How long does it take to reset sense of smell?

I have noticed that when I go on vacation for several days and then come back home, there is a distinctive, relatively mild paint smell in my apartment complex. However, under normal circumstances, this smell is virtually unnoticeable to me.

What are the primary factors that cause us to become used to certain smells? And, is there any way to estimate how long it takes to 'reset' the sense of smell, so that these smells which we have become used to will again be obvious?

Loss Of Taste And Smell: Causes, Diagnosis, And Natural Treatment Options

If you have a cold or cough, the chances are that you have experienced a loss of taste and smell. It may be partial or complete, depending on the severity of your condition. It may also be a common complaint among those who are aged and recovering from serious illnesses, such as cancer.

Many medical conditions can cause a loss of sense of smell and taste. In this article, we will discuss what causes it, the treatment options you can consider, and how you can manage the symptoms by using natural remedies.

Training May Speed Smell's Return After COVID

TUESDAY, Dec. 1, 2020 (HealthDay News) -- Special training may help COVID-19 patients regain their sense of smell after suffering parosmia, a new British study suggests.

Parosmia is a condition where people have strange and often unpleasant smell distortions. Instead of smelling a lemon, for example, you may smell rotting cabbage, or chocolate may smell like gasoline. Parosmia has been linked to COVID-19 and other viruses and head injuries.

"Some degree of smell loss is thought to affect up to one-quarter of the general population," said researcher Carl Philpott, from the Norwich Medical School at the University of East Anglia.

"Smell loss is also a prominent symptom of COVID-19, and we know that the pandemic is leaving many people with long-term smell loss, or smell distortions such as parosmia," he said in a university news release.

Smell training involves sniffing at least four different odors twice a day every day for several months.

"It aims to help recovery based on neuroplasticity -- the brain's ability to reorganize itself to compensate for a change or injury," Philpott said.

The researchers worked with more than 140 people who had lost or had changes in their sense of smell.

The study patients were given a variety of smell training kits -- including different odors, like eucalyptus, lemon, rose, cinnamon, chocolate, coffee, lavender, honey, strawberry and thyme.

"We found that the presence of parosmia and worse smell performance on testing of odor identification and discrimination was associated with clinically significant recovery in smell function for people experiencing post-viral smell disorders," Philpott said. "This means that smell training can help the smell pathways to start to regenerate and recover."

The investigators also found that older people were more likely to start to recover their sense of smell. Also, the biggest improvements were seen among those who had lost the most amount of smell function.

The research was carried out before the pandemic, but the researchers believe their findings could help people who lost their sense of smell due to COVID-19.

The report was published online recently in the journal The Laryngoscope.

Air Aroma

Stop in any perfume shop, and you’re bound to find small bowls of coffee beans set between various fragrances. A salesperson may advise you to sniff the beans in between smelling multiple scents. It is commonly believed that the smell of coffee beans creates some sort of palate cleanser for your nose, allowing you to continue to smell fragrance after fragrance.

But why would someone need to do that? Olfactory fatigue, or olfactory habituation, is a real thing, and it deserves some attention. Essentially, the olfactory glands in your nose begin to recognize smells after a period of time (like the perfume you've been wearing all day), and will stop alerting you to them, making you think there's no fragrance there. It is an example of sensory adaption the body becomes desensitized to stimuli to prevent the overloading of the nervous system, thus allowing it to respond to new stimuli that are ‘out of the ordinary’. Do coffee beans have some magical little molecular component that resets our palate, allowing us to continue to smell things? Turns out, the answer is no! Dr. Alexis Grosofsky of Beloit College’s Department of Psychology has scientifically proven that coffee beans do nothing to cleanse or reset your olfactory palate. Read the full study here.

Maybe you’ve always wondered why the beans were there. This myth has been around for so long that it's nearly impossible to find a fragrance store without coffee beans! But, alas, they do not serve a purpose other than to psychologically distract you. Biologically, we could keep smelling things for hours.

So, what can we use to reset our palates when we’re feeling a bit of olfactory fatigue? The answer may surprise you. The best way to deal with olfactory fatigue is to simply smell your own skin. Perfumers will sniff the crook of their elbows when necessary. You are always performing olfactory habituation to your own smell, so it is a perfect baseline. Leave the coffee beans alone and keep sniffing.

