Loss of Sense of Smell (Hyposmia)

Reviewed by: HU Medical Review Board | Last updated: November 2022

One of the non-motor symptoms of Parkinson's disease (PD) is the loss of sense of smell (hyposmia). Most people with PD experience a reduced sense of smell at some point. Reduced smell may be an early sign of PD. If you lose your sense of smell, you might also lose your ability to taste food properly. This is because the senses of smell and taste are closely linked.1

What is hyposmia?

A loss of smell, also known as hyposmia, is a condition in which you have a reduced ability to smell. This can happen suddenly or gradually over time.1,2

Why does PD cause a loss of smell?

The cause of hyposmia in PD is unknown, but is likely due to the disease process itself. Some research has shown that in people with PD, the area of the brain that processes smell might be smaller.1,2

Other causes of hyposmia

Parkinson's disease is not the only condition that can cause a reduced sense of smell. Other causes of hyposmia can include:1-3

  • Nasal congestion, cold, allergies, or viral infection
  • Head injury
  • Aging
  • Nasal polyps, which are noncancerous growths inside the nose or sinuses

What are the symptoms?

The symptoms of hyposmia can vary depending on what is causing it. However, common symptoms include:1,2

  • Having a hard time identifying smells
  • Not being able to smell as well as you used to
  • A reduced sense of taste
  • Nasal congestion and swelling

Diagnosis

If you are having trouble smelling, see your doctor. An ear, nose, and throat specialist (ENT) can help. They will ask about your symptoms and do some tests to see how well you can smell. These tests may include having you:2

  • Smell a piece of paper with a strong scent on it
  • Taste different foods and drinks
  • Sniff different odors

You may need additional tests to rule out other causes of your symptoms.2

Treatment

There is no cure for hyposmia, but treatment may help improve sense of smell in some people. Treatment options vary depending on the cause of your hyposmia and include:2

  • Nasal sprays or drops to clear congestion
  • Medicine to treat allergies or a cold
  • Surgery to remove nasal polyps
  • Smell retraining therapy to improve smell function

What can you do?

If you notice that you are no longer able to smell as well as you used to, it is essential to see your doctor. There is no specific treatment for hyposmia. But there are several actions you can take to help improve your ability to smell, including:4

  • Keeping a diary to help identify any specific foods or drinks that may be causing the problem
  • Avoid strong-smelling drinks and foods, such as garlic and onions
  • Using scented products sparingly
  • Avoiding smoke and pollution

Knowing what to look for if your sense of smell seems decreased can help you get the support you need. If you have Parkinson's disease and are experiencing a loss of smell, it is important to talk to your doctor about the best way to manage your condition. There may be drugs or other treatments that can help improve your quality of life.

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