What’s That Smell? What You Need to Know About Hyperosmia

Overview of Hyperosmia

Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications.

Updated on February 03, 2022

John Carew, MD, is board-certified in otolaryngology and is an adjunct assistant professor at New York University Medical Center.

Table of Contents
Table of Contents

Hyperosmia is an increased sensitivity to smell, and it is often accompanied by unpleasant symptoms. It may occur intermittently, particularly when it happens in association with certain medical conditions, such as migraine or upper respiratory infections.

Less often, hyperosmia can also be genetic, usually manifesting as persistently heightened smell sensitivity. Most of the time, it isn’t necessary to seek treatment for hyperosmia. But if the symptoms are becoming bothersome for you, there are some treatments and coping strategies you can adopt to alleviate the negative effects.

Hyperosmia Symptoms

Interestingly, with hyperosmia, your sense of smell may be intensified for some odors but less sensitive to others. You can have a disagreeable reaction, a neutral response, or you may even enjoy your amplified sense of smell. With hyperosmia, you are likely to have all three of the following types of reactions at one point.

Unpleasant Reactions

Hyperosmia may make certain smells particularly distasteful. You can feel nauseated or disgusted, and the odors can even trigger migraines or allergies.

There is a strong relationship between hyperosmia and osmophobia (aversion to certain smells). Either of these conditions can lead to the other.

Despite the name, osmophobia is not necessarily a fear of bad smells. Instead, it is usually an extreme aversion and disgust. In some cases, osmophobia can progress to produce a fear of certain offending smells if you become anxious about the effects that certain odors may have on you.

Hereditary Hyperosmia and Super Smellers

The increased odor sensitivity of hyperosmia is not always negative. Hyperosmia allows you to detect and distinguish smells that do not necessarily provoke a disagreeable reaction, particularly if your hyperosmia is due to a genetic predisposition rather than a medical condition.

Some people who have genetic hyperosmia are described as “super smellers” and are able to detect and identify subtle aromas with great precision. This above-average aptitude may allow some super smellers to identify diseases (most notably Parkinson’s disease) before they can be diagnosed clinically.

If you have had hyperosmia since you were born, you might not even realize that you have the condition because your acute sense of smell feels normal for you.

Some practical advantages of hyperosmia include detecting the location of a dangerous smell, like smoke or a chemical leak, or noticing that food is rotting.

Obesity

On the other hand, it has been noted that heightened smell sensitivity can be associated with obesity. This is likely because your appetite and enjoyment of food rely not only on taste, but on smell as well.

If you have noticed that food tends to smell more appetizing to you than to other people, you should discuss this with your healthcare provider (if you are also overweight) because it could affect your long-term health.

Causes

Some people naturally have a heightened sensitivity to smell all the time. This is believed to be genetic, and it has been linked with the SCN9A gene, which codes for sodium channels (a component of nerve cells) in the body. This may not be the only gene associated with hyperosmia, however, and the condition could be related to several genes.

You may also have episodes of hyperosmia at certain times, such as during pregnancy or when your allergies are acting up. Some medical conditions can make you develop lasting hyperosmia, either suddenly or gradually.

Common Causes

Several conditions are often characterized by hyperosmia and osmophobia. These conditions are typically episodic, like epilepsy, migraine, and allergies. Other conditions, such as toxin exposure, are not common and may be difficult to pinpoint.

Pregnancy: An increased sensitivity to smells is commonly reported in the first and second trimester of pregnancy. Hyperosmia can trigger nausea and vomiting, and it has been associated with hyperemesis gravidarum (excessive vomiting during pregnancy typically requiring medical treatment and intravenous or IV fluids).

Migraines: Heightened sensitivity as well as repulsion by certain odors is very common in the pre-migraine premonitory stage, as well as during the peak of a migraine. This tends to diminish after a migraine subsides, but people with recurrent migraines tend to have increased sensitivity to smells even during migraine-free times.

Allergies: Nasal congestion often occurs with allergies that affect the upper respiratory system. This can interfere with the detection of smell. Ironically, allergies are also associated with hyperosmia (during as well as in between allergy attacks). This is thought to be related to alterations in superficial nerve sensors in nasal passageways.

Upper respiratory infection: A sinus infection can give you a stuffy nose. While your smell detection can be obscured, you can develop hyperosmia to some smells, too.

Epilepsy: An exaggerated sense of smell can occur as a pre-seizure aura. In rare instances, hyperosmia can also be present during or after a seizure.

If you have epilepsy-associated hyperosmia, you might smell things that others don’t smell at all—either because the odor is subtle or because it may not be present at all.

If the odor is not present at all, you may not necessarily be experiencing true hyperosmia, but your symptoms may be described this way.

