Overview of Hyperosmia

A strong sense of smell has pros and cons

In This Article

Pregnant woman smelling orange with her eyes closed

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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 your hyperosmia. But if the symptoms are becoming bothersome for you, there are some treatments and coping strategies that you can adapt to alleviate the negative effects. 

Symptoms 

Interestingly, with hyperosmia, your sense of smell may be intensified for some odors and it can be less sensitive to others. You can have a disagreeable reaction, a neutral response, and 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 your 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. If you catch yourself frequently noticing and commenting about scents that most other people don’t notice, you might begin to suspect that your sense of smell is unusually sharp. Or you may be able to identify the difference between various smells with greater accuracy than most people you know.

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 doctor (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 

There are several conditions that 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 to certain odors 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 feeling tends to diminish after a migraine subsides, but people who have 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 the superficial nerve sensors located in the 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 Cause 

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 doctor 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)

This 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 indeed 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.

Parosmia

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.

Hallucinations

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. This is 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 doctor or pharmacist before using them 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) and Reglan (metoclopramide).

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 doctor 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 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 doctor and get treated so that aromas won’t limit your ability to be around other people, eat, work, or enjoy life. 

 

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