Hyposmia is a reduced ability to detect odors. It’s not a complete loss of smell (that’s anosmia), but a noticeable decline where scents you once picked up easily now seem faint or absent. About one in five adults over 60 has hyposmia, and the condition becomes increasingly common with age.
How Hyposmia Differs From Other Smell Disorders
Smell disorders fall along a spectrum. Hyposmia sits in the middle: you can still detect some odors, but your sensitivity is clearly diminished. Anosmia, by contrast, means you can’t smell anything at all. A third condition, parosmia, distorts your perception so that familiar smells become unrecognizable or unpleasant. You can have more than one of these at the same time, and hyposmia can progress to anosmia if the underlying cause worsens.
What Causes It
The most common causes fall into a few broad categories: nasal and sinus problems, infections, head injuries, aging, and neurological conditions.
Chronic sinus inflammation (rhinosinusitis), especially when nasal polyps are present, is one of the leading causes. Inflammation does more than just block airflow to the smell receptors in your nose. Research using animal models has shown that inflammatory molecules can directly impair and even kill the specialized nerve cells responsible for detecting odors. Prolonged inflammation causes lasting damage to the tissue lining the upper nose where those neurons live.
Viral infections are another frequent trigger. Many people first notice reduced smell during or after a cold, flu, or COVID-19 infection. In most cases, the loss is temporary, but for some people it lingers for months or becomes permanent. The virus can damage the delicate nerve cells in the nasal lining, and while the body does have the ability to regenerate those cells, recovery isn’t always complete.
Head trauma can cause hyposmia by stretching or tearing the thin nerve fibers that pass from the nose into the brain. Normally, stem cells in the nasal lining can replace damaged smell neurons, but if the injury also affects deeper brain structures or causes scarring inside the skull, new nerve fibers may not be able to reconnect properly. This is why smell loss after a head injury is often persistent.
Age-related decline, sometimes called presbyosmia, happens when the body gradually loses its ability to maintain a healthy population of smell neurons. Studies of nasal tissue from older adults show a patchwork pattern where smell-detecting tissue has been replaced by ordinary respiratory tissue that can’t sense odors. This reflects a breakdown in the repair system that normally regenerates smell neurons throughout your life.
The Link to Parkinson’s and Alzheimer’s
A declining sense of smell can be one of the earliest signs of Parkinson’s disease and Alzheimer’s disease, sometimes appearing years before the more recognizable symptoms like tremors or memory loss. This happens because the disease process begins in the brain’s smell-processing areas before spreading to regions that control movement or cognition. Not everyone with hyposmia will develop a neurodegenerative condition, but a sudden or unexplained decline in smell, particularly in older adults, is worth discussing with a doctor.
How Common It Is
Hyposmia is far more prevalent than most people realize. In a large study of community-dwelling adults aged 60 and older, the overall rate of hyposmia was about 20.5%. The numbers climbed steeply with age: roughly 16% of people in their 60s had hyposmia, about 25% of those in their 70s, and 29% of those 80 and older. When anosmia was included, more than half of people over 80 had some form of smell impairment.
A small number of people are born with reduced or absent smell. Congenital anosmia affects about 3% of people with lifelong smell loss and can occur on its own or as part of a genetic syndrome like Kallmann syndrome, which also affects hormonal development. Researchers have so far identified only nine genes linked to isolated congenital smell loss, compared to over a hundred genes associated with inherited vision and hearing problems.
How It’s Diagnosed
Doctors typically assess smell function using standardized scratch-and-sniff tests. The most widely used is the University of Pennsylvania Smell Identification Test (UPSIT), a 40-item test where you scratch a panel, sniff, and choose from multiple-choice options. Scoring thresholds vary slightly by sex. For men, a score of 34 or above is normal, while 30 to 33 indicates mild hyposmia and 26 to 29 suggests moderate hyposmia. For women, normal is 35 and above, with mild hyposmia at 31 to 34 and moderate at 26 to 30. Scores of 19 to 25 for either sex indicate severe hyposmia, and 18 or below points to total anosmia.
These tests help quantify the degree of loss, but your doctor will also want to investigate the cause. That might involve examining the inside of your nose with a scope, ordering imaging to check for polyps or structural issues, or running neurological evaluations if there’s no obvious nasal explanation.
Treatment Options
Treatment depends on what’s causing the smell loss. When chronic sinus inflammation or nasal polyps are the problem, corticosteroids are the primary approach. Topical steroid sprays or rinses are commonly used and carry relatively low risk. For more significant polyp-related smell loss, a short course of oral steroids can provide initial improvement, though the benefit is often temporary unless followed up with ongoing topical treatment. Doctors weigh the potential side effects of oral steroids carefully and discuss them before prescribing.
For hyposmia caused by viral infections, options are more limited. One emerging approach uses a calcium-buffering nasal solution (sodium citrate), which appears to work by removing calcium ions in nasal mucus that may interfere with smell signaling. In clinical trials, a single application provided temporary improvement in patients with post-infection smell loss. The effect didn’t last long, but it could offer brief windows of improved smell during activities like eating.
Olfactory Training
The most broadly recommended therapy, regardless of cause, is olfactory training. The standard protocol involves sniffing four distinct scents twice a day for at least 24 weeks. The classic set uses rose, eucalyptus, lemon, and clove. You hold each scent close to your nose and sniff steadily for 20 to 30 seconds, concentrating on trying to detect and identify the odor. The idea is to stimulate regeneration and rewiring in the smell-processing pathways, similar to physical therapy for an injured muscle. Morning sessions before breakfast and evening sessions before bed tend to work best.
Olfactory training requires patience. Six months is the minimum recommended duration, and some people continue for a year or more. Results vary, but it remains the best-supported non-medical treatment available.
How It Affects Daily Life
Living with reduced smell has consequences that go well beyond missing the fragrance of flowers or fresh coffee. In a large survey of people with smell disorders, 85.9% reported significant safety concerns. Gas leaks, spoiled food, and smoke were the top worries, and those concerns are justified: over a five-year period, about 32% of participants experienced at least one food-related safety incident, 34.5% had at least one gas scare, and nearly 15% had an actual gas incident.
The emotional toll is also substantial. Research consistently links smell loss to social isolation, negative emotions, and depression. Food loses much of its appeal when you can’t smell it, which can lead to changes in eating habits, poor nutrition, or excessive use of salt and sugar to compensate for missing flavor. Work-related incidents affected 18.5% of people in the survey, highlighting that the impact extends into professional life as well.
Practical adaptations can help reduce risk: installing natural gas detectors, checking food expiration dates carefully, using visual cues for cooking, and asking others to confirm whether something smells off. These steps don’t restore what’s missing, but they address the most dangerous gaps that a reduced sense of smell creates.