How to Get Your Smell and Taste Back After COVID-19

The first sign of COVID-19 is often the loss of taste and smell, also known as anosmia, and even those without other symptoms have experienced this. Not being able to smell or taste your food can be an alarming realization, but this doesn’t typically last long, and you can help decrease these symptoms from home . Dr. David Rosen, an otolaryngologist at Jefferson Health, spoke with us on why this is happening and how to get your sense of smell and taste back after recovering from COVID-19.

Understanding the loss of taste and smell

Smell loss during and after a respiratory virus isn’t new. Typically, post-viral smell loss includes a runny nose or nasal symptoms. This is not the case with COVID, where the smell and taste loss arrive before any respiratory symptoms. COVID is a unique type of respiratory virus with quick access to the nervous system. Dr. Rosen says that this means that the virus easily travels up the nose and attaches itself to the olfactory nerve, which is at the top of the nose and responsible for conveying sensory information related to smell to your brain.

Dr. Rosen says the most common complaint of those recovering from COVID is that they can smell fine but have lost their sense of taste. After smell testing these patients, they’re only able to smell some of the scents, and they realize they, in fact, don’t have a good sense of smell.

“Generally, people can identify tastes, like sweet, sour, salty, bitter, and umami (savory) , but if you can’t smell, you can’t tell the difference between something like cherry or grape. It just tastes sweet ,” Dr. Rosen says. So , most people are having smell loss, which leads to their loss of the sense of taste. When you eat food, the aroma goes to the base of the tongue, and then it goes up into the nose for you to say, ‘ O h, this is cherry.’”

How to get taste and smell back after COVID-19

Many videos have surfaced online of people trying to trigger their sense of taste with aromatic foods like blackening oranges and eating them or biting into onions like they are apples. While some of these attempts may seem absurd, they may actually work . These unique exercises are similar to those of olfactory training. “ Olfactory training actually utilizes the body’s n e uroplasticity , which is the body’s ability to form new nerve pathways . These methods help the body create new neural pathways and he lp recover t he sense of smell ,” says Dr. Rosen.

There is no wrong time to start trying to trigger your sense of smell and taste to return. If you have COVID or have recently recovered but still have smell and taste loss, Dr. Rosen recommends starting early smell exercises . Alp ha lipoic acid , vitamin A supplements, and over-the-counter steroid nasal sprays may be helpful. O lfactory training can easily be done at home and has been the most helpful in promoting smell fibers to start working again.

Dr. Rosen recommends smelling readily available items around the house and slowly mastering new smells. It’s good to begin smelling coffee, perfumes, citrus, or different types of essential oils—master identifying these and then move on to a new scent. There is no downside to doing these tests, and data has shown that it helps patients recover quickly.

Recovery time

Recovery time varies from patient to patient. While some recover within days, some may take months, and this is why treatment can be tricky. Patients who have lost their smell after COVID may have a side effect of parosmia so that when their sense of smell returns, things can smell very bad to them. Dr. Rosen says that any sign of smell is a good sign of recovery . T his means that some neuro-regeneration is happening, and the smell fibers are just not fully back to normal.

This is when you would want to start doing more olfactory training to help stimulate the olfact ory nerve .

The good news is, the majority of patients recover quickly, so this loss of taste and smell is temporary. If you are still suffering from these symptoms after recovering from other COVID symptoms, start doing more olfactory training and over-the-counter nasal steroid sprays.

Long-term risks

The riskiest part of having no sense of taste and smell is not being able to smell gas. Other issues include it being difficult to cook and eat because the diet becomes more about texture instead of taste. “ P eople become unable to have a normal diet due to everything tasting flat, which results in weight loss issues ,” Dr. Rosen says. Socially, one of the things that connect people is food, which becomes a disconnect when you can’t share the same way with your friends and family.

How a doctor can help

The first thing Dr. Rosen does is perform nasal endoscopy in the office to make sure there isn’t another cause for smell loss. He may prescribe patients with a steroid rinse and possibly oral steroids. At this point, patients are instructed on how to perform smell training exercises. Many COVID patients have previously been prescribed oral steroids for the COVID infection. But additional oral steroids may be helpful. If patients still haven’t recovered after six months, they may be eligible for a platelet-rich plasma (PRP) study. This is where plasma is inserted into the nose through a needle or sponge at the olfactory cleft to trigger a regenerative cell growth process, just as doctors would do to heal scars or encourage hair growth.

If you’re concerned that you lost your sense of smell and were diagnosed with COVID, there is no underlying condition causing this, so you don’t need to worry too much. If it has been months and you are still unable to smell, contact a doctor. It is also important to make sure that there isn’t a more serious cause of the loss of taste and smell. The sooner you pursue treatment options, like a more aggressive medical treatment or olfactory training, the better.

