Phantosmia, also known as an olfactory hallucination or phantom smell, is when a person smells something that isn’t actually there. It can be any kind of burning smell, like burnt toast or cigarette smoke, as well as a metallic, chemical, or rotting smell.
Causes of phantom smells can include problems with the nose, brain, or nervous system. It’s important to note that phantosmia can also be caused by psychological factors, such as stress, anxiety, and obsessive-compulsive disorder (OCD)—though these cases are less common.
No matter the cause, understanding what’s behind the phantom smells is the first step toward finding the right treatment and gaining relief from the discomfort they may cause.
What is phantosmia?
Phantosmia is the perception of an odor with an absence of its source—like an illusion of a smell. The condition falls under the umbrella of dysosmia, which refers to any disorder that affects the sense of smell.
“Phantom smells can be any type of smell,” says Dr. Patrick McGrath, Chief Clinical Officer at NOCD. “It doesn’t have to be an unpleasant smell whatsoever. This can be food-related, bodily odors, or a smell that could be offensive to people.”
This may happen in one or both nostrils, and depending on the severity and frequency, phantosmia can cause distress and anxiety. Depending on its cause, treatment of phantosmia can vary.
What causes phantosmia?
The biological mechanism behind phantom odor perception is believed to come from irregular signaling in the olfactory sensory neurons, which are responsible for detecting smells, or from overactive brain cells that create the sensation of smell even when no odor is present.
In most cases, phantom smells go away on their own and are caused by temporary factors such as sinus infections, allergies, or stress. However, sometimes experiencing specific phantom smells, like the smell of burnt toast, may be an indication of a more serious health condition.
Is smelling burnt toast a sign of a heart attack?
Smelling burnt toast is not a typical sign of having a heart attack. However, phantosmia may occur in people with various cardiovascular conditions.
A 2020 study found that people who experienced congestive heart failure or chest pain, were around three times more likely to experience phantom smells compared to those without heart conditions.
It’s important to note that while the study indicates a higher incidence of phantosmia in individuals with heart disease, phantom smells are still more commonly associated with neurological or sinus-related issues rather than heart conditions.
The misconception that burnt toast is a warning sign of a heart attack likely stems from the fact that some people report smelling unusual odors just before experiencing a stroke or seizure. This is very different from the actual symptoms and typical signs of a heart attack, which usually include chest pain, shortness of breath, dizziness, and nausea. If you think you are experiencing warning signs of a heart attack, regardless of whether or not you smell burnt toast, you should call 911 immediately.
Is smelling burning toast a sign of a stroke?
Although you may experience phantom smells before a stroke, it is not a typical or reliable sign of having a stroke.
Instead signs of a stroke include sudden symptoms like sudden numbness or weakness in the face, arm, or leg—especially on one side of the body. Additionally, people having a stroke may experience confusion, trouble speaking, or difficulty understanding speech. They may also have trouble seeing, walking, dizziness, loss of balance or coordination, and a severe headache with no known cause. If you experience any of these stroke symptoms, call 911 immediately.
Other medical conditions related to phantosmia
Other central causes of phantosmia may include:
- Nasal issues: Nasal polyps, tumors, chronic sinus infections, hay fever, and non-allergic rhinitis are among the most common causes of smell disorders like phantosmia.
- Infections and illnesses: Upper respiratory tract infections, such as sinusitis or the flu, colds, and allergies can affect the olfactory system and lead to phantosmia. In some cases, viral infections like COVID-19 have been linked to temporary loss or distortion of smell, which can sometimes result in phantom smells.
- Mental health disorders: In some cases, obsessive-compulsive disorder (OCD), may cause intrusive thoughts and sensations, including a sensation of smell, which might make you perceive odors that aren’t actually present. Likewise, neuropsychiatric disorders such as schizophrenia may cause phantom smells.
- Certain medications: Phantom odor perception can be a side effect of certain medications, including antidiabetic and antihyperlipidemic agents.
- Pregnancy: Some people may experience olfactory distortions like phantosmia or a heightened sense of smell during pregnancy. While the exact cause isn’t known, it’s a common complaint among pregnant people.
