on their sense of smell while providing routine patient care. Other medical workers noted they could pick out digestive bleeding and cell necrosis simply by scent.
Today, researchers are working to translate those subjective impressions into precise science. Illness alters body chemistry in measurable ways, changing the compounds released through breath, sweat, skin oils, urine, stool, and wounds. Fresh sweat is largely odorless, but body odor develops when skin bacteria break down compounds in secretions. When disease alters metabolism, inflammation, or tissue health, it changes the profile of volatile organic compounds, or VOCs, emitted by the body.
Volatile Organic Compounds and Cancer Detection Research
When tumors grow, oxidative stress inside the body increases. This physiological shift causes fatty molecules within cells to break down into smaller, volatile compounds.
Research teams have begun isolating specific chemical signatures associated with malignancies. In one study investigating lung cancer, scientists tested patient breath before and after surgery to remove lung tumors. The analysis identified 16 compounds that could serve as breath biomarkers, including pentanal, foul-smelling butyric acid, woody hexanal, and decanal, which carries a scent reminiscent of orange peel.
Urine chemistry offers another avenue for noninvasive screening. Woollam and his colleagues analyzed molecules wafting from the urine of men undergoing prostate cancer biopsies and found that a panel of six molecules could detect the disease in 75 percent of cases. While this method is less sensitive than the prostate-specific antigen blood test, the VOC approach produced fewer false positives, potentially helping patients avoid unnecessary medical interventions.
Commercial Development and Regulatory Designations
Rather than searching for a single biomarker, the test uses artificial intelligence to analyze patterns of molecules in urine samples.
The Food and Drug Administration granted the TOBY bladder cancer test Breakthrough Device designation in 2026 to help accelerate its review path, and company developers indicate it is approximately a year away from a commercial launch. The same research team is developing a comparable screening tool aimed at Alzheimer’s disease, which secured the FDA’s Breakthrough Device designation in May.
Sebum Signatures and Parkinson’s Disease Research
Beyond breath and urine, chemical clues to neurodegenerative conditions reside in sebum, an oily and sticky substance produced by tiny glands in hair follicles. Scientists are actively investigating how volatiles emanating from sebum relate to Parkinson’s disease, a condition that frequently receives late diagnoses, leaving patients without properly managed symptoms for extended periods. Olfactory impairment itself serves as an established marker of aging and neurodegenerative disorders such as Alzheimer’s disease and Lewy Body diseases, which include Parkinson’s disease, Parkinson’s disease dementia, and dementia with Lewy bodies, often appearing years before other clinical features emerge, as detailed in data from pmc.ncbi.nlm.nih.gov.
The sebum connection originated through real-world observation. A woman named Joy Milne noticed that her husband’s body odor had shifted to an unpleasantly woody and musky scent years before he received an early-onset Parkinson’s diagnosis. Later attending an awareness lecture, she realized other patients shared that exact scent. This observation led to collaborations with researchers at the University of Edinburgh and the University of Manchester, including Perdita Barran.
If I swabbed your back, I would find about 20,000 compounds. And if you had Parkinson’s, about 2,000 of them — so, 10 percent — would be different to people who don’t have Parkinson’s.
Perdita Barran, Parkinson’s researcher at the University of Manchester
Barran’s team identified specific compounds in sebum, including acyl-carnitines, which shuttle fatty acids into mitochondria for energy production, and other molecules linked to disruptions in fatty acid metabolism. The established sebum signature can correctly identify over 84 percent of individuals with advanced Parkinson’s, and ongoing work explores whether the profile can spot the disease early before clear-cut symptoms manifest.
Current Scientific Limitations and Clinical Realities
Despite promising developments, medical experts emphasize that ordinary body odor cannot diagnose complex medical conditions like Alzheimer’s or cancer. A physiological change may serve as a useful clinical clue, but it does not constitute proof.
From sitting to lying, you change your breath profile. You hold your breath, you change your breath profile. You take a drug, you change your breath profile. … So how do you want to sort that out?
Wolfram Miekisch, chemist at the University Medical Center Rostock
Additional barriers facing the field include extremely small chemical concentrations, differences driven by age, sex, diet, hygiene, and environment, overlapping chemical patterns among different diseases, and machine-learning models that fail outside their specific training datasets. Independent reporting notes that reliable validation requires large and diverse participant groups, comparisons across multiple conditions, standardized sample handling, and long-term follow-up studies. pmc.ncbi.nlm.nih.gov adds that community-based and population studies are particularly vital because they test the external validity of clinic findings and remain less vulnerable to the selection biases often found in clinic and volunteer samples.
Frequently Asked Questions
Can ordinary body odor confirm an Alzheimer’s diagnosis?
No. While researchers are studying whether metabolic and inflammatory changes are associated with neurological disorders, an unusual scent is not a diagnostic test. People experiencing memory loss or cognitive changes require a formal clinical evaluation.
Are electronic noses available for routine medical diagnoses?
Electronic noses and chemical-analysis instruments are currently utilized as research tools rather than validated clinical tests. Healthcare professionals rely on established diagnostic methods to interpret suspected health conditions.
When should a person consult a physician regarding body odor changes?
Persistent or concerning changes in breath, skin, wound, or urine odor warrant professional medical assessment, particularly when accompanied by symptoms such as fever, unexplained weight loss, confusion, breathing difficulties, or severe fatigue.