For the latest information on Jefferson Health’s COVID-19 vaccine distribution, visit

Want more information? Tune into The Health Nexus Podcast where Dr. Rosen discusses a clinical trial that uses platelet-rich plasma to help patients get back their sense of smell, and a patient offers her personal experience on this trial and regaining her senses.

What the nose knows

The olfactory system, which allows humans and other animals to smell, is essentially a way of decoding chemical information. When someone takes a big sniff, molecules travel up the nose to the olfactory epithelium, a small piece of tissue at the back of the nasal cavity. Those molecules bind to olfactory sensory neurons, which then send a signal by way of an axon, a long tail that threads through the skull and delivers that message to the brain, which registers the molecules as, say, coffee, leather, or rotting lettuce.

Scientists still don’t fully understand this system, including exactly what happens when it stops working. And most people don't realize how common smell loss really is, Munger says. “That lack of public understanding means there’s less attention to try to understand the basic functions of the system.”

People can lose their sense of smell after suffering a viral infection, like influenza or the common cold, or after a traumatic brain injury. Some are born without any sense of smell at all or lose it because of cancer treatments or diseases like Parkinson’s and Alzheimer’s. It may also fade as people age. While smell disorders aren’t as apparent as hearing loss or vision impairment, data from the National Institutes of Health (NIH) show that nearly 25 percent of Americans over the age of 40 report some kind of change in their sense of smell, and over 13 million people have a measurable disorder like anosmia, the total loss of smell, or hyposmia, a partial loss. Such conditions can last for years or even be permanent.

It’s not clear if COVID-19 anosmia is different from other instances of smell loss caused by a virus, but those who experience anosmia due to COVID-19 appear to be unique in a few ways. First, they notice the loss of the sense immediately because it’s not accompanied by the congestion or stuffiness that generally characterizes the early stages of virally induced anosmia.

“It’s very dramatic,” says Danielle Reed, associate director of the Monell Chemical Senses Center in Philadelphia, which studies smell and taste loss. “People just cannot smell anything.”

Another notable difference is that many patients with COVID-19 who report losing their sense of smell get it back relatively quickly, in just a few weeks, unlike most people who experience anosmia from other viruses, which can last months or years.

Quagge estimates he’s recovered about 60 percent of his sense of smell so far, but he says in the early days, without any information about when or if he’d ever get it back, he was scared. An avid amateur chef, he had to rely on his family to tell him if the milk was bad, and he couldn’t smell his wife’s perfume. “Stuff that gets to your soul,” he says. “It bummed me out.”

Research into restoring loss of smell and taste in COVID patients

Specialist teams at UCLH and UCL are at the forefront of research which could bring hope to people who have been robbed of their sense of smell and taste after suffering the long-term legacy of COVID-19.

Consultant rhinologist Peter Andrews has relaunched the olfactory smell clinic at the Royal National ENT and Eastman Dental Hospitals to investigate patients and health care workers who have been suffering with smell and taste loss following COVID-19 &ndash sometimes with devastating results. The research is part of an international study and leads on from the successful olfactory PhD programme currently ongoing at the UCL EAR Institute.

Some people with COVID-19 lose their sense of smell because the virus damages the olfactory receptor nerve endings or supporting olfactory cells within their nose. It&rsquos not yet known whether the damage will be permanent: potential regeneration could take at least 18 months. The team are also seeing patients who partially recover their sense of smell and taste but instead describe distorted smells and tastes.

In collaboration with the UCL EAR Institute and Professor David Choi UCL Queen Square Institute of Neurology, Mr Andrews will be examining biopsies of damaged olfactory cells following COVID-19 to determine the potential for supporting cells to be transplanted to enable damaged cells to regenerate and reconnect to the central nervous system.

It builds on his success in re-activating olfactory receptors and nerve fibres in the hollow space inside the nose using delicate surgical techniques to straighten the septum which divides the nostrils. This technique hit the headlines seven years ago when one of his patients regained his sense of smell after 40 years.

