Types of smell and taste impairment
Here we describe the different types of smell and taste impairment and the medical terms used to describe them. You can read more about the causes of smell and taste impairment on our website here
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Types of smell impairment
- Anosmia is the medical term for the inability to smell. Strictly speaking anosmia refers to the complete absence of the sense of smell but is also used to describe a situation where a person’s sense of smell is reduced to the extent that it is not useful in daily life. Some people are born without a sense of smell – this is known as congenital anosmia. Others may lose their sense of smell later in life – this is known as acquired anosmia.
- Hyposmia is the medical term for a reduced ability to smell. The point at which hyposmia becomes anosmia and vice versa isn’t exactly clear, however, and there are many degrees of olfactory loss. Some people lose their sense of smell completely and suddenly, whilst for others the loss of smell occurs gradually over time, so that the person may not realise that it is deteriorating.
- Parosmia is the medical term for experiencing distortions of the sense of smell. Someone with parosmia may be able to detect odours, but the smell of certain things – or sometimes everything – is different and often unpleasant. These unpleasant smells are often described as being like chemicals, burning, faeces, rotting flesh or mould. For some people, they appear in response to specific odours and for others, they can be triggered by virtually any smell.
- Phantosmia is the medical term for smelling things that aren’t present. These are sometimes called olfactory hallucinations, or phantom smells, that appear in the absence of any odour. They can manifest as ‘normal’ smells – for example, being able to smell garlic when there is no garlic present – but they can also be unpleasant.
- Olfactory intoleranceis the medical term for a hypersensitivity to everyday odours, without odour distortions, that may be overwhelming for those affected. Clinicians can conduct tests to determine whether or not the symptoms are related hyperosmia (see below) or parosmia.
Other terms that may be helpful:
- Idiopathic smell impairmentThis is the medical term used when, after extensive testing, no cause for the smell impairment is found in a patient. You can read more about this in our information sheet here.
- Hyperosmia is the medical term for an increased ability to smell. It is not considered to be a type of smell impairment, and researchers suggest that it is only used after smell testing by a clinician.
Types of taste impairment
People who lose their sense of smell can sometimes think that they have lost their sense of taste, because of the significant contribution that the sense of smell makes to flavour perception. This is more fully explained here.
Taste-specific disorders are less common, but no less impactful.
- Ageusia is the medical term for the inability to taste. True taste loss – where a person’s ability to taste food is compromised whilst their sense of smell is unaffected – is rare. When a person is diagnosed with ageusia, this means that their ability to detect the basic tastes (sweet, sour, bitter, salt and umami) is lost, but their sense of smell is unaffected.
- Hypogeusia is the medical term for a reduced ability to taste.
- Dysgeusia is the medical term for experiencing distortions of the sense of taste. It may also be referred to as parageusia.
- Phantogeusia is the medical term for experiencing a lingering, often unpleasant taste even though there is nothing in your mouth. These phantom tastes are often unpleasant and can persist for a time.
- Idiopathic taste impairment. This is the medical term used when, after extensive testing, no cause for a taste impairment is found in a patient. You can read more about this in our information sheet here.
You can read more about taste impairment in our information sheet here.
Reference
Olfactory nomenclature: An orchestrated effort to clarify terms and definitions of dysosmia, anosmia, hyposmia, normosmia, hyperosmia, olfactory intolerance, parosmia, and phantosmia/olfactory hallucination. Hernandez, A. K., Landis, B. N., Altundag, A., Fjaeldstad, A. W., Gane, S., Holbrook, E. H., Huart, C., Konstantinidis, I., Lechner, M., Macchi, A., Portillo Mazal, P., Miwa, T., Philpott, C. M., Pinto, J. M., Poletti, S. C., Vodicka, J., Welge-Luessen, A., Whitcroft, K. L., & Hummel, T. (2023). Journal for Oto-Rhino-Laryngology, Head and Neck Surgery, 85(6), 312–320. https://doi.org/10.1159/000530211