Toxin exposure: There are numerous reports of hyperosmia beginning after exposure to toxins such as lead or mercury.   Hyperosmia may be just one of many consequences of chemical toxicity. Sometimes, this effect becomes obvious after several people who were exposed to the same chemical are diagnosed with similar effects.

You could be exposed to neurotoxic chemicals in an industrial setting or through the use of medications or cosmetics.

Neurological and Immune Conditions

Hyperosmia has been reported in association with a number of conditions, including vitamin B12 deficiency, Lyme disease, lupus, multiple sclerosis (MS), and Tourette’s syndrome.

An alteration in smell sensation is not the predominant or most common symptom of any of these conditions, but hyperosmia has been reported frequently enough that it is among the well-recognized effects.

Rare Causes

Neurological conditions, particularly Alzheimer’s disease, Parkinson’s disease, and stroke, are frequently associated with hyposmia, which is a decreased sensitivity to smell.

While hyposmia is usually the cause of decreased appetite and weight loss, hyperosmia often accompanies the hyposmia. This is because there is an alteration of the whole olfactory (smelling) system, not just a decrease in function.

Furthermore, it is usually the unpleasant smells that are most noticeable, although this could be simply because people are more likely to notice and react to unpleasant smells than to pleasant smells.

Physiological Causes

Odor detection and identification are controlled by the olfactory nerve, also described as cranial nerve one or the first cranial nerve. Smell receptors on the surface of the nasal passages activate the olfactory nerve, which sends messages to the brain’s cerebral cortex, allowing you to recognize and react to those odors.

Dysfunction of your sense of smell can occur due to problems with the receptors, the nerve, or the areas of the cerebral cortex (hippocampus, orbitofrontal cortex, and insula) that integrate those messages.

Each cause of hyperosmia is due to a deficit somewhere along this pathway. For example, hyperosmia in epilepsy is caused by altered activity in the cerebral cortex, while hyperosmia associated with an upper respiratory infection is caused by a problem with superficial odor detection on the nasal passages.

Super smellers have been found to have an enlarged hippocampus, which is an area of the brain typically associated with emotions and memory, and orbitofrontal cortex, where odors are consciously recognized.

Diagnosis

Hyperosmia is typically diagnosed based on your symptoms. It is not usually the only symptom of any medical condition. However, when you experience the symptoms of hyperosmia, it can be a clue that your underlying cause is acting up.

For example, if you are frequently repulsed by food before your migraines, this can be an indication that you should take your medication. If you are trying to get pregnant, you may feel disgusted by the odor of the cafeteria at work even before you have a positive pregnancy test.

Of course, try to observe this symptom without necessarily diagnosing yourself. Pending an official test, you won’t know exactly what is causing your enhanced ability to smell.

Diagnostic Testing

Your healthcare provider may administer a diagnostic test to verify that you have hyperosmia. The University of Pennsylvania Smell Identification Test (UPSIT) is a 40-item test used to diagnose smell defects caused by diseases such as Alzheimer’s disease and Parkinson’s disease.

Your score on this test can be compared to the average to assess whether you have a heightened sensitivity to odors.

Differential Diagnosis

There are a few conditions that can seem like hyperosmia. You may benefit from treatment if you are experiencing these similar conditions.

Olfactory reference syndrome (ORS) is a rare condition in which people are paranoid about their own body smell. It is characterized by unusual and unwarranted apprehension about your own body odor.

This could stem from a life situation, such as experiencing or witnessing embarrassment or humiliation about body odor. It could also be due to true body odor that is too mild for others to detect, but that you can detect because of your own heightened sensitivity to smell.

Another similar condition, parosmia, is an altered perception of smell, in which some odors are consistently detected incorrectly. This disorder is associated with a reduced volume of the hippocampus and other areas of the brain that control the sense of smell.

There are all types of sensory hallucinations, which are altered perceptions or perceptions of things that are not there. An olfactory hallucination is a fixed belief that you smell some type of odor that doesn’t exist.

Hallucinations are a sign of psychosis, which is a very serious disorder that requires treatment with prescription antipsychotics. Psychosis can occur due to a disease of the brain, or it can be a medication side effect.

Treatment

Hyperosmia is treatable, to a degree. It’s likely that you may not want medication for your hyperosmia.

If you have allergies, migraines, or if you are pregnant, your other symptoms may be more concerning for you. If you have lupus, MS, or vitamin B12 deficiency, treatment of your underlying disease is the best way to minimize your hyperosmia.

However, if the hyperosmia is interfering with your quality of life, there are a few medical approaches you can take to alleviate this problem.