Peter Andrews said: &ldquoOlfaction (the cells which enable us to smell) is the only part of the central nervous system which can regenerate. They usually regenerate every 6 weeks in the nose to replace receptors that have been damaged by pollution and toxic fumes. However, frustratingly following a viral attack such as flu or COVID-19 this capacity to regenerate is sometimes lost.&rdquo

&ldquoOur aim is to further evaluate this smell loss following COVID-19 infection using cellular techniques and MRI scans. General opinion is that sense of smell and taste is not considered as important as our other senses: however, loss can have far-reaching effects on a person&rsquos quality of life resulting in depression and loss of appetite.&rdquo

The smell clinic has recently been relaunched to investigate growing numbers of cases. At the moment there is no cure. Patients are offered steroid sprays or tablets, zinc and vitamin A supplements and smell training therapy.

In smell therapy, patients are encouraged to sniff a selection of everyday items with clear and distinct aromas including coffee, mint, and rose essence, chocolate. They are asked to identify and differentiate between them to help them &lsquorelearn&rsquo smells. Some patients have total loss of smell (anosmia) others cannot differentiate between different smells. Others &ndash possibly the most unfortunate &ndash smell distorted, disgusting aromas (parosmia).

To access the clinic, patients experiencing post-viral symptoms are encouraged to see their GP and request a referral to UCLH.

Full referral information for GPs

UCLH now has three clinics for patients with long Covid. The main clinic is under respiratory medicine but we also run two specialist clinics for neurological complaints and anosmia.

GPs within North Central London STP can refer through the NHS e-Referral Service and patients will be triaged to the service most suited to help with their symptoms. GPs outside the North Central London STP can use the advice and guidance service on eReferrals. Patients outside North Central London STP can find a clinic closer to home from this list.

To refer a patient to the main clinic on eRS please choose:

· Specialty &ndash Respiratory Medicine

· Clinic type &ndash Not otherwise specified

· Organisation &ndash University College Hospital

· Service name - Post COVID Multi-specialty Follow Up Service - UCLH RRV

To send an advice and guidance request on eRS please choose

· Specialty &ndash Respiratory Medicine

· Clinic type &ndash Not otherwise specified

· Organisation &ndash University College Hospital

· Service name - Post COVID Advice and Guidance Service - UCLH RRV

To refer a patient to the Covid Neurology Clinic on eRS please choose:

· Clinic type &ndash Neuromuscular

· Organisation &ndash National Hospital for Neurology and Neurosurgery

· Service name &ndash Neuromuscular &ndash NHNN &ndash UCLH &ndash RRV

To refer a patient to the anosmia clinic on eRS please document anosmia clearly in the referral letter and choose:

· Organisation &ndash Royal National ENT and Eastman Dental Hospital

· Service name &ndash ENT Nose/Rhinology Service &ndash RNTNE &ndash UCLH &ndash RRV


The CT scan and your specialist have effectively ruled out any infection, illness or blockage as a cause and, as you have no history of trauma, you will understand my conclusion that it is the heavy cold that's to blame.

The technical term for an impaired sense of smell function is hyposmia. Less commonly, some people, like you, are left with an odd smell this is referred to as parosmia.

This suggests that the nerve damage is less severe, which means there's a reasonable prospect of eventual recovery, though the improvement will be slow and may take up to two years.

There is no treatment for impairment of her smell functions

That's because if the problem is due to swelling to the lining of the nose from a cold, it can settle, meaning a passage to the nerve endings will open up again.

If it is due to a head injury, the nerves have usually been severed with no chance of recovery.
So, why have you also lost your sense of taste?

The taste buds are located on the tongue, and also on the soft palate and back of the throat.

They respond to five tastes: sweet, sour, salt, bitter and umami. Everything else about the experience of taste - in essence, the underlying flavour - depends on smell.

This is why loss of your sense of smell has so impaired your enjoyment of eating and drinking.

Unfortunately, there is no treatment for impairment of your smell functions, but at least partial recovery is possible and I hope that will be fortunate.

R ecently, I had a scan of my head as I was suffering with headaches just on the left side. The scan showed I have extensive white matter abnormalities and I was prescribed an aspirin a day, which gave me awful heartburn and wind, so I stopped taking it. Can you tell me what white matter is, and should I worry about these results? My GP told me there could be various causes, but could not tell me what caused mine. I am 75 and apart from the headache - which was not severe but was constant - I am healthy and active, I even have an allotment.

Elizabeth Cosgrave, Birmingham.

PLEASE do not worry overly about this finding: you are healthy and active, and it is almost certainly of no consequence.

The white matter of the brain is made of nerve fibres. It is important for brain function, in that it allows messages to be sent between brain cells, co-ordinating functions between regions of the brain. It acts like a communication circuit.

