The aroma of just-baked cookies, roses in full bloom, and other everyday scents make our lives richer in ways we often taken for granted. Yet, when the sense of smell is lost or compromised—a condition called anosmia—it is not just enjoyment of life that is affected but also health and safety. Our sense of smell helps whet the appetite and also serves as a warning system to avert dangers and toxins.

“Two of the great joys in people’s lives are the sensations of smell and taste,” says R. Peter Manes, MD, an ear, nose, and throat specialist at Yale Medicine. “When these senses are altered or absent, people lose that pleasure and can feel isolated from those around them who are not afflicted.”

Anosmia is the partial or full loss of smell. Anosmia  can be a temporary or permanent condition. You can partially or completely lose your sense of smell when the mucus membranes in your nose are irritated or obstructed such as when you have a severe cold or a sinus infection, for example. 

But if the inability to smell isn’t related to a cold or sinus infection, or it doesn’t return after congestion clears, you should see a doctor. It could be a symptom of another issue.

The sense of smell is important to overall health and nutrition since diminished sensations can lead to poor appetite and malnutrition, especially in the elderly. An altered sense of smell may pose other health-related problems. People with anosmia may accidentally consume soured or rancid foods because they are unable to detect odors that signal spoilage. Those with anosmia may also be unaware when they are breathing toxic, polluted or smoke-filled air. 

Although rare, some people are born without the sense of smell, which is a condition called congenital anosmia. This occurs when there is either an inherited genetic disorder or abnormal development of the olfactory system (the body’s sensory system for smell) occurring before birth. Unfortunately, there is no cure for congenital anosmia.

Most commonly, anosmia is caused by:

• The common cold
• Influenza (flu)
• Sinus infections (acute sinusitis)
• Hay fever
• Non-allergic rhinitis (congestion and sneezing not caused by allergies)
• COVID-19

There are other causes of anosmia, too. When the nasal passageways are obstructed in some way, the ability to smell can be affected. Examples include:

• Tumors
• Nasal polyps
• Nasal deformity

In addition, the olfactory pathways, which send messages between the nasal passages and the brain, can become impaired from age and from certain medications. Also, certain medical conditions can dull or diminish the sense of smell. These include:

• Alzheimer’s disease
• Brain aneurysm
• Brain surgery
• Cancer
• Chemical exposures to insecticides or solvents
• Diabetes
• Huntington’s disease
• Kallmann’s syndrome
• Klinefelter's syndrome
• Korsakoff’s psychosis
• Malnutrition
• Multiple sclerosis
• Multiple system atrophy (MSA)
• Paget’s disease
• Parkinson’s disease
• Pick’s disease
• Radiation therapy
• Rhinoplasty
• Schizophrenia
• Sjorgren’s syndrome
• Traumatic brain injury
• Zinc deficiency

Your physician will examine you to determine the cause of your smell disturbance. Because anosmia can result from any number of  conditions, your doctor will first address the primary condition that seems to be causing the problem. 

For example, if you have allergic sinusitis, treating it can help restore the olfactory sense. If nasal tumors, nasal polyps or nasal deformities require surgery, that may be the first step. In other cases, anosmia can be an early symptom of a disease such as Alzheimer’s or Parkinson’s.

However, it’s important to know that sometimes the cause of smell disorder can’t be determined for certain. And sometimes anosmia cannot be treated.

At Yale Medicine, we take the time to identify the cause of your smell disturbances and identify appropriate treatment. “While changes in smell are quite common,” Dr. Manes says, “they can be the first sign of something more serious. At Yale Medicine, we are able to appropriately and accurately investigate the actual cause.”