Hyposmia: Symptoms, Causes, Related Conditions, Diagnosis, Treatment and Prevention

It is a medical term that describes at least a partial loss of the sense of smell.


This condition can be annoying and dangerous when it occurs. Estimates suggest that 2 million people or 12 percent of adults in the United States have this syndrome and other disorders that affect their ability to taste and smell.

When people think about the taste or flavor of food, they are considering a combination of sensations, with only a few coming from the tongue and palate.

The sense of smell contributes greatly to the taste of food, as many people will have noticed after a cold when food seems to lose its flavor.

This is the reason why some people with hyposmia think they are suffering from a taste problem when only their sense of smell is affected.

Causes of hyposmia

Hyposmia is a symptom of several medical conditions and may be temporary or permanent.

The loss of smell can occur due to problems in the nose, brain or nervous system. In certain cases, it is a sign of a more serious underlying problem.

People may lose some of their ability to smell for several reasons. Possible causes of hyposmia include:

  • Allergies
  • Wounds to the head
  • Infections, like the flu.
  • Small growths in the nose or sinuses, known as polyps .
  • Deviated nasal septum.
  • Influenza.
  • Hay fever.

Chronic sinus problems, including chronic sinusitis , have also been linked to reductions in the sense of smell.

When the sinuses remain blocked, swollen and full of mucus for more than 12 weeks despite treatment, the ongoing inflammation can damage the cells that allow people to smell.

At least 250 different medications also affect the sense of taste and smell, and some of these medications can cause hyposmia. They include:

Additional contributors to hyposmia include long-term exposure to certain chemicals, smoking or the use of recreational drugs, such as cocaine.

Age is another major factor in the partial loss of the sense of smell. According to the American Academy of Otolaryngology, the sense of smell is optimal when people are between 30 and 60 years of age.

It begins to weaken after that. Therefore, a degree of hyposmia is common in older adults, affecting 39% of those over 80 years of age.

Other conditions that can cause a deterioration of smell include:

  • Dementia (memory loss), like Alzheimer’s.
  • Neurological disorders such as Parkinson’s disease or Huntington’s disease.
  • Tumors in the brain.
  • Malnutrition.
  • Nasal tumors or surgeries.
  • Wounds to the head
  • Sinusitis (sinus infection)
  • Radiation therapy
  • Upper respiratory infections.
  • Hormonal disturbances
  • Nasal decongestant use
  • Certain prescription medications, such as antibiotics and medications for high blood pressure , can also alter your sense of taste or smell.

Related conditions

Hyposmia can also be a sign of other health problems, including:

  • Parkinson’s disease
  • Multiple sclerosis (MS).
  • Alzheimer disease.
  • Obesity .
  • Diabetes type 1.
  • High blood pressure
  • Malnutrition.

Most people who have hyposmia will not develop Parkinson’s disease. However, most people with Parkinson’s disease, which is a condition of the central nervous system, lose some of their ability to smell.

Due to the relationship between hyposmia and Parkinson’s disease, a test to reduce the sense of smell could lead to an earlier diagnosis of the disease.

In the case of one of the most common forms of dementia in the United States, the possibility of using a smell test to detect early diagnosis is also under investigation.

Multiple sclerosis (MS) is another condition that has been associated with hyposmia. A study of people with MS found that 40 percent of their participants had at least a partial loss of their sense of smell.

The greater their disabilities related to MS, the more difficult they were to identify a specific aroma.

Multiple studies have found that people with type 1 diabetes may have trouble detecting and distinguishing odors. The more discomfort they had due to the damage to diabetic nerves, called peripheral neuropathy, the more problems they had with their sense of smell.

Although head and neck cancers may not directly affect the sense of smell, radiation treatment for these conditions may cause some degree of hyposmia.

How could hyposmia progress?

Hyposmia often improves without treatment, particularly if it is caused by seasonal allergies or an infection of the respiratory tract. A person who senses a reduced sense of smell when they have a cold, usually finds that they return to normal a few days or weeks after they recover.

When hyposmia is caused by a head injury or a significant inflammatory lesion in the cells involved in olfaction, a full recovery may not be possible, even with surgery.

However, some medications and the retraining of the sense of smell have been shown to be useful for people with hyposmia.


If you have a deteriorated sense of smell, call your doctor before using over-the-counter (OTC) treatment products. Let them know when you first noticed changes in your ability to smell and other symptoms you may experience.

Answering the following questions can help the doctor identify what may be causing your impaired sense of smell:

  • Can you smell some foods but not others?
  • Can you feel the taste of the food?
  • Do you take any medications?
  • What other symptoms do you have?
  • Have you recently had a cold or flu?
  • Do you have or have you had allergies recently?

After reviewing your medical history, the doctor will perform a physical examination of your nose to see if there are blockages in your nostrils. These tests may include:

  • CT scan.
  • MRI scan.
  • Bone scan.
  • Nasal endoscopy (examination of the nasal passages with a thin tube containing a camera).

These tests will help the doctor closely observe the structures inside your nose. Imaging tests will reveal if there is a polyp or other abnormal growth that obstructs the nasal passages.

They can also help determine if an abnormal growth or tumor in the brain is altering your sense of smell.

In some cases, your doctor may need to take a sample of cells from your nose to make a diagnosis.


The deteriorated smell caused by a viral or bacterial infection is usually of short duration. If you have a bacterial infection, antibiotics may be given to speed up the healing process. This will help restore the smell.

Decongestants and OTC antihistamines can help relieve nasal congestion caused by allergies.

If your nose is blocked and you can not blow your nose, use a humidifier to moisten the air. Keeping a humidifier in your home can loosen mucus and help relieve congestion.

If a neurological disease, a tumor or other disorder causes your deterioration of smell, you will receive treatment for the underlying condition. Some cases of bad smell can be permanent.

How to prevent the deterioration of smell?

There is no sure way to prevent the loss of smell. You can minimize the risk of catching colds or bacterial infections by following these steps:

  • Wash your hands frequently during the day.
  • Wash your hands after touching public areas.
  • When possible, avoid people who have colds or flu.
  • Familiarize yourself with the possible side effects of all your prescription medications.