Grey matter, by contrast, is composed mainly of neurons or nerve cells: the grey matter makes up the parts of the brain involved in the control of muscles, as well as sight, hearing, speech, memory, emotions and a number of other bodily functions.

You have only been given the vaguest description of the white matter changes from the scan.
Some degree of white matter change is to be expected with age we also see small distinct white spots within the white matter in people with depression, in patients with migraine, and I have seen one report of white spots being found in military personnel returning after stressful duties in Iraq.

Elizabeth is suffering with headaches just on the left side

There is no confirmed evidence about what these spots mean.

Another more widespread type of white matter change can occur due to a condition called cerebral small vessel disease.

This is damage to the smallest blood vessels from thickening of the vessel walls and cholesterol deposits.

The most common risk factor for this is having high blood pressure. Between 11 and 21 per cent of people in their 60s, and 94 per cent of people at age 82, will have some degree of cerebral small vessel disease.

The damage can progress to senile dementia, but this is not inevitable.

Small vessel disease can be present without any evidence of cognitive impairment, but it may, in the continued presence of raised blood pressure, progress over months and years to mild cognitive impairment or, later, to dementia.

The essential point for you is to be absolutely certain that your blood pressure is normal - and if it is not, then you must receive effective treatment to control it.

Smoking, heavy alcohol intake, diabetes, and obesity also increase the risk of small vessel disease.
A healthy diet and regular physical exercise are known to be beneficial - so do keep as active as you can: so keep up the gardening!

The stethoscope allows us to listen to the heart, the lungs and the carotid arteries in the neck

Sopko is not alone. Experts believe a majority of people with COVID-19 will experience “some measurable olfactory disfunction.”

“It is more common with COVID than with any other viral disorders. It is often the case that many people will lose their sense of smell and they'll say their sense of taste,” Pam Dalton, a faculty member at the Monell Chemical Senses Center in Philadelphia, told TODAY. “But, generally, it’s the flavor that gets diminished when you lose your ability to smell.”

Anyone who has had a bad cold knows that it can affect smell and taste. But the reasons why differ. When people lose their ability to smell when grappling with a sinus infection or cold, it’s often because the mucous prevents the nose from doing its job.


Health & Wellness Some COVID-19 survivors experience prolonged loss of senses. Will they come back?

“Some of that with the common cold is really due to nasal congestion,” Dalton explained. “The molecule simply can’t make it into the nose where the receptor is.”

But what happens with COVID-19 appears different: Experts believe that it targets the neurons responsible for smell.

“Infection and loss of function of the supporting cells leads to loss of the olfactory sensory neurons,” Dr. Claire Hopkins, a professor of rhinology at King’s College London, told TODAY via email. “Fortunately, these have a unique capacity in the nervous system to regenerate — and most patients will still recover but it can take months for this to happen.”

Latest Updates

The most immediate effects may be nutritional. People with anosmia may continue to perceive basic tastes — salty, sour, sweet, bitter and umami. But taste buds are relatively crude preceptors. Smell adds complexity to the perception of flavor via hundreds of odor receptors signaling the brain.

Many people who can’t smell will lose their appetites, putting them at risk of nutritional deficits and unintended weight loss. Kara VanGuilder, who lives in Brookline, Mass., said she has lost 20 pounds since March, when her sense of smell vanished.

“I call it the Covid diet,” said Ms. VanGuilder, 26, who works in medical administration. “There no point in indulging in brownies if I can’t really taste the brownie.”

But while she jokes about it, she added, the loss has been distressing: “For a few months, every day almost, I would cry at the end of the day.”

Smells also serve as a primal alarm system alerting humans to dangers in our environment, like fires or gas leaks. A diminished sense of smell in old age is one reason older individuals are more prone to accidents, like fires caused by leaving burning food on the stove.

Michele Miller, of Bayside, N.Y., was infected with the coronavirus in March and hasn’t smelled anything since then. Recently, her husband and daughter rushed her out of their house, saying the kitchen was filling with gas.

She had no idea. “It’s one thing not to smell and taste, but this is survival,” Ms. Miller said.

Humans constantly scan their environments for smells that signal changes and potential harms, though the process is not always conscious, said Dr. Dalton, of the Monell Chemical Senses Center.

Smell alerts the brain to the mundane, like dirty clothes, and the risky, like spoiled food. Without this form of detection, “people get anxious about things,” Dr. Dalton said.

Even worse, some Covid-19 survivors are tormented by phantom odors that are unpleasant and often noxious, like the smells of burning plastic, ammonia or feces, a distortion called parosmia.