Antiemetics

Over-the-counter (OTC) and prescription medication can help control nausea and vomiting if this is the most distressing aspect of your hyperosmia. Most of the time, OTC medications like Dramamine (dimenhydrinate), Bonine (meclizine), and Benadryl (diphenhydramine) are enough to control your nausea and vomiting.

Be sure to check with your healthcare provider or pharmacist before using antiemetics because they might not be safe for you if you are pregnant or taking other medications. The most common prescription-strength antiemetics include Compazine (prochlorperazine), Reglan (metoclopramide), and Zofran (odansetron).

Nerve Ablation

In rare situations, hyperosmia can be such a severe problem that you may need surgery. This will decrease the function of the olfactory nerve so that the odors you smell will not prevent you from eating or cause you to eat so much that your health is at risk.

This option should be thoroughly discussed with your healthcare provider in order to determine if it’s the best treatment method for you.

Coping

If you have hyperosmia, there are a number of practical steps you can take to manage your condition. You may need to wear a mask if you work in a setting with strong odors. You can also try to disguise offending smells by chewing gum or sucking on candy or a mint.

Some people can’t stand to be around certain odors at all and might not be able to work in a hospital or a factory that contains distress-inducing odors. If that is your situation, you may need to make a change to your work or home environment to eliminate your exposure to the distressing odors.

A Word From Verywell

Hyperosmia is fairly common, but it is rarely a major problem. If you notice this as a recurring symptom that precedes an impending health problem, such as an MS exacerbation, a migraine, an allergy attack, or a seizure, you may be able to take medication in time to minimize the effects of an attack.

For the most part, hyperosmia is actually helpful in detecting dangerous situations, such as a fire or spoiled food. Some experts believe hyperosmia is a beneficial trait rather than a problem because it can help prevent serious injuries or illnesses.

Nevertheless, if your hyperosmia is interfering with your life, be sure to talk to your healthcare provider and get treated so that aromas won’t limit your ability to be around other people, eat, work, or enjoy life.

Frequently Asked Questions

How common is hyperosmia?

Not very. In studies, the condition frequently is described as extremely rare. Except during pregnancy or as a result of certain conditions, such as migraines, hyperosmia often is regarded as psychosomatic—meaning it does not have a physical origin.

What causes sense of smell to be heightened during pregnancy?

The exact physiology isn’t known but there are theories, One is that increased levels the hormone human chorionic gonadotropin (hCG) may play a role. Another is that people may be more aware of odors during pregnancy and react more strongly to them, rather than truly sensing them more acutely.

Can I improve my sense of smell?

• Phenyl ethyl alcohol (rose)
• Eucalyptol (eucalyptus)
• Citronellal (lemon)
• Resinous (cloves)

Twice a day, spend five minutes exposing your nose to each smell. Sniff one for 10 seconds, wait 10 seconds, and sniff the next.

18 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

1. Rocha-Filho P, Marques KS, Santos Torres RC, Ribas Leal KN. Migraine, osmophobia, and anxiety. Pain Medicine. 2016(17);4:776–780. doi:10.1093/pm/pnv071
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7. Cleveland Clinic. What’s that smell? What you need to know about hyperosmia.
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9. Wehling E, Naess H, Wollschlaeger D, et al. Olfactory dysfunction in chronic stroke patients. BMC Neurol. 2015;15:199. doi:10.1186/s12883-015-0463-5
10. Good KP, Sullivan RL. Olfactory function in psychotic disorders: Insights from neuroimaging studies. World J Psychiatry. 2015;5(2):210-221. doi:10.5498/wjp.v5.i2.210
11. Devanand DP, Lee S, Luchsinger JA, et al. Intact global cognitive and olfactory ability predicts lack of transition to dementia. Alzheimers Dement. 2019;16(2):326–334. doi:10.1016/j.jalz.2019.08.200
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14. Kar SK, Garg K, Tripathi A. Olfactory hallucinations in schizophrenia: does it carry any meaning?Int J Nutr Pharmacol Neurol Dis. 2016;6(3):136-138. doi:10.4103/2231-0738.184597
15. American Academy of Family Physicians. Antiemetic medicines: OTC relief for nausea and vomiting.
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17. Merck Manual Consumer Version. Overview of Smell and Taste Disorders.
18. Whitcroft KL, Hummel T. Olfactory dysfunction in COVID-19: Diagnosis and management. JAMA. 2020;323(24):2512-2514. doi:10.1001/jama.2020.8391

