Phantosmia: A Complete Guide to Smell Hallucinations

Phantosmia is when one senses a strong odor that isn’t there and is also referred to as an olfactory hallucination. Phantosmia can be brought on by a variety of factors but can easily be diagnosed and treated. This phenomenon affects under 10% of the population, but could your nose be deceiving you? Read ahead to find out more if you or someone you know has it or if it’s a smelly coincidence.


What is Phantosmia?

Phantosmia is a dysfunction within the olfactory senses, our sense of smell, that registers odors that are non-existent in the air and is typically reported as a foul smell. This faulty smell can either occur in one or both nostrils and the condition is commonly temporary. Symptoms differentiate in every person. It is not life threatening though if continued and disruptive to your daily life, seeing your general physician is recommended.

The way our sense of smell is organized is through nasal membranes, in the nose, that contain olfactory sensory neurons that aid in detecting smells, often referred to as “front door” senses. The sensory neurons are connected to the brain and discern odor molecules that are sent directly there to identify the smell.

This false detection of smell affects our sense of taste too as they are guided by described “back door” senses.  Different from “front door” senses, back door senses connect to the back of the throat into the nasal cavity. When eating, odor molecules are released and continue to the throat where the odor molecules are released and pushed into the nasal cavity. This impacts the taste (gustatory system) and smell emitted from the food you eat and attribute to phantosmic-like experiences.

Causes of Phantosmia

Its causes may be brought on by upper respiratory infections, head injury or concussion, temporal lobe lesions, or in rare cases brain tumors. Nasal infections are the most common of causes of phantosmia due to the sinuses being blocked and barriers within the air passageway for proper nasal respiration to be fulfilled. Nasal polyps are a typical cause of phantosmia also. Nasal polyps are tissue growths in the nasal cavity that may block air passageways and affect the sinuses and is experienced as a stuffy nasal feeling. Some environmental causes include dental issues, smoking, radiation and chemical exposure. Many who suffer from epilepsy report experiences of phantosmia either directly before or after a seizure episode.

Neurological conditions like Parkinson’s disease, head injuries, strokes, and tumors may also cause phantosmia. This is due to irregular neuron firing which is recommended to see a physician if you believe may be the case.

Smell disorders may also be a side effect of emotional and mental disorders like substance withdrawal, depression, or bipolar disorder. Neurons may transmit incorrect signals or a malfunction of olfactory neurons may be the underlying reason in this case, similar to neurological expressions of phantosmia.

Development of Phantosmia

Its development can occur gradually over days to even several years. The sensation of phantosmia can initially last a few minutes but may gradually increase in length of time over weeks, months, and years. If you have had repeated nasal and sinus infections, your risk may be increased. If it is caused by an illness or sinus infection, it will usually resolve itself. A quarter of those who report having phantosmia in one nostril usually develops it in the other nostril over a course of months or years.

Those who suffer from neuroblastoma are proved to be susceptible to phantosmia. Neuroblastoma is a malignant and rare form of cancer in the olfactory nerve. As cancer develops, it can become aggressive and present itself in ethmoid sinuses in the cribriform plate of the brain. By having a biopsy done, one may be treated with radiation or chemotherapy but may affect the olfactory system again resulting in further phantosmia.

Comorbidity and Phantosmia

Pregnancy and Parkinson’s disease are the most common co-occurring states that phantosmia is expressed. Studies have shown that 76% of pregnant women have experienced significant changes in perceptions of gustation and olfaction. Sensitivity to smell and taste is a common side effect of pregnancy due to the multitude of changes taking place in the woman’s body. Diet adjustment was seen to be the most useful in these changes to taste and smell.

For Parkinson’s disease, it was believed that phantosmia usually occurs chronologically later into the disease. Recent studies have shown that phantosmia occurs earlier in the development of Parkinson’s disease. This is now seen as a biomarker for the disease and can develop and be experienced several years before motor symptoms. One study found that up to 72% of those with Parkinson’s are not aware of personal deficits with olfactory disorders. Though not all that suffer from Parkinson’s experience phantosmia, it is important to be aware of phantosmia or other olfactory and sense of taste disorders to consider as a symptom.

Diagnosis of Phantosmia

It can be difficult due to the variety of reasons in causes or development. The physician will need to identify if it is an issue in the olfactory (smell) or gustatory (taste) system. If it is indeed an olfactory issue, there are forms of olfactory disorders listed that may suit the case in question.

Examples of other olfactory disorders include anosmia, dysosmia, hyperosmia, parosmia, and troposmia. These -osmias’ are variations of olfactory disorders relating to duration, onset, and occurrence.

The patient needs to describe the experience they are having odor-wise and what kind of smell is being emitted to them. This step in the diagnosis process may be difficult due to the possibility of the phantosmia leaving the system entirely because of its temporary nature. The following step is to address the patients’ medical history to assess any possible concussions, brain injuries, trauma, previous respiratory infections.

Phantosmia Treatment

Because it has a multitude of causes and factors into diagnoses, the treatment can be difficult, though there are common measures you can take to help you with those smelly symptoms. Always be sure to talk to your doctor about other options suited the best for you!

Nasal Sprays

The most common treatment for phantosmia is a nasal saline solution. This acts as a clearing of sinuses that can be blocked and assists air passageways to open and enter the olfactory senses. Oxymetazoline HCI is the most common and provides a longer term of relief.

Venlafaxine (Antidepressant)

This antidepressant is a serotonin-norepinephrine reuptake inhibitor. Those who have to use Venlafaxine for phantosmia have found relief in that over time the sensations disappear. This is supported in cases of medications for seizures as well, as they both act on the central and peripheral neurons.

If this sounds like you or someone you may know, talk to your physician! If this was helpful, be sure to comment down below!

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