Eric Reynolds, a 51-year-old probation officer in Santa Maria, Calif., lost his sense of smell when he contracted Covid-19 in April. Now, he said, he often perceives foul odors that he knows don’t exist. Diet drinks taste like dirt soap and laundry detergent smell like stagnant water or ammonia.

“I can’t do dishes, it makes me gag,” Mr. Reynolds said. He’s also haunted by phantom smells of corn chips and a scent he calls “old lady perfume smell.”

It’s not unusual for patients like him to develop food aversions related to their distorted perceptions, said Dr. Evan R. Reiter, medical director of the smell and taste center at Virginia Commonwealth University, who has been tracking the recovery of some 2,000 Covid-19 patients who lost their sense of smell.

One of his patients is recovering, but “now that it’s coming back, she’s saying that everything or virtually everything that she eats will give her a gasoline taste or smell,” Dr. Reiter said.

The derangement of smell may be part of the recovery process, as receptors in the nose struggle to reawaken, sending signals to the brain that misfire or are misread, Dr. Reiter said.

After loss of smell, “different populations or subtypes of receptors may be impacted to different degrees, so the signals your brain is used to getting when you eat steak will be distorted and may trick your brain into thinking you’re eating dog poop or something else that’s not palatable.”

Patients desperate for answers and treatment have tried therapies like smell training: sniffing essential oils or sachets with a variety of odors — such as lavender, eucalyptus, cinnamon and chocolate — several times a day in an effort to coax back the sense of smell. A recent study of 153 patients in Germany found the training could be moderately helpful in those who had lower olfactory functioning and in those with parosmia.

Dr. Alfred Iloreta, an otolaryngologist at Mount Sinai Hospital in New York, has begun a clinical trial to see whether taking fish oil helps restore the sense of smell. The omega-3 fatty acids found in fish oil may protect nerve cells from further damage or help regenerate nerve growth, he suggested.

“If you have no smell or taste, you have a hard time eating anything, and that’s a massive quality of life issue,” Dr. Iloreta said. “My patients, and the people I know who have lost their smell, are completely wrecked by it.”

Mr. Reynolds feels the loss most acutely when he goes to the beach near his home to walk. He no longer smells the ocean or salt air.

“My mind knows what it smells like,” he said. “And when I get there, it’s not there.”

How good is your sense of smell?

An acute loss of smell is one of the most common symptoms of COVID-19, but for two decades it has been linked to other maladies among them Parkinson's disease and dementia. Now, a poor sense of smell may signify a higher risk of pneumonia in older adults, says a team of Michigan State University researchers.

"About a quarter of adults 65 years or older have a poor sense of smell," said Honglei Chen, a professor in the Department of Epidemiology and Biostatistics within MSU's College of Human Medicine. "Unlike vision or hearing impairment, this sensory deficit has been largely neglected more than two-thirds of people with a poor sense of smell do not know they have it."

In a first-of-its-kind study, Chen and his team found a possible link between poor sense of smell and a higher risk of pneumonia hospitalization. They analyzed 13 years of health data from 2,494 older adults, ages 71-82, from metropolitan areas of Pittsburgh, Pennsylvania, and Memphis, Tennessee. This study aimed to examine whether a poor sense of smell in older adults is associated with a higher future risk of developing pneumonia.

Chen's research was recently published in the journal The Lancet Healthy Longevity. The participants were given a Brief Smell Identification Test, or B-SIT, using common smells such as lemons and gasoline to determine if their sense of smell was good, moderate or poor. Then, the participants were monitored for the next 13 years using clinical exams and follow-up phone calls to identify hospitalization due to pneumonia.

The researchers found that compared with participants who had a good sense of smell, participants with a poor sense of smell were about 50% more likely to be hospitalized with pneumonia at any time point during the 13-year follow-up. Among participants (with a poor sense of smell) who never had had pneumonia before, the risk of having the first-ever pneumonia was about 40% higher.

"To our knowledge, this study provides the first epidemiological evidence that poor olfaction (sense of smell) is associated with a long-term higher risk of pneumonia in older adults," said Yaqun Yuan, a postdoctoral fellow in Chen's research group.

This study provides novel evidence that a poor sense of smell may have broader health implications beyond its connections to Parkinson's disease and dementia.

"This is just an example how little we know about this common sensory deficit," Chen said. "Either as a risk factor or as a marker, poor sense of smell in older adults may herald multiple chronic diseases beyond what we have known about. We need to think out of the box."