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'Phantosmia' is the medical term for an imaginary odour (phantom smell).
It is also known as an "olfactory hallucination".
The smell is unique to the person and is usually unpleasant, spoiling the taste of any food or drink consumed. It can be in one or both nostrils.
Most phantom smells go away in time and are not caused by anything serious. But if the problem persists and you're worried, see your doctor.
When something gives off a smell, it means tiny molecules have evaporated from its surface and reached your nose.
High up inside your nose is tissue containing specialised nerve cells, called olfactory sensory neurons, which connect directly to your brain.
These nerve cells have receptors that detect the microscopic odour molecules and send electrical signals to the brain. The brain receives these signals and identifies the smell.
There are two ways smells can reach the olfactory sensory neurons:
There are a wide range of possible causes of phantosmia, which include:
Less commonly, the cause of phantosmia is either nerve cells sending abnormal smell signals to the brain, or a problem with the brain itself.
This may be the result of:
Your doctor will want to know if the problem is definitely with your sense of smell, and not with your sense of taste (it's easy to confuse these).
They will also want to determine whether the smell is perceived, as in phantosmia, or actually real – you might be giving off and detecting a body odour, for example.
You'll have a head and neck examination, to see if there is any obvious problem such as something in your nasal passages. The doctor will want to know if the smell transmits through one nostril or both.
You may be referred to an ear, nose and throat specialist for further tests, which may include:
Some people with phantosmia will find that the smell gradually fades over a few months, and no treatment is needed.
If it is caused by an illness such as sinusitis, it should go when you recover from the illness.
Otherwise, if it persists, the following treatments may be tried:
You must always weigh up the benefits of these treatments with the possible side effects – speak to your doctor about this.
Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.