It’s a strange thing to suddenly smell something that no one else can. For most people, the idea of experiencing a phantom smell may sound a little unsettling, but for some, it’s a daily reality. Welcome to the world of phantosmia, a condition where individuals perceive smells that aren’t actually there. Known as "olfactory hallucinations," phantosmia can turn a simple breath of fresh air into a confusing, sometimes overwhelming, experience. But what causes this curious phenomenon, and how can we make sense of it?

What is phantosmia?¹

Imagine sitting at your desk, working through the afternoon, when suddenly, an overpowering scent of smoke fills the air. But you’re not near any fire. No one else around you seems to notice anything. What could be going on?

Phantosmia occurs when the brain detects a smell that doesn't exist in the environment. It’s as if the brain is creating an olfactory experience out of nothing. For those who suffer from it, it can range from mild annoyances to a distressing daily occurrence. The smells are often unpleasant—burnt toast, rotting food, or even chemicals—and sometimes they linger for hours, making it hard to focus on anything else.

This condition is surprisingly common. Research suggests that around 1-2% of the population has experienced phantosmia at some point in their lives. Yet, few are aware of the term or understand why it happens. To grasp the full picture, we need to take a closer look at the senses and the brain’s role in interpreting smells.

The science behind the smell

To understand phantosmia, we first need to explore how we usually smell things. Here’s how it works:

• When we inhale, molecules from objects around us enter our nostrils and bind to receptors in the nose.
• These receptors send signals to the brain, which processes the information, allowing us to identify the scent.

It’s an intricate dance between the nose and the brain. However, phantosmia disrupts this process. Instead of reacting to external stimuli, the brain triggers the sensation of smell without any actual smell molecules present. Essentially, it’s as though the brain is malfunctioning, sending false signals to the olfactory system. But why would it do this?

Causes of phantosmia²

While the exact cause of phantosmia is not always clear, several factors can contribute to the condition. Some of the most common triggers include:

• Damage to the olfactory system: Often following a viral infection (such as a cold or flu) that inflames the sinuses and disrupts normal smell function.
• Head injury: Trauma to areas of the brain that process smells.
• Neurological disorders: Conditions like Parkinson’s disease, Alzheimer’s, or epilepsy can cause olfactory hallucinations.
• Mental health issues: Stress, anxiety, or depression can sometimes trigger the perception of phantom smells.
• Brain or nasal tumours: Although rare, growths in the brain or nasal passages may also cause phantosmia.

Interestingly, phantosmia has also been noted as a potential early warning sign for neurological diseases. Research suggests that olfactory dysfunction, including conditions like phantosmia, can sometimes precede other symptoms of disorders like Alzheimer's or Parkinson’s. In some cases, people may experience a distorted sense of smell years before the full onset of these diseases.

Managing phantosmia³

While there is no universal cure for phantosmia, treatments can help manage the symptoms. Here are some common strategies:

	Medications If phantosmia is related to sinus infections or nasal issues, doctors may prescribe antibiotics or corticosteroids. For neurological causes, medications targeting the brain may be recommended.
	Air purifiers or scented candles For many people, controlling the environment can help mask the phantom smells when they occur.
	Tracking symptoms Keeping a record of when phantom smells appear, and any potential triggers, can help doctors identify possible causes and solutions.

In some cases, phantosmia may resolve on its own. For others, coping strategies can help lessen the impact of phantom smells. Mark, for instance, learned to focus on controlling his environment. "It's a bit like managing a chronic condition," he says. "You get used to it and adapt, but it can still be unsettling."

The ongoing mystery

While much has been learned about phantosmia, there’s still a lot we don’t fully understand. Some key questions remain:

• Why do some people experience it for just a short time, while others deal with it for years?
• Why do certain smells appear more often than others?
• How can we definitively treat this mysterious condition?

What researchers do know is that the brain is a complex and sometimes unpredictable organ, and conditions like phantosmia are a reminder of how much is still left to discover about the senses and our perception of reality. The future of treatment is bright, however, with growing interest in the neurological and psychological factors that contribute to olfactory hallucinations. For those who experience phantosmia, the hope is that one day the answers will be clearer, and the treatments more effective.

You’re not alone

Phantosmia is a strange and often unsettling condition, but it’s a fascinating reminder of the intricacies of our senses and the brain’s role in shaping our perception of the world. For those who experience it, understanding the causes and seeking appropriate treatments can help restore a sense of control. While it may remain something of a medical mystery, the increasing awareness of phantosmia is an important step toward unravelling the complex ways in which our minds and bodies interact. So, the next time you smell something strange that no one else can, remember—you’re not alone.

References

1. Gillette B, Reid JA, Shermetaro C. Phantosmia. StatPearls. Available at: https://www.ncbi.nlm.nih.gov/books/NBK585128/.
2. Phantosmia (Olfactory Hallucinations). Cleveland Clinic. Available at: https://my.clevelandclinic.org/health/diseases/24799-phantosmia.
3. Altundag A. Parosmia and Phantosmia: Managing Quality Disorders. Curr Otorhinolaryngol Rep. 2023;11(1):19-26.