- Parkinson’s and Alzheimer’s: Some individuals with these conditions experience olfactory dysfunction, meaning they have trouble with their sense of smell.
- Brain conditions: Less common causes of phantosmia include head trauma, sensory seizures, and migraines.
Sometimes, phantom smells can be idiopathic, meaning they occur without an identifiable or known cause. In many cases, no clear medical condition or trigger is found, and the reason for the phantom odor remains unknown.
How does OCD lead to thinking you smell burnt toast?
With obsessive-compulsive disorder, the brain might become excessively focused on smells, even when no actual odor is present. This hyperfocus is often triggered by anxiety or by an increased sensitivity to sensory stimuli, which are common features of OCD. As a result, people with OCD may perceive unpleasant smells that others do not, leading to persistent and distressing smells that aren’t real.
A 2018 study found that people with OCD may be more sensitive to smells that trigger feelings of disgust, such as unpleasant smells, compared to those without OCD, which may exacerbate obsessions and compulsions.
In OCD, obsessions are recurrent and unwanted intrusive thoughts, urges, feelings, sensations, or images, that cause distress or anxiety. In the case of olfactory obsessions, these intrusive thoughts are centered around smells—often unpleasant or contamination-related odors. The brain becomes fixated on these imagined smells, which can trigger intense feelings of anxiety. Even though no actual odor is present, the person with OCD believes that they are smelling something foul or dangerous.
In response to these obsessions, someone with OCD will perform compulsions to relieve anxiety or distress. For someone with contamination OCD, a subtype of OCD that involves fears of getting sick or contaminating others, this might look like frequent handwashing or cleaning to eliminate the smell—even if no such smell is present.
For someone with harm OCD, phantosmia could be connected to a fear of fire or being burned. This may cause someone to become obsessed with the idea that they accidentally caused a fire, possibly because of a perceived smell of smoke. In response, they may engage in excessive checking, such as repeatedly inspecting appliances, looking for signs of fire or danger.
The cycle of OCD involving obsessive thinking and compulsive behavior can cause significant distress and interfere with daily life. As a result, if phantom smells are connected to OCD, exposure and response prevention (ERP) therapy is the first-line approach to treatment.
How to treat phantosmia
If you think you’re experiencing heart-attack or stroke-like symptoms, it’s important that you receive immediate medical help. If you think your phantosmia is connected to a neurological issue, it’s also important to follow-up with a healthcare provider as soon as possible. If phantom smells are not accompanied by other serious symptoms, it’s still a good idea to talk to a healthcare provider or a therapist if this issue does not go away.
If you’re experiencing phantosmia as a result of OCD, the best treatment option for you is ERP, a form of therapy created specifically to treat OCD. During ERP, you’ll work to confront your triggers and intrusive thoughts while resisting the urge to do compulsions to decrease anxiety and distress.
Working with an ERP therapist might look like identifying the specific triggers that provoke the obsessional thoughts around phantom smells. These could include situations, images, or scenarios where you might fear you will accidentally harm someone—such as causing a fire due to burning toast.
If you have a fear of leaving the stove on and causing a fire, you might repeatedly check the stove to reassure yourself that it’s turned off. In ERP, you would be encouraged to prevent yourself from compulsively checking the stove any time you get worried.
“ERP is designed to weaken the link between obsessions and compulsions so that people might have an obsession, but don’t do the compulsion. Therefore, they aren’t being ruled by OCD anymore,” McGrath says. “Recreating the burning toast smell might be helpful to teach you that you’re not in any danger.”
Bottom line
Phantom smells can make you feel confused, anxious, or distressed—especially if you can’t identify the source of the odor. Because the smell isn’t real, it can lead to feelings of uncertainty or even frustration, as you might question if your mind is playing tricks on you or if there is an underlying health issue causing the sensation.
However, it’s important to remember that while phantom smells can be unsettling, they are often temporary and are not always indicative of a serious health issue. If they do cause distress, a healthcare provider can help you find the underlying cause and appropriate treatment that follows. If you think your phantosmia is related to OCD, a therapist who specializes in ERP can help you break the cycle of obsessions and compulsions around phantom smells.