The human experience of dying often involves profound sensory changes, including the perception of unique smells. While direct scientific study is limited, anecdotal accounts suggest certain odors may be present near the end of life.
Commonly Reported Olfactory Sensations
Individuals, caregivers, and family members frequently describe distinct smells near the end of life. Hospice workers often report a “stale, sickly sweet” odor, sometimes compared to overripe bananas, vanilla, or marzipan, which can precede death by days or hours. This sweet scent is sometimes described as cloying or musky, and has been linked to liver failure. Other reported smells include a metallic scent, reminiscent of pennies or blood.
Earthy or musty odors, sometimes described as deep, raw, or fungal, are also mentioned. Ammonia-like or bleachy smells are noted as pungent. Less common are fecal or rotten meat odors, especially with underlying medical conditions like certain cancers. These observations are largely subjective, and the specific smell varies greatly depending on the individual and their health status.
Physiological Explanations for End-of-Life Odors
As death approaches, the body undergoes metabolic and physiological changes that produce detectable odors. As organs, particularly the liver and kidneys, begin to fail, the body’s ability to filter waste products diminishes. This leads to a buildup of compounds like ammonia, often associated with kidney dysfunction, creating a bleachy or ammonia-like smell. Liver failure might result in a musty or sweet aroma, or a smell akin to rotting bananas.
When a person stops eating and drinking, dehydration and ketosis can develop. Ketosis, where the body burns fat for energy, produces ketones like acetone, leading to a sweet, fruity, or nail polish remover-like odor on the breath or skin. As tissues break down and bacterial activity increases, compounds such as putrescine and cadaverine are released. These can contribute to unpleasant odors if tissue necrosis or infection is present.
Incontinence can contribute to odors as muscles relax near death. Infections or necrotic tumors, especially in advanced cancers, can also release foul-smelling compounds. These physiological shifts emit volatile organic compounds (VOCs) and other metabolic byproducts, perceived as distinct smells.
The Role of Brain and Perception
Beyond physiological changes, the brain influences smell perception near the end of life. Altered states of consciousness, from severe illness, medications, or reduced oxygen, can affect sensory interpretation. This may lead to perceiving smells without an external source, known as olfactory hallucination or phantosmia. Such hallucinations can be vivid and real.
The brain might misinterpret subtle environmental odors or generate new ones internally. Some individuals report smelling familiar scents, like a deceased loved one’s perfume, a manifestation of brain processing during emotional or cognitive change. Individual brain chemistry and personal experiences significantly influence what, if anything, is smelled.
Distinguishing Fact from Anecdote
Studying sensory experiences at the end of life presents challenges due to the inherent nature of the dying process. Most information regarding smells before death comes from anecdotal reports from caregivers, family members, or individuals themselves. These observations, while meaningful, are difficult to verify through controlled scientific studies. Researchers face ethical complexities and practical limitations in conducting experiments on terminally ill individuals.
Current scientific understanding correlates observed odors with known physiological changes in a dying body. While specific metabolic byproducts like acetone or ammonia can be chemically explained, the broader spectrum of reported smells and their consistent occurrence requires more research. Perceived odors before death are likely a complex interplay of physical transformations, psychological factors, and subjective human perception.