Additional Reading

• Bitter T, Siegert F, Gudziol H, et al. Gray matter alterations in parosmia. Neuroscience. 2011 Mar 17;177:177-182. doi:10.1016/j.neuroscience.2011.01.016
• Haehner A, Hummel T, Heinritz W, et al. Mutation in Nav 1.7 causes high olfactory sensitivity. Eur J Pain. 2018;22(10):1767-1773. doi:10.1002/ejp.1272
• Kronenbuerger M, Belenghi P, Ilgner J, Freiherr J, Hummel T, Neuner I. Olfactory functioning in adults with Tourette syndrome. PLOS ONE. 2018;13(6):e0197598. doi:10.1371/journal.pone.0197598
• Marmura MJ, Monteith TS, Anjum W, Doty RL, Hegarty SE, Keith SW. Olfactory function in migraine both during and between attacks. Cephalalgia. 2014;34(12):977-985. doi:10.1177/0333102414527014

By Heidi Moawad, MD
Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications.

What’s That Smell? What You Need to Know About Hyperosmia

Whether it’s the smell of cookies baking or Fido’s … ahem … gas, smells have a way of seizing our attention. But when subtle odors interfere with daily living, you may have a condition called hyperosmia.

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“Hyperosmia is a heightened or increased sense of smell,” explains ENT (ear, nose and throat) specialist and rhinologist Raj Sindwani, MD. People can experience it all the time or occasionally. And while hyperosmia doesn’t always require treatment, it can signal an underlying health issue that does. Dr. Sindwani shares what you need to know about this unique and uncommon smell disorder.

What causes hyperosmia?

Hyperosmia is relatively rare, and doctors usually don’t know why someone develops it. But there’s a seemingly endless list of things that may be to blame, including:

• Pregnancy.
• Epilepsy.
• Addison’s disease (when your adrenal glands don’t make enough hormones).
• Psychiatric conditions.
• Lyme disease.
• Multiple sclerosis.

“Other factors can also disturb our sense of smell, including exposure to toxins, such as lead or mercury. Allergies, polyps and tumors can also affect smell. So can things like diabetes and nutritional deficiencies. It’s all over the map when it comes to smell disturbances,” notes Dr. Sindwani.

While smell disorders don’t run in families, an underlying cause might. “We don’t know what causes smell disorders — so there’s no real genetic link that we’re aware of. For example, cystic fibrosis can run in families and affect smell. But smell disorders on their own generally do not.”

Sensitive to smells? How to know if it’s hyperosmia

It’s complicated. Because so many things may cause hyperosmia, symptoms can include anything and everything. But Dr. Sindwani recommends seeing a doctor if:

• The hypersensitivity to smells is persistent.
• You feel like there’s a change in how you perceive odors.

How is hyperosmia diagnosed?

“A doctor can rule out a treatable causes for your sensitivity to smell by reviewing your health history and doing a physical exam,” says Dr. Sindwani. “A nasal endoscopy is the gold standard test to rule out anything physical going on in your nose like a mass, polyps or infection.”

During this minor procedure (which is performed with you awake and sitting in an exam chair – don’t worry it doesn’t hurt!), your doctor:

1. Places a camera onto the end of a tiny rigid or flexible telescope.
2. Guides the scope gently into your nose to look around, while the camera transmits images to a TV screen.
3. Examines the images to see if there are any physical issues that would affect your ability to smell.

“With this type of endoscopy, we can actually see the area where the smell receptors live high up in the nasal cavity,” explains Dr. Sindwani.

If your nose gets the “all clear,” your doctor may do a “scratch and sniff” smell test. If that points to an increased sense of smell, hyperosmia is usually the diagnosis.

Smell and taste are also closely linked. (Ever smell something so strong you could taste it?) For that reason, a smell disorder can initially seem like a taste problem. “Often, people come in and say, ‘Things don’t taste right to me,’ when over time, we learn it’s a smell problem. You can have one, the other or both of those things in play.”

How to turn the dial down on your nose

If you suspect you have hyperosmia or another smelling issue, Dr. Sindwani says a good first step is to see an ENT specialist. The specialist can rule out any physical causes for smell problems, such as tumors, polyps or infection. Sometimes imaging tests (like a CT or MRI scan) can also be helpful in looking for underlying issues.

“Beyond that, hyperosmia should be managed depending on what the underlying issue is. Migraines might be treated by your internist or neurologist, for example. If you have a brain issue, such as epilepsy, multiple sclerosis, Alzheimer’s disease or Parkinson’s disease, that might be treated by a neurologist or other type of doctor as well.”

But determining a treatment plan can be challenging since causes are hard to pinpoint. In those cases,doctors can recommend supportive treatment measures, such as:

• Saline washes or sprays to keep the nose healthy and moist.
• Medications to help with any nausea or vomiting induced by your extreme sensitivity to smells.
• Masks to block strong odors.
• Gum or candy to disguise cringe-worthy smells.